Component parts and Assembly
Fuel Flap lock, Fuel Filter, Fuel lines, Petrol Tank, Petrol Pump/Fuel Level Sensor.

Danger of Explosion and Fire
Before considering working on fuel lines, replacing fuel filters, removing petrol tanks and alike, be aware of the Extreme Risk of FIRE and EXPLOSION

Shell Oil Comments - A MUST READ!


Here are some reasons why we don't allow cell phones in operating areas, propylene oxide handling and storage area, propane, gas and diesel refueling areas.
The Shell Oil Company recently issued a warning after three incidents in which mobile phones (cell phones) ignited fumes during fueling operations In the first case, the phone was placed on the car's trunk lid during fueling; it rang and the ensuing fire destroyed the car and the gasoline pump.

In the second, an individual suffered severe burns to their face when fumes ignited as they answered a call while refueling their car!

And in the third, an individual suffered burns to the thigh and groin as fumes ignited when the phone, which was in their pocket, rang while they were fueling their car.
You should know that:-
Mobile Phones can ignite fuel or fumes
Mobile phones that light up when switched on or when they ring release enough energy to provide a spark for ignition
Mobile phones should not be used in filling stations, or when fueling lawn mowers, boat, etc.

Mobile phones should not be used, or should be turned off, around other materials that generate flammable or explosive fumes or dust, (I.e., solvents, chemicals, gases, grain dust, etc...)

TO sum it up, here are the Four Rules for Safe Refueling:-
1) Turn off engine
2) Don't smoke
3) Don't use your cell phone - leave it inside the vehicle or turn it off
4) Don't re-enter your vehicle during fueling.
Bob Renkes of Petroleum Equipment Institute is working on a campaign to try and make people aware of fires as a result of 'static electricity' at gas pumps. His company has researched 150 cases of these fires.

His results were very surprising:-
1) Out of 150 cases, almost all of them were women.
2) Almost all cases involved the person getting back in their vehicle while the nozzle was still pumping gas. When finished, they went back to pull the nozzle out and the fire started, as a result of static.
3) Most had on rubber-soled shoes.
4) Most men never get back in their vehicle until completely finished. This is why they are seldom involved in these types of fires.
5) Don't ever use cell phones when pumping gas
6) It is the vapors that come out of the gas that cause the fire, when connected with static charges.
7) There were 29 fires where the vehicle was re-entered and the nozzle was touched during refueling from a variety of makes and models. Some resulted in extensive damage to the vehicle, to the station, and to the customer.

8) Seventeen fires occurred before, during or immediately after the gas cap was removed and before fueling began.

Mr. Renkes stresses to NEVER get back into your vehicle while filling it with gas.
If you absolutely HAVE to get in your vehicle while the gas is pumping, make sure you get out, close the door TOUCHING THE METAL, before you ever pull the nozzle out. This way the static from your body will be discharged before you ever remove the nozzle.
As I mentioned earlier, The Petroleum Equipment Institute, along with several other companies now, are really trying to make the public aware of this danger.
I ask you to please send this information to ALL your family and friends, especially those who have kids in the car with them while pumping gas. If this were to happen to them, they may not be able to get the children out in time.

Wise Words, as a retired Fire officer I would simply add that it does not have to be the petrol fumes from your car that the spark from your phone ignites, it could easily be the fumes from an adjacent fuel tank. The ignition of the fumes will also be accompanied by large flash of flame which could easily prevent you getting back to your own car to rescue children who should be trapped into child seats of cots , So please abide by the strict rules outlined above.

, Working on your Car
All sources of ignition should be extinguished/eliminated before starting work. Remember to release pressure build up in the fuel tank by removing the cap, the cap can be replaced once the pressure in the tank has equalised with atmospheric pressure.
In addition ensure that all precautions are taken to ensure that the flammable explosive vapours are not ignited by breaking inspection lamp bulbs or similar ignition sources, including the above, CELL/MOBILE PHONES .

Such equipment should be suitable for the purpose, Bulbs protected by Glass globs or low voltage
If you are a smoker and use lighters including gas always remove them from your clothing/pockets before crawling/laying under and around your vehicle. It is possible for the lighter mechanism to be inadvertently actuated thereby creating an ignition source in the working area.
Where possible carry out any such work in a well ventilated area.
Always wear eye protection.
Petrol & diesel fuels are known to cause skin problems, therefore avoid all possible contact.
Where these requirements cannot be met you would be well advised to leave the job to the professionals.

Useful information is displayed on the inside of the fuel filler flap. Ensure you use the correct t fuel, Oh yes it happens the 100s of thousands of motorists a year the wrong type of fuel put into the vehicles fuel tank.

I make no apologies if this insults some visitors knowledge of their car but when I purchased my Baby-Benz (BB) in August 2003 and found getting information very difficult in deed. MB dealerships didn't want to know because I hadn't bought the car from them, the dealer I did buy it from appeared to know little about the car from a technical point of view. come to that neither did the sales team in Mercedes Showrooms .
Of course that situation was eased when I found the Baby -Benz owners club then I realised a number of other owners were in the same boat as myself, so decided to try and do something about it.
So here it is, 'Lofty's Homepage' and if it saves just one visitor some grief and helps them understand their car better and saves them money , then I will have achieved my aim.

Fuel flap locking devise The third photo, the devise mentioned in the owners manual If for any reason the lock doesn't allow you to open the flap then:- Open the flap marked for the first aid kit, O/S there you will find the hatch that allows access to the rear light cluster. Remove the oval felt pad & place your hand with caution due to sharp edges into the access between the body panel and the boot lining, moving your hand towards the filler flap or following the yellow pipe, incidentally the connection onto this unit is the same as on the headlight remote adjusters. The devise photographed is at the far end of that pipe, do not pull on the pipe, it is not the release mechanism. To release the flap pull the PIN towards you. Job done

Where the vacuum system is gas tight you may have problems pulling this pin towards you . If this is the case and you need to access the fuel cap then carefully remove the yellow pipe and connector from the vacuum solenoid valve this will allow the diaphragm in the unit to move easily and the pin can be withdrawn, the fuel flap can now be opened.

This comment comes from one of my readers:-
One instance of instance of stupidity on my part was trying to release the pin for the fuel flap, after 10 or so minutes of tugging at it with no success I thought I'd just press the flap at the same time - hey presto - my mistake was that I was expecting the pin to move about 10mm or so and not just a smidgeon.(Small amount)
Thanks kevin.

Remember to replace the yellow pipe /connector when the vacuum pump is repaired or replaced.
This photo was taken with the rear lamp removed.

When Bob in Australia has problems he found that the two parts of the component had come apart, in his case they were a push fit, on the component inside the car body work his unit has a catch which released it from the component part in the fuel filler access point. That does not appear to be the case with mine.

Battery is good Engine turns over but Car Fails to start, after multiple tries eventually starts
A couple of owners, members have had problems with starting, after a great deal of work on one members part he found that the problem was the starter relay which was failing to sent power to the fuel pump.
This fault which can be intermittent will not show up on diagnostics equipment.
If you suffer from the same symptoms then you can easily test to see if it is your relay at fault by switching over two compatible relays, The relay powering the fuel pump is K7
This can be switched with K10 which powers the rear screen heater. This at least will enable you to see if your problem is sticky relay contacts. Both of these relays are located on the main fuse board under the drivers feet. Fuse, Relay Chart
and Main Fuse Board Note that both are Black cased relays, Part no Relay (002-542-13-19) You will only be able to obtain the correct replacement from Mercedes-Benz parts and the cost is approx 10.00 26/10/08.

Petrol Cap

When opening the petrol cap after a run it is perfectly normal to hear a hissing of air when the cap is initially opened. This does not occur when the car has been standing idle for a period of time, both instances are normal and should not therefore be considered faulty.

Point worth noting
Engine diagnosis indicator lamp
If the fuel tank has run dry, (Run out of fuel) the car must be started three to four times after re-fuelling. The emergency operating mode is canceled and the dash warning lamp will go out. The car does not need to be checked.

Smell of Fuel.

One of the most common complaints on the petrol fuelled 'A' Class is a smell of fuel in the cab, and yet there appears to be no leak of fuel.
If this situation occurs on your car then there is a need to check the clips on the fuel line . Mercedes have tended to use the crimped type of clips which are applied using special crimping pliers. These tend to leak after a period of time and therefore need to be replaced with 'Jubilee' type, screw adjustable clips, which are available from Mercedes-Benz Parts Departments.
To replace these you will need to remove the Air Filter housing as space is tight. A shows the hose going onto the metal fuel pipe which travels the length of the car and terminates at the fuel filter.

This mail was received from Jan in France which highlights that the problem is still on going.18.12.10
Today I replaced the little rubber fuel line (kind of U-shaped) behind the engine which is fixed to the metal fuel conduit. I kind of guessed how to proceed but I was hesitating how to dismount the air filter being afraid to break things in getting proper access but found everything I needed on your site. You might add that it is easier to refit the air filter by putting a bit of dishwasher detergent on the three plastic pins or in the rubber rings, that makes life a lot easier to put things back together. And maybe make a recommendation on how to re-clamp the original factory tube clamps (use new screw type ones? because the original ones are a pain to pinch close unless one has the special tool for it, if it exists)

This tube is by the way a serious safety hazard. The original part has some plastic sleeving over the rubber tubing but that doesn't protect it from wearing through since it is touching the edge of the air filter casing. VERY clumsy on the part of Mercedes, that should never have occurred from such an excellent car manufacturer. Time and vibration wore a BIG hole in it from which fuel was spilling at an enormous rate. The tube sitting just over the alternator I was a few inches from having a engine fire!! The new design is a tubing with two thick rubber rings around it that protect the tube from touching the air filter. My car is from 2001 but with few km's. Maybe worth mentioning on your site. There may be more A160's out there with this potential fire hazard. People HAVE TO replace it with the new part before it wears out!!

I can confirm the special tools are required to fit the Crimped clips, so ensure you use a good quality or MB spare part see below for details .


This photo shows the opposite end of the rubber tube going onto the metal pipe which comes from the fuel tank
However before you replace/remove/or tighten any clips check the condition of the hose, if as is normally the case the car is an early model then you would be well advised to replace the hose as it may well be perished, bear in mind that it is almost certainly the original and will be many years old as well as having been exposed to the temperatures of the engine bay.
It is quite a short length and will be available as a spare part from Mercedes-Benz, also purchase the clips at the same time making sure they fit over the diameter of the new hose, changes to spec of the hose can result in some clips being supplied being too small, equally you must be able to clamp the hose tightly when it is fitted.

B shows the flexible pipe connection onto the fuel induction rail. You will note that a screw adjustable hose clip has already been fitted.

Being screw type clips this will be an easy job , however you will need to remove the air filter and housing again by no means a difficult task and well within the capability of most DIY owners.
The small clips of the screw clamp type these are available from MB. part number, MN 916 002 012100 (020205) clamp (Gemi 12 Mercedes Clips)

Rusty and porous fuel pipes
Dear Lofty
My other half has a 1998 A class 160 Avantgarde. She loves it. She has done over 182,000 miles in it, and she drives so gently, I am confident it will clock up a lot more. She really does not want to replace it as she doesn't like the new-shape ones, but I got the ultimatum that either we fixed the petrol pong, or it would have to go ....
This is not the first time we have had the petrol pong, however it has got progressively worse as time has gone by, and now it is occasionally so bad that the fumes in the car will make your eyes water.
Since I now know what is wrong, it may help to describe the symptoms.
The fundamental symptom is a smell of petrol in the car at various times.
It is important to understand that the smell has progressed, over several months, from an occasional smell in the car, very intermittently, to the last few days, when the smell has been apparent in the car most of the time, and some of the time it was almost overpowering. Lately it would require the windows to be opened, even though the weather has been freezing.
So that is the symptom, where one would observe it, and the extent of it, so let us describe when we got it.
Initially the smell seemed to be apparent only under two very different circumstances.
1 When the tank was half full.
2 When the brakes were applied.
In the last few days the smell was apparent under the bonnet, and eventually, even outside the car. Subjectively, we always felt that there was always less of a smell on the passenger side of the car than on the drivers side. That is the "when" of things.
The road to our fix...
Initially the Mercedes garage seemed to fix it, temporarily, with a change of some pipes and the carbon can. But we were never really convinced it had gone entirely.
It may well be that we have had two different problems, one that your existing help will fix, and then a further problem.
With a recurrence of the smell, though, I started out replacing pipes, as suggested by your site, but this time it did not effect any change.
Today I have changed the carbon can. As I finished that, I wanted to check I had got everything working, so I got the engine running and got under the car with the under-tray removed, to make sure that all was well. (No safety issues with that as I have a Hamer car lift, and they are a fantastically useful tool).
All was indeed well with the can, so engine off and underneath again to replace the under-tray. In spite of the fact that all looked well and there was no trace of any petrol anywhere under the car, the smell under there was still very strong. I got a safety lamp and had a really good look at the other feed pipes. The main feed, (steel) and a plastic return pipe are briefly visible as they emerge from a steel-faced plastic shroud on the under-tray, and they pass toward the front of the car, and after a horizontal bend, under the car, they bend upwards, following the line of the firewall/bulkhead, where they emerge in the very place that you have such useful pictures of on your original documentation. As these pipes bend round towards the vertical there is a layer of black felt insulation on the underside of the car. As the main feed pipe bent, on the underside of the car, I noticed that a small area of paint had fallen off, and that the bend looked as if the pipe was rusty. It also looked wet. I initially thought that this was because of the replacement of the flexible feed pipe to the injector rail, which is at the top of this pipe, but I wiped it, and there was my leak.

The leak is actually in the steel pipe, but it is rendered very difficult to find because the petrol was soaking into the felt insulation, and being wicked away. This area is about 250 - 300 mm (a foot) away from the catalytic converter, which I guess was why we never saw any residue or staining under the car. It is probably hot enough there to make the petrol evaporate out of the extensive surface area afforded by the felt "wick", and probably accounts for why there was never a drop of petrol visible. The pipe has rusted when the paint didn't stick on the bend, and the rust has made the pipe become porous.

I will now be getting a new pipe from Mercedes, but for this afternoon, I thought I had better get into "Imagine you are on the Dakar Rally" mode, and try to get a temporary fix. Basically, that has consisted of cutting through the steel pipe at the point where it was leaking, retrieving the old, but perfectly serviceable flexible fuel feed pipe I had just replaced, and cutting a length of it to slide over both ends of the now severed pipe. Jubilee clips tighten the pipe on, and no more leak. Having done this, I would say two things. Firstly it is a safe fix, but it must be temporary. Secondly, it is not one to be considered if you are faint of heart. You will need to cut the steel pipe with a hacksaw. There is no room for anything other than the blade, which you will have to hold in your hand, wrapped in cloth, to avoid bloodshed. Cutting the pipe will take about an hour, as you will be getting about 25mm, or three-quarters of an inch of travel, on each stroke of sawing. It all starts OK, but when you get to the bit in the middle of the pipe, my experience is that you can only cut on the back-stroke and it feels like fewer than ten of the saw teeth actually touch the pipe.

So, that is the beginning of the end of my petrol-pong saga. I have no idea yet how difficult replacing the whole pipe will be, but I have a bit of a premonition that evolution might turn out to be another saga of it is own.
Thanks for the help your site has given me, and I hope you find this useful.
Best regards
David did contact me again and yes, having purchased a new petrol pipe which took some time to get, he then found that it was impossible to replace it without removing the power train as the metal pipe is located between the upper engine and the underside of the floor making it impossible to remove he therefore re-checked his previous repair and left well alone.
He does make the point that even have undertaken the previous repair, eliminating any leaks , the smell of petrol took some weeks to completely disappear, this due to the fuel having soaked the absorbent material in the near vicinity of the leak.
So If your new clips do not cure the problem you may need to look further but bear in mind the mileage of the above car which obviously has a bearing on the condition of not only fuel lines but metal brake hoses as well.

To get at and remove the old crimped clips you will almost certainly have to remove the Air filter housing, an easy job if you just take your time.

The throttle Body controls the amount of fuel mixture demanded by the engine relative to the accelerator pedal movement. this need to working correctly and be free of contamination, the butterfly as seen in the photo which is sprung loaded should be free of contamination and shut fully when the engine is at rest, if signs are seen that this is dirty then as with the MAFS cleaning procedure set out on the SVC site this should be cleaned using carburetor cleaner take great care not to damage the components within or a new unit will be required.

This is a photo taken of the components inside the front casing of the throttle body taken by Victor, a fellow owner who had problems with the sluggish movement of the flap integral of the throttle body which was cured to a large degree by spraying carburetor cleaner into the throat of the body, this in effect cleaned the mechanism on which flow control flap operates
However if you intending removing this cover take great care to ensure you do not break the plastic retention clips that hold the cover in place.
1 Shows the electronics, motor and drive.
2 Appears to be a magnetic head, all part of this sophisticated mechanism designed along with the electronics of the ECU, and Mass air flow sensor to replace the old carburetor system.
These units are expensive to replace, so if you are intending to inspect or carry out work on it, take care not to damage beyond repair.
The Throttle body is controlled by the accelerator pedal which is also fitted with a electronic sender/sensor unit.

For details of removing the Air filter housing see page 16. Go to page.16.

Fuel Filter
The Main fuel filter is situated forward and central to the fuel tank, roughly in line with the 'B' Posts.
The fuel filter should be changed at 45000 miles or 4 years which every is the sooner,
To access the filter the under floor pans will need to be dropped,
One of the symptoms of a blocked or semi blocked filter will be a loss of power and engine stuttering and stalling, however I had not noticed these symptoms on my car, BUT having replaced the filter there is a very distinct difference in the power when pulling away.

And having now done the job I'm also in a better position to detail the procedure. 2/08/08

Please ensure you read the warning at the head of this page before commencing any work on fuel systems. as well as page 5 to ensure safe working
Although this is an easy filter to replace it can be difficult to get the car to a height whereby you can lower the under floor pans sufficiently and still safely do the filter change, this is mainly due to the floor pans being hinged one side in most cases it will be best left to the garage.

Parts Required
(a) 1 fuel filter New filter MA002 477 38 01
(b) 2 (two) jubilee type clips approx 15-18mm in Diameter
(c) 1 (one) small clip MB. part number, MN 916 002 012100 (020205) clamp (Gemi 12 Mercedes Clips) as shown in the photo above.

Tools required
(a) A container will be required to collect the small amounts of fuel that vacate the pipes and filter on removal and in which to place the expired filter.
(b) Small socket for removing the under floor pan fixing screws/bolts ( )
(c) T20 Torx bit, to remove the canister fixing from the chassis
(e) (d) Cutters for removing old crimped clips from hoses
(e) Screw driver for tightening clips
(f) Large flat bladed screw driver for easing rubber connecting pipe from old filter Spigots
(g) Cloth


(a) Having driven the car onto the my modified ramps and chocked the front wheels, hand brake ON, I raised the rear of the car by placing wooden blocks under the rear wheels until I had gained sufficient height to work under the car ( Standard House bricks and some building blocks are not suitable for this purpose.)

(b) Ensuring the car is secure and stable, (See page 5,) lower the under floor panels. The N/S of each panel is hinged and can only be lowered to the vertical position if a suitable pit of or vehicle lift is available ( I released all panels as I also wanted to spray the under body with duck oil )

The fuel filter is easy to locate once having lowered the panels see A
There are 4 pipes attached to the filter.
1 Feed to engine , marked Mot (clipped)
2 Feed from pump marked ,Pump (clipped)
3 Pipe from tank , marked Tank (clipped )
4 Return to carbon canister, Marked, Can (push fit)

Take care when removing pipes 2 & 3 as it is easy to re-fit these incorrectly

The Charcoal canister complete with fuel filter can be lowered by removing the single fixing Torx T20 screw AND see below

Then sliding the whole assembly towards the outside of the car, keeping it level, the assembly will then be released from the chassis fixing points. I found it easier to remove the old crimped clips at this point however do not apply undue pressure on the pipes going away from the filter.
You will note that I have not used clamps on the pipe work as in the original page, I have deleted this because ,
1 the pipe work is plastic and I did not want to split it , and 2 there is very little fuel runs from both the filter and pipes when removed . However it is strongly recommended that this be caught in a suitable container and removed from the work area to reduce the fumes around the working area.

The carbon canister can now be lowered complete with the fuel filter,
The fuel filter can now be slid from the holder.
Fit new filter ensuring the directional arrow points away from you and that the tube connection spigots are positioned correctly ( See photos)
Replace all components, including fitting New securing clips, (the existing crimped clips used on the fuel lines are not re-usable)Note. Remove the crimped clips nearest to the filter canister, it is not necessary to replace/disturb the remaining clips unless signs of seepage or leaking is present.
unless you have access to crimping pliers, it is recommended that screw type clips be used as replacements, these are available from Mercedes Parts
Re fit all components in reverse order ensuring the carbon canister locates into the fixing points on the chassis

Shows the filter removed from it is housing , the vent tube 4 which is not secured with a clip has been removed.Checking your Work
I started my car at this point,
Having turned the ignition key the car started after approx 20 seconds
Check for leaks.
Replace the T20 carbon canister securing screw.
Re-secure the under body panels.
Note that these panels are stepped and inter-lock.

In the event of petrol smells at any time , all fuel lines should be checked for leaks.

The Function of the Charcoal canister is to remove petroleum vapours/smells. Note the open vent at the top of the filter end.
Where petrol smells are detected check all clips including those on the fuel tank flexible filler hose

The filter is clearly marked as well as the size of the attached spigots will guide the installer when fitting the pipe work.

The cut away filter is the one removed from my car, at this point in time I'm not wholly sure how it works . Fuel comes from the pump into the filter body and exits at the other end to the motor, however in addition we have a hose going to the tank and another going to the carbon filter. I'm of the opinion that the hose going to the tank is a return pipe or vent for the tank, at the head of the filter where the carbon canister pipe attaches there is a Fuel pressure regulator.
In the lower half of the photo you will see two filters, the black one

A has been removed from my used fuel filter, the other is a new oil filter. There is no doubt in my mind that a new fuel filter starts its life the same colour as the oil filter when new. B

See Diagram below

Thank you John for providing more details

And what will happens if I do not replace the filter?

In this case this photo was kindly sent to me from Jorge in Brazil, his car wouldn't start for obvious reasons, as can be seen the terminal within the fuel pump assembly has burnt out.
I will be asking Jorge about the condition of his fuel filter but in the meantime please be aware that the replacement of the fuel filter at the prescribed period is necessary if you are not going to encounter the same problem. A blocked or partially blocked filter can cause the fuel pump to over heat and burn out which is a difficult and expensive item to replace mainly due to its location and because the tank has to be emptied and lowered .

Fuel lines going to and from the tank attached in a number of instances to plastic spigots, make sure these are not strained or damaged.

Well you could quite easily finish up like Mike a fellow owner, in burning out the motor on the fuel pump. Result New pump required,

Before even considering starting the job make sure you have at least 3 (three) spare MB hose clips of the type mentioned above, should you then find 'crimped' clips on the various hoses they can be replaced with the screw type clips while the tank is lowered.
It is also advisable to replace the tank seal or at least have a spare to hand. Item 9 on the breakdown above, great inconvenience will result if you find you require these spares after removing the tank.
Should you be faced with the problem of replacing the fuel pump it is worth shopping around for the best deal Bart
decided to go for a Pierburg fuel pump (art.7.22810.60.0) and not en original MB fuel pump. The original MB pump was quoted 360€ incl.VAT. I bought mine for 150€ incl. shippment and VAT. 10/6/2012

You are strongly advised not to attempt to remove a petrol tank containing fuel. Because of one owners misfortune we now have some photo's of the fuel pump assembly, but if you change you filter as prescribed hopefully you will never see the pump from your own car or have to pay for the replacement.
Note the plastic spigots on the top of the pump housing , take care to ensure the various hoses are connected correctly and ensure that undue force is not applied to these units when fitting the respective hoses. this is only a plastic moulding!

The pump photographed from this angle gives us a very good idea of what the fuel gauge sender unit looks like and how it operates, The float the black body 1 attached to the sophisticated piece of moulded plastic 2 is controlled by the level of the fluid in the tank, this in turn moves the contacts on 2 on the contacts on the fixed portion of the unit 3 sending the resulting signal to the fuel gauge, the position of the contacts measures the amount of resistance which in turn is transferred to the fuel gauge giving a measurement of fuel left in the tank.

When the float moves to position 4 the fuel gauge on the instrument cluster should be showing full. The two blue wires carrying the signal.

This photo shows the four contacts, live, neutral, and the two blue wires going to the fuel gauge. When this complete assembly is placed in the fuel tank, the barrel is placed in and the top of the unit complete with contacts pressed down under spring tension, the spring can be seen on the vertical guide.
If the black seal at the head of the unit is at all worn or perished it must be replaced, this one looks to be in good condition failure to ensure it is seated correctly when fitted will result in fuel spills as the car is driven.

Having decided to tackle the job, you will need to get the vehicle high enough off the ground to lower the under floor pans. Both Rod & mike managed by partially lowering the tank, but it does not make the job more difficult because of the lowered tank fouling the panels.

If undertaking the job it is best done in open air or a very well ventilated building, any lighting used must be safe, remember you are dealing with an empty fuel tank in which there may be a residue of fuel and in any case most certainly flammable vapours the
If possible undertake the work in open air with natural lighting THEREBY ELIMINATING ANY POSSIBLE IGNITION SOURCE FROM such items as LEAD LAMPS ETC.

If you are dealing with the filter change a well timed replacement will ensure that the minimum of fuel needs to be drained from the tank. In the case of a defective pump this is not possible as the car will not run.

When draining any remaining fuel do so in a safe manner DO NOT USE ANY FORM OF MAINS ELECTRICAL APPLIANCE TO PUMP THE FUEL,UNLESS PURPOSE MADE FOR THE JOB i.e. INTRINSICALLY SAFE.(an appliance where any spark created is so weak as to not ignite flammable vapours and certified to that effect.)such appliances must be earthed before use.

If DIY then preferably siphon the fuel from the tank into suitable marked container's,
A tube of at least 2.5 metres in length will be required if siphoning the fuel.

Remember also you will need to get this fuel back into the tank when the repair is complete, therefore several small containers are preferable to one large one.
The empty tank will not be heavy BUT it is bulky, take care not to damage the under-floor panels, make provision for supporting the tank.
This photograph of the fuel tank shows the Blue cone shaped unit, I'm quite sure is a one way valve If removing them for any reason ensure you replace them the same as found, there is another on fitted between the filter and the engine located on the under body o/side.
Also shown are two of the four A fuel tank support bolts BUT remember before undoing these there are

It should be noted that the two pumps shown are different in design, including the sender unit attached to the pump casing, so if you do have to purchase a replacement unit be prepared for them to look different in design although always quote your VIN number to ensure you get the correct unit for you vehicle. I am unsure if the sender unit alone can be changed on the later pump.

Having lowered the tank sufficiently the sender unit and pump can be removed this is achieved by removing the 6 (six) nuts from around the Pump/sender situated in the top of the tank. Note that the front 3 nuts are protected by an ant-scuff protector , this can be eased off the nuts . Remember to replace when refitting.

Small hose clamps as shown above and used when changing the fuel filter will also be required to clamp off the hoses going to & from the fuel tank.

It should be noted that the flange B is fixed to the fuel tank NO attempt should be made to remove it The seal S shown in the diagram seats onto this flange. Ensure also that you do not cross thread or damage the six studs attached to this flange or the tank will need to be replaced. It is vital that a seal be obtained between the pump flange and the tank.

Please note the battery lamp head mounted lamp used by Rod, bottom right. This unit, turned ON before starting the job would be satisfactory and would be safer than a mains operated lamp.
Having removed the nuts the unit can be lifted from the tank.
Whether you are replacing the pump or carrying out a possible repair you will still need carry out these tasks.

In Rod's case he removed the sender unit , cleaned the terminals, tested the unit with a meter and replaced it, in Mikes case he had to replace the pump.
Having been removed, the sender unit which connects to terminals A can be removed and tested using a meter by moving the float throughout it is normal operating range. The resistance shown on an Ohm meter was 0 (zero) when in the full position and 200 Ohms when in the empty position. (i.e. when the tank is empty the float is at the bottom of the fuel tank)

Whether you have had the tank down or not one area that can cause petrol smells in seepage on the hose connection from filler to tank, it worth ensuring these are secure and not leaking , C on my car on this flexi filler connection are of the jubilee type and so can be tightened with a small socket.
Goes to the filler,
is the fuel tank.

You will note when working on your car that there are a number of in-line none return valves , on my car New of this are fitted with clips .

This article was in the Sun news paper on the 12th of May 2008

DRIVERS facing bills of up to 5,000 after putting the wrong fuel in their cars are being ripped off, experts insisted yesterday.

Grasping dealers are needlessly replacing entire fuel systems in diesel cars, according to motoring organisations.
They say that simply flushing out rogue unleaded petrol is sufficient.
The alleged scam was exposed by Auto Express magazine — as a boom in the number of diesels on the road leads to more bungles at the pumps.
Researchers were quoted more than 1,000 for repairs to a miss-fuelled BMW 320d, 2,500 for a Ford Focus — and a whopping 5,000 for a Chrysler Grand Voyager.

But Skoda charged just 110 to fix an Octavia, while Audi’s bill was 246.
Editor David Johns said: "Modern vehicles are much more resilient than many garages we spoke to would have us believe.
"This long list of inflated quotes smacks of profiteering."
The AA insisted in many cases "a simple flush-out should solve the problem."
RAC man Elvin Ravenscroft backed up the claim, saying: "People are still driving cars that had fuel contamination a couple of years ago."
Around 120,000 drivers accidentally put unleaded in their diesels every year — about 13 an hour.
Chrysler said it charged for a new fuel system and replacing the tank.
A spokesman said: "This is necessary to remove any contaminants and avoid future issues."
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Thank you to both Rod & Mike for the input on the page.

Very interesting to see that Chrysler and I suspect Mercedes-Benz cash in on this error on the part of owners and drivers. At least we know who our friends are when we are in real trouble, mind you put the right fuel in your car , lofty

Owner has major problems with incorrect reading of fuel gauge
Hi, Lofty
Great site (just purchased CD).
I wonder if you or any of your site visitors can shed any light or offer any tips on this issue.
I have just bought an A140 year 2000 and it has a problem with the fuel gauge reading high.

My first thought was that the sender was the cause so I purchased a new one from Merc A168 542 09 17, removed the tank and pump but the sender was for a new pump design by VDO (I think) and mine is a Pierburg. The pierburg pump I see for sale on e bay, but not the sender on it’s own. Merc do not support the old pump any more so I would have to buy a new pump and sender complete.

New sender looked like this (mine was like the photo below and there was a different method of attachment to the pump)
This is fitted to my car, float rises in anti clockwise direction. Sender slides down onto pump when replacing.

I returned the sender to Merc but I did a dry test first by plugging it in and checking the reading on the fuel gauge. To my surprise the reading was identical to the Pierburg sender, i.e. when the sender float is in tank full position the gauge reads full and when in empty position the gauge reads HALF FULL? To me it seemed clear that the sender was not at fault so I refitted everything including a new fuel filter as suggested! Unfortunately I did not carry out a resistance test on either sender.

I then looked at the cluster which has at some point been changed as it has breakers white pen on. Whilst in Merc I photographed the Part numbers for the correct cluster for my VIN off the computer screen. The part number on the clocks in the car (A168 540 2947) did not match so I figured maybe the clocks fitted were calibrated for a different size tank?
I bought a new cluster A1685400447 from Euromerc ( for 76 including delivery instead of 350 from Merc. I then had Merc Leicester fit and program for 80.00 (1st quote was 150 Merc Birmingham)

The car has just run out of fuel at slightly above full. After 11 pounds of fuel the reading is full and at about 25 pounds of fuel it’s full?
Any thoughts on this one?

In summary both the “incorrect fitment but new” and the “existing” senders give the same incorrect gauge readings
New cluster fitted with part number matching my VIN
If a new sender measures 0 ohms at full then I can’t see how I could have a poor connection problem in the wiring as the problem would be the reverse as I would not be able to obtain a full tank reading with a poor connection?
I have read on internet forums that on other Mercedes you can disconnect the pump connector and turn on the ignition to somehow reset the system but no one I have spoken to at Mercedes has any suggestions about this on the A-Class.
Any advice would be greatly appreciated.

Hi James thanks for your order for the CD I will put it in the post am tomorrow hopefully your get it Tuesday .

My reply
Wow you have has some work and cost trying to sort that out, My immediate reaction was that the wrong instrument cluster has been fitted, that does certainly cause a problem and as you have discovered all parts must match your Vin or you will have problems.

That also applies to the pump and sender unit, What I do not understand is why these have not matched up at some point while you have been chop changing.
As far as I'm aware all the A class w168 models have the same size tanks so I do not think the problem lies there but I know this problem has reared it is head before and do not recall seeing what the answer was . I do know the instrument clusters are not interchangeable

I am surprised that MB were not able to sort this out using 'star' Diagnostics if it is adjustable then it is on the equipment that the re adjusting would be done, did you raise that with them?
If you have now got the correct pump with sender unit and the correct inst/cluster then there is not other option as I see, other than getting them to do a diagnostics test to see if the circuit is showing a fault.

The cheapest way over that is to buy a had held diagnostics tool see my page from a company who will allow a discount, although the model shown I understand is not now available then do your own test and see if it comes up with a fault code.
The only other thing that comes to mind is if the previous owner tampered with the wiring to try and cure the fault of which he obviously would have been aware, a diagnostics test would hopefully show that in the form of a fault code.

Diagnostics tools are fine but located the meaning of the code is something again there are sites on the web that will give you the meaning of the code once you have the readings.
I sorry I can't be of more help on this one, you I think have done everything and more that I would have suggested the Instrument cluster being the first stop.

Owners feed back
Hi, CD received thanks.
Also I have good news in that the fuel gauge is now fixed.
I asked MB to check that they had not simply copied the error / incorrect settings onto the new cluster and indeed they had.
They have now corrected this for free – I think it’s a tank size option or something like that.
This means the cluster I removed would more than likely be ok if it was programmed correctly in the first place, but I bought the car with this problem so could not have known.

It is useful to know that anyone encountering this can sort it easily as long as MB listen to what you are saying they wanted to charge a lot more money to check the whole system before they checked their own programming. As I had already checked the sender it seemed pretty likely to be the problem.
Anyone who’s gauge says full and the car runs out.
fill 10 litres from empty and the gauge says your 3/4 full., and 20 litres from empty and the gauge shows full, has a problem but as can be seen it can be corrected if Mercedes Use their diagnostics tools to re calibrate the readings shown in the fuel gauge which forms part of the instrument cluster.
James that's great news very pleased indeed to hear you have at last got a result. Good luck with the car.
Best wishes 'lofty

So if you have instrument cluster problems followed by a fuel gauge not reading correctly get Mercedes to re-calibrate the instrument cluster, this can only be done by Mercedes Bens or Mercedes-Benz independent garages with 'STAR' Diagnostics equipment. do not be put off like James do not need the complete system serviced or even checked, so do not get stung by MB service departments trying to charge more than is necessary.

EGR Change Over Valve MB part number :-002-540-14-97.
Stuart contacted me as to the location of the EGR valve on his W169 'A' Class as Mercedes had discovered and indicated that his was defective and needed replacing.
I soon spotted this on my own car and sent him the information.
The defect showed itself in that the car has a high pitch squeal when accellorating, as many of us would think this was thought to be a loose poly v Belt slipping but that was not the case, the cause was in fact the EGR valve which was replaced by Stuart once it had been located, very easy to get at and replace.
The Valve is located on the left hand end of the engine just below the Brake fluid reservoir/servo. it is retained by a blade clip onto a plastic bracket. The is also an electrical plug connector on the rear which is released by raising the small clip/tab, the rubber hoses can be eased off of the spigots on the ERG valve body and pushed onto the new unit.
The Change over valves function it to reduce Nitrogen Oxide (NOx)which is one of the gases omitted by combustion engines causing pollution to the atmosphere by recirculating the gases

If a defective valve is not replaced it can cause damage to the engine.

However this is not the end to this story and not what the owner wanted.
He fitted the new valve BUT it did NOT cure the noise.
Once again Mercedes have come up with the answer but it does not cure the problem, at present the cause of the noise is not known.
There have been in my experience and other owners a number of occasions World Wide where Mercedes workshops come up with an answer to a problem and new parts they say are required are fitted at cost to the Owner only to find that the new part does not cure the fault.
In this case the owner is out of pocket by 60-00 but it could have been more, he fitted the part so had not incurred a labour charge.
At this stage I do not know if the fault was diagnosed by diagnostics or pure guess work on the part of the mechanic if the latter is the case then Mercedes in my opinion should be liable for the cost as it did not cure the problem as has been the case on many occasions.

I myself was told that an O2 sensor was defective on my car and having spent out on a new unit from MB found that it did not cure the problem, fault was in fact with the MAFS. I claimed my money back from Mercedes customer service UK and got it

. If you are told that a given part requires replacement on your vehicle, I would first ask on what basis has the assumption been made and only give the go ahead on the proviso that if the new part does not cure the problem the old part will be refitted at no cost to you.
If the fault has been diagnosed using diagnostic equipment then ask for the print out to confirm what you are being told is correct.
Remember you are the one that is paying. And always ask to at least see the old part, which is your property unless you have given authority for it to be disposed of before you see it. It is yours to take away if you wish, unless it is an exchange part.(one where the old part is taken in part exchange against the component fitted)

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