unhcampus

Yesterday the car died getting on the highway, it would idle but not power. There was a check engine light with a low fuel pressure code. There was a strange intermittent buzzing sound coming from the gas tank.

Dealer says its the fuel pump in the tank wanted $1,400 to replace.

Is this an easy job and can anyone here share what they know about how to? Do I need any special tools or clamps?

Thank you!!

Carsy

In the C Class the fuel pump can be accessed through the floor under the rear seat. You should see some electrical wires & a cover with a seal .

unhcampus

Ok, problem solved. I ordered a new fuel pump and sending unit, removed the back seat cushion and replaced both. I used a string to pull the lines that connect the sending unit to the pump so could use the string to pull the new line back through. If you dont do this, be prepare to stick your arm in the tank.

When I replaced the pump, I noticed the fuel level on the pump side was almost empty and the fuel level on the sending unit side was almost full, they were not equalizing. This posed as a problem as once everything was back together, the pump did not have any fuel to prime itself and the car did not start. I solved this by adding 4-gallons of fuel to car, which filled the pump side enough to prime it. Car started, problem solved.

turbo97se

I saw this too late .. the procedure is similar to the following DIY on an E55 AMG.
Mine is leaking and is not covered by MB USA warranty as most petrol engine cars which is annoying.

Can I ask where you bought your sender? I am going have to go through this again.

https://mbworld.org/forums/w211-amg/...ation-diy.html

unhcampus

I purchased everything from the dealer.

turbo97se

Wow! OK thanks for the reply. I try to avoid the Dealer .. unless you know them very well (or happen to work there), they're prices are pretty high. I have seen these on-line for like $260 shipped for OEM. The other place I shop these days is OEDiscountparts.com for Genuine MB Parts for like $450 or so shipped.

turbo97se

Thought I would update here.

I had a dreaded fuel leak from my sender. This is common on almost all W211s. Mercedes has a recall campaign to fix most of them but it is all VIN dependent. Mine was not covered ... just my luck. On my E55, there were cracks in the sender and I replaced the driver's side one out of my own pocket. The passenger side one I JB welded since it had not broken through all the way yet. I could have replaced the entire sender as it's not terribly expensive at around $200. However, I am concerned after replacing that the plastic may break down again eventually. This layer of JB Weld should protect the plastic from the fuel. Hope this helps someone:

Below is a picture of the leak itself (from my E320 CDI):



I believe the gasket was the leaking but not wanting to risk putting it back and have it still leak, I decided to coat as much of it as possible with JB weld. I "watered down" the JB weld with Acetone and poured into the inside of the sender coating it, letting it sit and layering it a couple of times. I also did the top side but avoided the locking ring area and seal contact surfaces.

Here is the bottom side of the sender coated:


Here is the top side:


Then I used Permatex Ultra to seal the rubber gasket.

The result after 3 months ... no leak. It's not pretty but now I can fill the tank and have peace of mind that there are no leaks. Cost was $10 for the JB Weld, Acetone I already had and $5 for the Permatex Ultra.

Carsy

Well done , looks to be a good product. JC

Micah / AF1 Rac

Oh the irony...timing is everything. I'm pretty sure my in tank pump is going, or at very least the relay powering it. I've also got a little leak under seats if car is truly TOPPED OFF on fuel. Wife was driving it last week, said check engine light came on, followed by reduction in power, her words were more like "a little laggy". I've got an ODBII tool that works very well on the W211/OM648 so I hooked up, got code for low rail pressure, reading directly off the rail pressure sender though everything looked good, the same basic 5000 psi at idle and almost 27,000 psi at full power that it has been for the last 100k miles or so. I drove the car for a week with zero issues until today, cranking time is a little longer than normal but then all seemed well, until the first big hill coming back from lunch, no smoke, just drop in power and MIL came on at once, scrolled over to live data and obvious issue, max pressure was about 16,000 psi...stopped, turned off car, reset MIL...drove normally up to 26,700psi pressure for about five miles...then...MIL, loss of power etc.

It seems pretty obvious that the mechanical pump is fine and the high pressure regulator mounted on the rail is working fine...longer crank times and random loss of fuel pressure sure seems electrical, like the in-tank pump. I've gone 177k miles so far on this car so it's not exactly shocking, the pump cartridge needs to be replaced anyway due to leak at sealing ring or possibly a crack in the plastic body.

So what say you Benz guys, best place to order part? 06' W211 3.2 CDI. Other than a new relay, any other parts I should add to that order...as it sits it's fuel pump/sender cartridge, spare sealing rings and a relay. I'm internally debating the rail mounted pressure regulator but, if it isn't broke, I don't plan on fixing it.

Thoughts? Sound logical. All services up to date, all injectors good, no Black Death issues, EGR deleted a long time ago and no intake flapper functionality with my mapping, just for background.

Micah / AF1 Rac

Well, $268 to my door from the Benz web masters. Done. Btw, fuel leak fixed by simply tightening the extra cap on he passengers side. At this price, if I'm wrong...well, I'm wrong. I'm used to being wrong.

josh8loop

I am a big proponent of installing a fuel pressure monitoring Tee between the fuel tank and the inlet to the fuel filter. This would assist in sorting out any in-tank fuel pump issues. Obviously if you are hearing strange noises from the pump that's one thing, but sometimes you don't hear anything unusual and it doesn't perform correctly. For $268.00 and after 177K miles that's not too bad

steeven001

Does your fuel pressure go up to 27,000psi because of the green diesel engineering tune? Under full load my fuel pressure maxes out at 23,000psi which is what is stated in the repair manual. I have an upsolute tune but I guess they don't raise the maximum rail pressure.

Sorry about going a little off topic.

turbo97se

So just a headsup/clarifcation .. and maybe you know this already ... the part I fixed was the fuel sender not fuel pump. This is on the left hand side of the car (behind the drivers seat). The electric fuel pump is on the the right side of the car. Could I ask where you got your electric fuel pump for $268 shipped? I am not sure what Benz web masters means. Normally, I think they are $400 or so. Just be wary of aftermarket parts that are incorrectly labelled as being compatible when they actually are not. Typically they will fit the gasoline model but not the Diesel. Just a note of caution here. Let us know how it goes.

Micah / AF1 Rac

Sorry on pressure, in reviewing data 23,780 psi was highest shown in full boost acceleration run in top gear, at about 30 psi peak boost, or as my display reads 88" of Mercury vs barometric pressure of 28.9" of mercury on the stormy day it last ran perfect last week. The GDE reflash bumps fuel rail pressure only slightly, from a stock target of 23,000psi to 23,650 psi. To safely go much higher than that or increase flow much over these numbers your CP3 pump needs to visit a specialty pump shop, by stroking the plunger pistons and cam in the pump a bit about 20% more fuel volume is easy, going from 10-12mm pistons, then stroking those these pumps are pretty safe to 27,000-30,000 psi at about a 50% volume increase. Im only shooting for about 300 bhp in the end, stock pump at 23,650 or apparently 23,780 will be fine.

Now back to the fuel pump in need of fixing. I used Jack Ingram Mercedes webstore. Been dealing with Caleb there and as the price seemed too low I included VIN and a few pics, needless to say he got back to me yesterday with correct part number, total price ended up being about $500 shipped. I knew $268 shipped had to be wrong. Caleb has been great so far on communication, Jack Ingram definitely earned my shout out, my local dealer just assumed I'd be willing to drop over $1000 for the same part, those guys are driving my non warranty business far away with each new experience. Genuine Mercedes part btw, not aftermarket.

My blanking cap or sender cap was leaking like holy hell too with a full tank, I ordered a few gasket rings but as I was putting car back together to wait for parts to arrive it occurred to me to check how tight the sealing or locking ring was...zero tight, I mean, at least two turns from having ANY sealing tension on it. I tightened as much as I could by hand, like magic, not one more seep or drop of fuel came out....hmmm, just a heads up on this one.

On the W211/e320 CDI only the left side tank opening is really used, the right side as basically a cap to cover hole and ease access as you snake through the line assembly it seems. Your E55 is apparently different. Both the pump(s) and sender/level sensor are located on left. Pics to follow, crappy phone pics but better than my misconstructed early am post storm chasing words.

Micah / AF1 Rac

Apparently this version of forum software is allowing only one post per pic...so here is another

turbo97se

OK Cool .. that's what I figured. I ALWAYS check the electronic parts catalog based on VIN. There are few things you cannot check or get on EPC. You can see the fuel pump part number is 2114705894 from the extract below

I am aware that the E55 and E320 CDI are quite different in just about every way as far as fuel management is concerned. But the basic layout is the same and replacement principles. The Electronics are pretty much identical ... I am more comfortable with W211 than probably almost any other car ... except the E46 M3 and Lexus IS300... but those are much simpler cars. By the way on the W211 E55, there is a sender on the left (a rather complex one compared to the CDI) and dual fuel pumps with another sender on the right side. You can check out my DIY below for some of the details:

https://mbworld.org/forums/w211-amg/...ation-diy.html

As far as online retailers is concerned, I used to use Mymercedesparts.com which were essentially MB parts in Atlanta and had the best pricing overall and super cheap Fedex 2 day when I needed something. Unfortunately, they are no more. Now I am trying Huskerparts.com based on others recommendations .. so far pretty cheap on price and reasonable shipping, making them my choice. They would be ~$423.09 shipped.

If ever you need a part number checked, I'd be happy to check it out for you. Having the part number on hand is key and you can search many internet sites and then ask if your guy is willing to price match. Surprisingly they often will. Sometimes, I will approach FCP Euro and ask them if they will price match and many times they will match online real dealers ... plus they offer lifetime warranty on their parts ... something to think about also. I use FCP on Audis mostly - whose parts are expensive and are notoriously unreliable.

BenzKraft

Hello Micah, so what ended up being the cause of this issue you had with the low rail pressure code and loss of power? I have the same problem: I drive the car for a while until it warms up then at higher speeds or power demand it goes into limp mode or lacks substantial power. I get the 2633 (Fuel pump control circuit low) and 2624 (Injector control pressure regulator circuit low) codes. I'm guessing my fuel pump is failing and I'm planning on testing the pressure to verify it before buying a new one at $650+. I'm also not sure if there is a mechanical fuel pump closer to the engine besides the in-tank electrical one.

Any feedback would be very helpful.

Cheers.

Micah / AF1 Rac