SyHS

I recently picked up a 2004 Midnight Blue E55 AMG.
I knew when I was getting the car that it was having trouble accelerating. Upon picking up the car (with 3/4 gas) it was bogging/sputtering upon giving it more than 50% throttle. I come from the Evo/4g63 world and when this happened on my 730bhp Evo IX it was due to poor plugs or improper plug gap. I end up slugging it back home which was about a 150 mile adventure. I get to autozone before stopping home to pickup a set of spark plugs that I could change once I get into my garage. They didn't have 16 in stock so I end up leaving. Once I hop into the car it has about 1/4 tank of gas left. I tried to start the car and it turns on for a second and revs to about 4-500 and it shuts off. I'm unable to give it any gas, however once the car stalls out the starter keeps on grinding like it's trying to catch.

I eventually let the car cooldown and it starts right back up. I give it a little gas and it starts to bog/sputter upon just about any amount of acceleration. I pull into the gas station and fill it up. It starts up right away and as I pull onto the sideroad I gas it and it pulls like a train. After a 2 ticks of the gas gauge went down it started to do the same thing where it bogs down upon acceleration like it wants to go but it's being starved and unable to.

I'm assuming it has to be fuel-related but I'm not sure exactly what part of the fuel assembly would cause this issue, or if it could just be a sensor somewhere.

The car has a 78mm pulley, headers, exhaust, tune, 010 pump, heat exchanger, and a few other mods... It made 490whp/545wtq on the dynojet.

Sorry for the poor grammar/sentence structure, I've had quite the long day lol.

Any input on what it could be would be greatly appreciated so I have somewhat of a heads up on what to spend.

Bankroll

I would start with fuel pressure test, and also take a fuel sample. Scan data, and codes. The data to focus on would be MAF signal, HO2 sensors,(B1,2, S1), and my favorite, long term fuel trim, bank one, and 2.

bbirdwell

Fuel pressure schrader valve is on the passenger side front of the fuel rail. Pressure should be around 5.5 Bar or 81 psi at idle.

The fuel system on the E55 can be problematic if not properly cared for with preventive maintenance. Check out the following for some additional information.

https://mbworld.org/forums/w211-amg/...intenance.html

https://mbworld.org/forums/w211-amg/...ify-parts.html

Go with the Bosch plugs when you replace them. Be advised the spark plug wires are multiple lengths so don't pull them off the coil packs unless you lay them out in proper order. A Mercedes spark plug boot removal tool makes the job much easier.

Let us know what you do to resolve the issue.

cosmosschwarz

Are you in the US? Has the fuel pump recall been done? It's covered under warranty if it's the pump issue. Pull the rear seat bottom and see what the plugs on the top of your pump/sender hats look like. If they're corroded or there's fuel present after filling the tank all the way up, new tank assembly with pumps will be covered under the recall at the dealer.

SyHS

Did a fuel pressure test... 40PSI across the boards so I popped up the backseat to inspect... It looks like the fuel-sender unit behind the passenger side is leaking. The recall was done in 2014(fuel tank replaced)... It does not say if the entire assembly was replaced with it though. I called MB to see if they would cover it since that unit is obviously leaking once the tank gets filled up. If not I'll end up buying the assembly and installing it myself.

I'll leave the thread open. Once I replace the lines and unit I'll update it if it fixed it. If not it could be misc sensors that went bad after running lean for too long?

Thanks for the responses everyone.

cosmosschwarz

If it was done under the recall then it should have been a whole assembly(new tank comes with pumps). And it's still covered if it's leaking again, call your dealer.

SyHS

Ive been calling around to local mb dealerships. They are claiming it was done, however the car is now out of the warranty and they are unable to fix it unless I can take it to the dealership that originally did it and have them say it was a faulty tank/poor installation. In for a massive headache but not much I can do besides waiting for them to call me back...

cosmosschwarz

Warranty was extended to 15 yrs so it would depend on your production/in service date. Attached the document from Mercedes.

knowbenz

How bad is it leaking? Enough to drop pressure that low? Make sure both pumps are running. Make sure connector isn't melting.

SyHS

the connector was melting, had to order a new fuel setup and the correct wires/relays. Should be here by Tuesday/Wednesday and I'll have it up and going hopefully by Wednesday night or Thursday.

Do you happen to know what part number the gasket and lid for the fuel pump is? I might as well replace the seals and spincap while I'm in there

bbirdwell

211-471-05-79 Fuel Sender Seal x 2 each.
About $15 each.

001-990-80-54 Fuel Pump Assembly Lock Ring x 2 each.
About $5 each.

Joseph Adam

sorry to bring this back after so long, but did replacing the fuel sending unit fix your sputter issue?