jay m

I have a 2003 w211 E320. I need to replace the fuel pump and cannot find the directions mentioned by a member on another post. Thanks for your help. Of course it is at the grocery store broken down now. Figures.......
Jay

Plutoe

Send a PM to member "Konigstiger" who has access to the repair docs, if not spend the 20 bucks for a 24 hour subscription to startek WIS-----you can learn loads about your car in 24 hours!!

jay m

Thanks for the info. Got back in the car after shopping and it will start up, running really rough for a few seconds, and the engine will quit. I will search for the information on testing the crank and cam sensors before replacing the pump. thanks for the help.
Jay

jay m

I replaced the fuel pump and it ran fine for 3 months. The new pump has now quit working! Replaced it with a fuel pump from the dealer again this past week. The newest one worked for almost a full day before failing! I have not had a chance to check it out completely. Has anyone else heard of fuel pumps failing so soon? Is there something I am missing here? Thanks, Jay

novae500

several things to check if you replaced the fuel pump:

-fuel pressure at the fuel rail port
-fuel relay in the trunk, towards passenger side, see if still good or fried
-which side fuel unit was replaced? Passenger side or driver side? Driver side fuel filter/sending unit may have a float that is stuck and not letting fuel go over to the passenger side where fuel pump is
-possible installer error by not connecting the two pumps connections tight within the tank.

jay m

I replaced the one on the passenger side. Twice.. I will check out your suggestions. Thanks!! Jay

jay m

Got it.......I think..... I took another look at the fuel pump and while I was checking the electrical connector I heard a snap, as though the connector was not fully engaged. It started working again. I put it all back together and have started it numerous times and took a test drive. Thanks Novae500!! for the suggestions. The pump I installed 3 months ago was a Bosch after market from Quintanaauto in Florida through EBay. I have called numerous times without an answer and also left a message. No response. Beware. This current pump is from the Mercedes dealer. thanks again. Jay

jay m

Never mind. Not working again. It must be a faulty pump. I am going to take it back and get another one. It has a 1yr warranty. It may be a couple of weeks before I am able to get down to the dealership to swap them out. I will try to remember to give an update. Jay

jay m

Can anyone tell me which wires I need to use to test the voltage to the fuel pump while spinning the engine over and where to tap into them for the voltage test? Thanks jay

Plutoe

The rear passanger side pump should have a five pin connector---pin 5 is brown wire and the pump ground; pin 2 is red green wire and voltage in.

jay m

Thanks Plutoe!!!Found it. I used the body as a ground and as soon as I touched the volt meter to the red green wire, i found 12 volts, the fuel pump started working again and the car is running...very strange. I wonder if I need to find all the ground points on the vehicle and clean them? No idea..... thanks jay

jay m

Thanks again novae500 and plutoe!! Everything worked fine until I filled up w/ fuel. After I returned home and let the car sit overnight, it would not start again. After suspecting the drivers side fuel sending unit, I removed the large nut, siphoned out about 10gallons of fuel, and gave it a good wiggle and shake. The pump began working again. I will order a new unit and give an update. I believe this should solve my problem. Thanks, Jay

jay m

I replaced the unit on the drivers side and all is well. Just wasted cash on the second passenger side pump purchase. Oh well, that's definitely not the first time for that type of mistake. Thanks guys, Jay.

jay m

The pump quit again a couple of weeks ago. After much probing with a multi meter, I located the problem.......almost positive....maybe. I was loosing ground voltage on the drivers side aux pump 5 pin connector. The brown wire. After taking a close look at the both sides of the connector, I noticed that during the mold injection process the plastic was coating the bottom part of the knife connector. The plastic had melted undoubtably from heat caused from not making a good connection and migrated into the connector on the wiring harness. I used a scalpel to remove the plastic from the pump side connector and a tiny pick to remove the plastic from the wiring harness connector. All has been well for the last 2weeks and 300 miles. This is long winded explanation....hope it can help the t next guy. Thanks, jay

noud

I have same 03 E500 and had faulty fuel pump few days ago. On early 2003 E class pumps were coming as one assembly, and now they made conversion kit for new revised pumps. So simply if you have old pump from factory you cant just replace one pump, you should replace everything, otherwise it wont work, so simply if you have bad fuel pump (doesnt matter which side) you should buy two revised updated pumps plus conversion kit (wire harnesses and brackets).

john0183

Hey noud where do they sell those types of pumps and how much are they.

buildingmuscle1

Does your fuel pump comes in 2 pumps running a cross from each other on the back seat what is that second pump thanks in advance

jay m

The unit on the passengers side is the called the fuel pump assembly. The drivers side assembly is the sending unit. Either unit is sold separately. There is an adapter harness that can be purchased to allow you to use the old style sending unit (drvers side) with a new pump unit (passenger side). I wound up replacing both units. I fixed the trouble I was having with the bad ground connection by disassembling the 5 pin connector to the drivers side pump and squeezing the female ground pin (brown wire) connector together for a good snug fit. Running great for months now.

jay m

Oh yea, To answer your question about the function of both pumps.... The tank is a saddle tank with a hump in the middle which needs fuel transferred from one side of the tank to the other so that the engine can utilize all the fuel in the tank. Otherwise there will be unusable fuel that is trapped on one side. There is a float level on both units that somehow assures that the fuel on both sides of the hump remain relatively equal. Jay

gunmetalg35

I changed pumps and relays. Car ran for few more weeks then the sending unit relay went.....after replacing that....no start. checked the sender tank....shook the harness and it cranked.... GROUND!

Im looking for the short...or maybe harness.... anyone with the same issues.... get a fix?

PLEASE HELP