e500slr

Hi guys,

I recently bought a salvage W212 E63 to take the engine from to repair my W212 E63. The salvage car was running fine a few days ago everytime I started it. I started it a couple of days ago, it ran fine and then turned it off and started it again. It started for a second, just and then sputtered a bit and died.

Now I took off the end cap for the fuel rail where you measure fuel pressure (the valve). I put the car in key position 2 and then pressed that valve. No fuel sprayed out meaning there's no fuel pressure.

What do you guys think, dead fuel pump? Relay (I checked some of the relays but couldn't find a relay diagram)?

I want to test the fuel pump directly by putting 12V on it. Is this a good idea and does anyone have any idea which wire is + / -. There are 5 wires, 2 thin and 3 thick. It's probably 2 of the thick ones but I don't know which ones. If I tap 12V and don't get fuel pressure then it's definitely the pump right?

I appreciate the help guys.

BoostedAero

Prolly not a good idea to add voltage directly to the pump the test. I would test the pin connector that leads down to the pump with key position 2 then with meter plugged up and sitting in your lap showing current draw start the car and see what voltage is coming across. No voltage walk it back to the pump relay, inspect wiring there. If relay and pumps have wiring that is clean and uncharred and relay is good. That would lead me to pumps, or a clogged fuel filter.

I am a e55 guy and assuming that the e63 would be similar. You should be able to hear the pump prime with rear seat up and cover off. If not check voltage of wiring and relay first. Then isolate clogged filter/ dead pump

hope that helps

e500slr

I just did the voltage test. There were 3 thick wires and I tested them all, so 3 combinations and nothing. I actually cranked the car so it definitely should have been giving voltage.

The problem is, I can find alot of info on W211s but I just can't seem to find the damn relay schematic for the W212. There info on the fuses but not the relays. I'm flabbergasted, this is not a new car.

Could it still be the pump if the wires leading to it aren't getting voltage?

I actually swapped out the fuel pump control module with another and tried, still nothing.

BoostedAero

I would check in the w211 location where the fuel pump relay is located, it is opposite of the rear SAM (fuse box in trunk). You will have to remove the trunk fabric that makes up the passenger side of the trunk and the relay will be located near the right rear shock pillar. Check there for the relay, the location more than likely has not changed

e500slr

Thanks alot for your help BoostedAero I solved it but it wasn't any of those. Mercedes, bless their hearts, decided not to put an accurate fuse list in the paper that comes with the car. I discovered there's another fuse in the rear SAM module that is for the fuel pump. There are ALOT of the fuses allocated to the fuel pump (and other components of course on the same fuse). The lazy ***** that I am, I only checked the fuses allocated to the fuel pump by that paper but the link below has the full information on fuses. I'd like to thank Mercedes for the inaccurate information and I'd like to pat myself on the back for my laziness that wasted me alot of time.

Thanks again BoostedAero for the help and input

I'm glad that nothing is wrong at least

Here's the link for the full list if anyone ever has the same problem and reads this:

http://www.mercedesmedic.com/e-class...ram-2010-2016/

By the way to anyone wanting to check if the pump is working or not. The fuel pressure valve on the middle left side of the engine at the front (protected by a brass looking closed nut) can be used to check if there is fuel pressure or not either with a pressure gauge or simply press your nail and see if fuel squirts out (be careful, do it lightly as fuel will SQUIRT out and do not have any flames or sparks nearby, this is not the recommended method but it shouldn't be any problem if you're a grown up and have a little common sense).