e550 no start fuel issues?
I found the fuel rail to be completely dry.
today I jumpered the fuel pump relay, and behold the car started.
I ordered the new relay, but when the car started, it was missing quite badly. I ran the engine for a while, and revved it up to 2400rpm where the miss is almost not noticeable, and let it idle, and still it runs rough. Now I am puzzled.
What does the fuel relay have to do with the car running rough?
PLEASE what else could cause this?
The pump is not being turned on without the jumper wire.
When the jumper wire is installed, I can drive it normally.
The jumper wire is working, so i guess its not a pump plug issue?
Just trying to figure out what send the signal to the pump to run, I will multimeter it tonight to see if it is sending a signal at all.
Last edited by scoobertdoo; Jun 2, 2016 at 02:11 PM.
The activation prongs on the relay are showing 10 volts.
When going from the ground on the activation prong to the pump wire I also get 10 volts.
When I go to the ground bolt next to the trunk panel I get 14 volts.
So does this mean I have a bad ground?
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The day before we took a 400 mile trip, and went thru a lot of rain on the way home.
Then the next day it didnt start. What is the chance that I just hook up a new ground to the back of the box that it would have enough voltage to work?
Car started.
So this whole thing was a ground issue???? Going to wait for the car to run normal again, then call this issue solved. the fuel rail is still draining after its done running for some reason.
Now I have to tear out the trunk lining, and run a proper ground wire I guess.,
Last edited by scoobertdoo; Jun 2, 2016 at 04:32 PM.
how did you ground the wire? I'm having the same no voltage to the fuel pump problem. I also have to use a jumper wire for the fuel relay rear sam. I tested the pump and relay and they are both good. Thanks for your help in advance!
Car went to the junk yard. Parts are so expensive, and labor too. So many electrical issues, and so much money wasted on a pos car. One will start, and you will have the next issue, and the next.
I have run into a ton of people since then that all say the same thing. Never buy a merc out of warrantee. I keep hearing issue after issue. I guess the old 300 diesels were the last ones anyone should buy that will last a long time. I keep hearing about electrical gremlins, constantly. I do however love the youtube video about buying one from carmax with an extends warrantee. One guy said he cost them $14,000 in repairs over 2 years :P






hahaMercedes: first vehicle ever made
Mercedes: biggest POS when something is wrong to the average owner
Mercedes: greatest thing ever when nothing's wrong



its all an opinion ha. lemonsqueezyyyyyy
When you say engine module, are you referring to ecu? Mine , works fine usually after I use a jumper wire in the relay spot. I have the seat out and have been finally listening to the pump prime one I place key on position 2. Seems like it's working now, I'll keep testing it for the next few days.
When you say engine module, are you referring to ecu? Mine , works fine usually after I use a jumper wire in the relay spot. I have the seat out and have been finally listening to the pump prime one I place key on position 2. Seems like it's working now, I'll keep testing it for the next few days.
Mine is a 07 e550 with 107k on the dash, could I just create a ground wire for the relay in the trunk? Buying another ecm is pretty expensive for that model. Are there any write ups on the remedy, furthermore how were you able to fix yours?
Thanks a bunch brother!
Mine is a 07 e550 with 107k on the dash, could I just create a ground wire for the relay in the trunk? Buying another ecm is pretty expensive for that model. Are there any write ups on the remedy, furthermore how were you able to fix yours?
Thanks a bunch brother!
when I use a jumper wire, have the engine running for 10-15 minutes ( if I plugged in the fuel relay it would then prime and start ) however, by the following day, there would be no signal to the pump meaning I guess no ground to the relay. (Both ignition power and 12vconstant has power) Did you have these symptoms as well? Thx bro
when I use a jumper wire, have the engine running for 10-15 minutes ( if I plugged in the fuel relay it would then prime and start ) however, by the following day, there would be no signal to the pump meaning I guess no ground to the relay. (Both ignition power and 12vconstant has power) Did you have these symptoms as well? Thx bro






