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1994 E320 Wagon - Fuel Pump no power?

10K views 5 replies 3 participants last post by  LeftCoastGeek 
#1 ·
I removed fuel rail to replace O-rings on injectors. Batt went dead while doing the work as I was listening to radio while working. I jumped car to restart after I was finished my work. Fuel pumps don't make noise when I turn key on. Car cranks but no start, no fuel in rail. I replaced OVP and Fuel Pump relay behind battery. I charged battery but no matter how many times I cycle the key, I don't hear noise from fuel pumps anymore. Any ideas guys?
 
#2 ·
ECM needs to see pulses from the L5, the crank position sensor (CKP), to fire the fuel pump. fuel pump power comes from X4/10, which is right off the battery, that goes to K27, the fuel pump relay, the ECM turns that relay on when it sees pulses from the CKP, and that relay sends power direct to the pumps.

you could try pulling the fuel pump relay, and jumpering its socket, pins 1-3, that should fire the fuel pumps up even if the ignition is off...

http://new.freescruz.com/.priv/W124/w124CD1/Program/ETM/24072001.pdf
http://new.freescruz.com/.priv/W124/w124CD1/Program/ETM/24072002.pdf
 
#3 ·
Or alarm and imobiliser fault . Check all your fuses in fuse box , before you operate on the injection or CPS If it is the CPS you can tell by looking at the revcounter if it moves and as you try to start it up .No movement , then yes CPS is suspect You have replaced the fuel relay this you did say .. But do let us all know how you get on.
 
#4 ·
I feel a little intimidated by those wiring diagrams...:crying

I found a second fuel pump relay under the cover behind my fuse box and its fuse looked ok. In the picture on the side of the fuel pump relay there are no pins number 1,2 or 3. They are numbered 30, 86, 87, etc.
But on the side of the OVP there are. I will check the tach when I try to start the car as suggested to rule out CPS.

I thought immobilizer/alarm would stop it from cranking at all?

I appreciate you all's input, I will take my time and try to understand what all of this means.
 

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#5 ·
UPDATE:
Jumped pins on fuel pump relay and pumps started up, even with key not in ignition. I took the power off right away because i could see smoke.
tacj does not move while cranking as suggested before to rule out CPS.

Bought new CPS and will try and get that replaced later today.
Might as well do my neutral safety switch while Im under there
 
#6 ·
that first relay in your pictures is the 'OVP', Overvoltage Protection relay. its job is to shut off all the electronics if the system voltage goes too high.

avoid URO brand anything, its chinese junk. most of the Mercedes OEM relays are KAE or Stribel.
 
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