power to fuel pump relay 91 190E - PeachParts Mercedes-Benz Forum

just-n-time · #1 03-12-2012, 02:58 PM

Car would not start this morning, cranked over but did not start. can not hear the pumps. I pulled the fpr and put my test meter on terminal 7 then 8 and found no current. I need to find the source of the power to be sure that I have continuety. can some one direct me? thanks memory. car is a 1991 190E 2.6

mbdoc · #2 03-12-2012, 04:30 PM

Fuel pump relay is part of the MAS relay assembly.

Pins #1 & 2 are for the fuel pump.

just-n-time · #3 03-12-2012, 05:08 PM

Quote:

Originally Posted by mbdoc

Fuel pump relay is part of the MAS relay assembly.

Pins #1 & 2 are for the fuel pump.

I removed the fpr and put bat curent to pin 7 and had no reaction at the fuel pumps. I checked the terminals at the pumps and had no power at either pump, but you are saying pin 1&2?

JamesDean · #4 03-12-2012, 05:24 PM

Yes, Pin 1 is +12V and Pin 2 connects to the fuel pumps (or vice versa). So If you bridge these two pins the pumps will kick on, you should be able to hear them.

mbdoc · #5 03-13-2012, 08:25 AM

jnt,

There isn't a seperate fuel pump relay on a 1991 car.

Like I suggested, the fuel pump is done thru the MAS relay, jump pins #1 to #2 and the pumps should run.

just-n-time · #6 03-13-2012, 10:31 AM

Quote:

Originally Posted by mbdoc

jnt,

There isn't a seperate fuel pump relay on a 1991 car.

Like I suggested, the fuel pump is done thru the MAS relay, jump pins #1 to #2 and the pumps should run.

thanks doc, will check the harness today. need to figure out why it lost power to the pumps. by the by i did power #2 and the pumps are good.

just-n-time · #7 03-13-2012, 01:27 PM

Quote:

Originally Posted by just-n-time

thanks doc, will check the harness today. need to figure out why it lost power to the pumps. by the by i did power #2 and the pumps are good.

Testing the Harness On testing I found that power was at #30 using the harness ground I had power at the 30 post no other poles had power. But when I use a jumper to the OVP at pole 15 I had power to post30 and 31, in my thoughts I have power to ground is this wrong or is the OVP shorted? No power has gone to poles 87 when jumper is used.

the test for key off was as stated with key on I had power to post 15.

just-n-time · #8 03-14-2012, 10:18 AM

Power to the poles of the OVP [7 pin] style first the harnes at the 30 pin is hot at all times, Pin 15 hot with key on. 30a ground, when ground is applied to this post and power applied to pole 15 the electro magnet pulls in to apply power to the 87# pins when testing the OVP on the bench you will have to use this guide to check propper function of OVP.

JamesDean · #9 03-14-2012, 11:46 AM

This might be helpful:

just-n-time · #10 03-14-2012, 12:40 PM

thanks james will look it over

just-n-time · #11 03-27-2012, 05:39 PM

OK just an update, I replaced the OVP with the new style I now have fuel pumps working. found that I have fuel at the top of the injectors after cleaning the fuel filter at the fuel inlet hose ( I did take the fuel distr. apart and I am sure that several springs are in the wrong place) but I have fuel flow to the injectors. I still could not get fire even when I used starting fuel. So I replaced the cap and rotor, now we don't have good spark we have great spark. still no fire or starting. the fuel must be the culprit tomorrow I will pull an injector and see if I am getting spray out of it, if not i may have fuel differential problems from top and bottom chambers.

mespe · #12 10-12-2013, 02:34 PM

Not sure if that MAS drawing applies to the 2.3

Pins 1 and 2 of the 003 545 20 05 relay are plugged on the connector.