gordyboy

Had all the symptoms of a bad fuel pump so I replace it. After the replacement it fired right up for a ride around the block. Then it sat for a few weeks. I tried starting it 2 days ago and it won't start, same symptoms as before I replaced the fuel pump. The pump is getting 12 volts and when I hold it in my hand and have someone jump the DME relay I can feel it torque like it wants to go but it doesn't. Putting a meter on it, the voltage drops from over 12 volts to under 11 volts when the pump is trying to run. I pulled it and put it on the bench. When I give it 12 volts it does the same thing it did installed but if I up it to 15 volts it runs fine. I ran it for just a few seconds to make sure it seems to work, don't want to run it dry.

Sign of a bad fuel pump? Or do you think I have some other problem?

Mike951

FWIW I recently had a no start issue on a 951, was about to pull the fuel pump down and check voltage on it, etc., but first I grabbed a DME relay from another car, popped it in, and the car fired right up. DME relay was faulty... If you have anothre one, maybe try that. Probably the easiest fix if it turns out to be bad.

-mike

peanut

to test the pump in situ you should remove the DME relay and replace it with a 3x way bypass terminals 30, 86 & 87b ( this will bypass the ECU unit and run your fuel pump continuously and supply your injectors .)

When you first switch on the ignition the ECU earths the supply to the fuel pump for one second only allowing the fuel system to pressurize to assist starting.

Your pump won't start again until your ECU receives a 200rpm cranking signal and all the other sensor inputs at which point it triggers the DME relay to supply the injector pulsing and fuel pump supply for running

gordyboy

Thanks for the replies, I always learn something from them even if it isn't ~exactly~ what I'm looking for :-)

I tried a spare DME and it didn't help. I also jumpered the DME, it didn't help. In all cases I confirmed that I was getting 12 volts at the pump. Then I removed it from the vehicle and put 12 volts on it from my truck battery, it didn't help. Then I put it on the bench and put 15 volts on it and it seems to run fine.

I have another pump on the way. I sure hope that's the problem.