I just acquired a 1992 940 turbo. The car had been abandoned and i know nothing of its history. It had been sitting for about 8 years
I pulled the in tank fuel pump out and it was dry and split so i replaced it. I pulled a fuel pump relay out of a running car and still no power to the pump.
I have voltage to terminal 30 of the relay. I have noticed there seems to be no power to the ac controls and the radio also. Dont know if these problems are related.
Maybe the ecu?
Do any of you guys have any idea?
Thanks
Mike

 

fuel pump power comes from the fuel pump relay, which is controlled by the ECU the fuel pumps are only powered while the engine is turning over, and for about 1 second when the key is first switched on.

 

you can also bypass the FPR to test the pump. Pull the relay out and jumper the two large spades to emulate the running engine

 

the logic that stops the pumps when the engine isn't running goes something like this...

1) CPS (crank position sensor) is read by the ICU (ignition control unit), which passes a cleaned up version to the ECU (fuel injection control unit)

2) ECU sees no timing pulses for a second or so, and shuts off pump