no power to fuel pump

[Turbogsxmitsu]

i recently bought a 1991 talon tsi, i bought it with a bad ecu, i replaced it, now it has no fuel, the person i bought it from replaced the fuel pump, i checked it, it works, i checked to see if there is power to the pump and there is nothing. i cannot find anykind of fuse for the fuel pump, where should I look? What could it be? :thumbdown

 

[steve]

There isn't fuse specificly for the fuel pump. The MPI fuse on the positive battery terminal is used for the pump if it hasn't been rewired with a direct power source. The MPI relay switches the fuel pump power. Keep in mind that the pump is only powered when the ignition switch is in the start position or by the ECU when the car is running.

Steve

 

[Turbogsxmitsu]

the fuse on the positve battery terminal is fine ( for MPI). The ecu that was sent to me ended up being for a 1990 fwd 5spd turbo, not what I needed awd auto 1991. Do you think this would keep it from getting fuel completely? Let me know thanks

 

[steve]

No, there are two wires that are different between the two and neither has anything to do with turning the fuel pump on. http://www.ecanfix.com/~mdhamilton/ecuwiring.html

Steve

 

[Turbogsxmitsu]

then what could it be? Do you think its the FP relay, the guy before me had it fixed?

 

[steve]

The MPI fuse on the positive battery terminal is used for the pump if it hasn't been rewired with a direct power source.

Crap, I must have been still asleep at 10am yesterday. The fuel pump power comes from the ignition switch IG1 terminal (fused by the 30A IGN on the battery terminal) to pin 3 on the MPI relay, switched to pin 2 and off to the pump. NOT from the MPI fuse.

http://www.taboospeedshop.com/wiring.htm

then what could it be? Do you think its the FP relay, the guy before me had it fixed?

I have a couple of ideas.
What I see alot is ECUs with the fuel pump control line damaged from cap leakage but that causes the car to start but die seconds after you release the starter.

To check the fuel pump circuit first measure the resistance between 9 to 6, and 3 to 7 on the MPI relay to make sure the coils haven't opened.
Make sure MPI relay pin 6 is grounded.
Check for 12v at pin 3 on the MPI relay when your ignition switch is set to RUN. (this comes from IGN fuse to the ignition switch to the MPI relay)
Check for 12v at MPI relay pin 9 when your ignition switch is set to START. You should also see 12v on pin 2 at this point and the pump should turn on. If you have 12v at pin 9 but not at pin 2 the MPI relay isn't switching. If you have 12v at pin 2 but the pump isn't running you have a bad pump or the wiring is open.
With the ignition switch in RUN try grounding pin 7 and check for 12v at pin 2. This is the other way to switch the MPI relay and how the ECU keeps the pump on after you release the starter.

Steve

 

[Turbogsxmitsu]

Thanks I will try this weekend

 

[Turbogsxmitsu]

I found the problem, the shop that had the car before me put a fuel pump relay in, but never made the conectors snap together, so it looked conected but wasn't, what a bunch of assholes!!!!!!!!

 

[steve]

Cool,

Do you still have the original dead ECU? I always need dead ones

Steve