Resolved 2G No power to fuel pump.....

[Dihtung Glava]

I'd also like to know the wiring issue...

- I jumped my pump with 12 Volts, it runs no problem
- I powered it through the test connector on the firewall, runs no problem
- I tested both relays behind the radio as per the Haynes manual, both passed

For some reason connecting a probe tool between one of the relays and the chassis also powers up the pump.

Cranking the ignition - doesn't power up the pump. Do I have a bad ground somewhere? What else can I even check?

 

[HaveBlue83]

I'd also like to know the wiring issue...


For some reason connecting a probe tool between one of the relays and the chassis also powers up the pump.

Sounds like u grounded it and then it ran. Check relay grounds

 

[Dihtung Glava]

Sounds like u grounded it and then it ran. Check relay grounds

How do I check relay grounds? So far I've been going around and just checking every ground on the chassis in case I forgot to attach one... everything seems to be connected.

 

[steve]

https://www.dsmtuners.com/threads/2g-basic-ecu-mfi-mpi-relay-circuit-function.497188/

Special attention to the Fuel Pump function.

 

[Dihtung Glava]

Thank you Steve, solid write up. After reading this I believe the MFI relay is working correctly - I hear it click on when I turn the ignition to ON and I hear it click off a couple seconds after I turn it off.

The fuel pump relay might be acting up, I don't hear it click with ignition at ON or while cranking. I tried removing it and jumping pins 1 and 4 with a wire - fuel pump starts running with ignition ON.

I feel like this means I'm not getting ground from pin 8 right?

 

[steve]

If you ground pin 2 of the FP Relay and the pump turns on then for some reason the ECU isn't grounding it.

There could be an issue with the wiring from the ECU, the transistor in the ECU failed, or the ECU isn't seeing cam pulses telling it to turn the pump on.

If you have DSMLink you can test the transistor output by tell it to turn the pump on.

 

[Dihtung Glava]

Figured it out.

I traced the white/red wire from pin 2 on the fuel pump relay back to the ECU to test continuity and noticed it wasn't going to pin 8 on the ECU but rather to pin 22, so one across and to the left of where it should be. In it's place was the green AC compressor wire. I switched them around and the pump works now.

Thanks for the help!