Fuel Pump issue...yet another

[grnchevyz]

Ok,

EVO3 upgrade all done, FMIC all done, Injectors all done, walbro 190 done.

Problem:

Fuel pump not turning on.

What's been checked:

Traced all wiring from fuse box to relays, relays to ecu, relays to fuel pump. No breaks found wires are all continuous.

Put 12v on test port of Fuel Pump, fuel pump turns on.

Tested MPI and fuel pump relays. Relays are good.

The white/red wire on the fuel pump relay harness (the one that goes to pin 8 on the ECU) is NOT throwing a ground on ignition.

Bad ECU?

I'll swap with a 95 EPROM ecu and see...anything else I missed?

Thanks in advance!

 

[grnchevyz]

UPDATE:

95 EPROM ECU, same thing, no ground thrown on Pin 8 - Fuel Pump Relay

Also changed the Throttle Body from a previous issue...would that have anything to do with it?

How about the CAS? Although I think the CAS is only for start and does not control the fuel pump relay.

 

[grnchevyz]

Got it!!

CAS wasn't sitting properly.

SO, just for other people in the future, the CAS is what tells the ECU to throw a ground on Pin-8 for the FUel Pump Relay.

Car is running now

All happy!

 

[Spooling99]

Good to hear you got it running. I had starting problems for a while turned out to be a coolant temp sensor.

 

[Kevin Jewer]

The temp sensor will make the car run super rich, since it defaults to -40F, but it won't stop the ECU from engaging the pump, as Lou was seeing. Without the CAS signal the ECU won't trigger the injectors, coils, or pump. Two totally unrelated problems