Providing necessary power supply to fuel pump
 

Short story....
89 c1500 5.7, removed factory tbi and olan to remove factory wiring to ecm.

Plan is to
1. Ground relay to fuel pump to provide power
2. Use factory oil pressure switch to provide ground

Currently, truck is being reassembled with a fitech unit, i would like to have the oil pressure switch work as it does for the ecm...

Does anyone know if the ground to relay can be routed through this switch and work as it did the way factory designed ?

Re: Providing necessary power supply to fuel pump
 

89, hmm. Do you have the oil pressure switch behind the distributor?
You should be able to use that, it was designed to work when oil pressure was over 4 psi to keep the fuel pump working. I think it the white and orange wire.

I think 89 had a sensor above the oil filter as well, that goes to the gauge but on some the pressure was the 3rd wire one the other sensor. Maybe that was 90 or 91?

Re: Providing necessary power supply to fuel pump
 

it has both, i hope the switch is just that, a pass through the ecm to trigger the fuel pump and MEL.

i plan to wire through it, pressure grounds and sends signal to pump...no pressure, truck dies.

Re: Providing necessary power supply to fuel pump
 

The wire from the oil pressure switch runs to the relay, it should trip the relay to kick on the fuel pump once oil pressure range is achieved.
If you run a jumper on the oil pressure switch plug at what i think was the orange an white wire, that should trigger the fuel pump relay.

Re: Providing necessary power supply to fuel pump
 

I think were on the same page...i plan to wire the following
Starting
Charging
Few gauges

Just to start and run the motor, the fitech of course has its wiring.

Then i plan to use some of the gm fail safe...oil pressure switch.

End goal is remove all factory wiring and ecm...

Trans will get the vaccum conversion, and i will need to figure out killing the ac comp at wot.