Fuel pump voltage

[JustDSM]

I've gone through some tests to find out why my '93 Ty wasn't starting and narrowed it down to the fuel pump.

Anyhow.. On a whim I decided to check the voltage that the pump was recieving when the ign. was turned to the "on" position. With the battery sitting at 12.10v I got 8.7something volts at the fuel pump harness plug back at the tank. Doesn't seem normal to me. Any thoughts on why there was a voltage drop of almost 4v?

It has crossed my mind to wire a the pump directly to the battery through a SPDT relay.

Anyone have a schematic of the fuel pump circuit they could post up?

 

[Christian Dionne]

Re: Fuel pump voltage

Driver side relay, it has a tan wire I think...might be old and have corrosion. Use the bypass terminal to turn on the pump and get out your voltmeter. Doubt it's the wire. What are you using for your ground when you check the voltage? Sometimes the ground terminal doesn't make good connection on the frame.

 

[JustDSM]

Re: Fuel pump voltage

I'll check that tan wire out on the fuel pump relay. I'm assuming thats what you were referring too.. I'll also jumper 12v to the test connector and see what I've got back there.

When I was checking ground i was using the the factory ground location (the screw). But if you say it's problematic, that might be the issue right there. I'll scrub it clean and make sure its got some dielectric grease covering it to help prevent future corrosion. Thanks for that tip!