Question about 1991 Chevrolet C1500

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1991 chey pick up 1500 electric fuel pump

The wiring harness for the fuel pump has three wires to it, how many wires should show voltage when the key is in the on position

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Hello, Only 2 wires show be hot when fuel pump power is supplied. I think that the gray wire is the power side so ck that wire to ground. Also, fuel pump power is supplied from your oil pressure switch and the fuel pump relay only supplies power for a few seconds until the truck is started. Keep in mind that the fuel pump will only run a few seconds by just turning the switch on. If you want the pump to stay on without the motor running , you will have to by-pass the fuel pump relay.
I hope this will help.
CYA, gator241

Posted on Feb 06, 2009


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That does sound like a malfunction with the ignition module inside of the distributor, and you can remove the ignition module and have it tested for free at most auto part stores. If the ignition module does test out alright then the problem could still be in the pick-up coil/stator, (it can be tested using an ohm meter by dis-connecting the wire connector from the pick-up coil/stator and the ohm reading between the two wires from the pick-up coil/stator should be between 500 and 1500 ohm's, and both of the wires from the pick-up coil/stator should show an open loop or an infinite reading between each wire and ground) and if the pick-up coil/stator is found to be faulty then replace the entire distributor, or the distributor will have to be dis-assembled to install a new pick-up coil/stator.

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How do you check voltage on the fuel pump on a 2001 Chevy Silverado, was driving engine stalled but regained power drove three more miles and it quit running, I have spark but no fuel. Trying to check out...

Hello Dennis.
When you are checking fuel pump voltage on your pickup when you turn on the key the voltage is only applied to the pump for a couple of seconds unless you go to cranking position.
There are 4 wires leading to the fuel pump on your truck. The gray wire is the 12 volt positive power feed to the fuel pump and the black provides the ground. The orange and purple wires are your fuel gauge wires.
The relay for the fuel pump is in your under hood fuse panel and I believe is marked on the underside of the fuse panel cover. It should click on and off again quickly when you turn the key to "on". Having a helper to cycle the key would be handy while you put your finger on the relay and listen to it. Just because it clicks still doesn't mean it's functional but relay failure on these models is somewhat rare.
I would start by checking for power at the fuel pump harness.
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Hope this helps you out.

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