Fuel pump not getting power

MIKEH8068

MEMBER
1988 CHEVROLET 1500
5.7L
V8
4WD
AUTOMATIC
200,000 MILES

My truck listed above K1500 model, was running, and shut off. You could hear the old pump kick on and run but wouldn't start the truck. Replaced the fuel pump and sending unit as well as the relay unit but still has no power to the fuel pump. I hooked up two wires to the battery and ran to the fuel pump. It started working but wouldn't start the truck. In line fuse doesn't have power to it. One wire on the relay shows electricity using a test light. Any suggestions need my truck running soon. Thanks in advance.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

We need to start with getting on the same page as to what voltage you are finding at the pump.

So, I am attaching the wiring diagram below but let's start with checking the voltage at the pump when cranking the engine or the key is on and see what we have. Basically, we need to have 12 volts so anything else we need to track down.

https://www.2carpros.com/articles/how-to-check-wiring

Next, we need to track the power through the system and find where we are losing it. However, if we have low voltage then we need to find the likely wiring or connection issue that is causing the resistance or loss of voltage.

Let's start with this and go from there.

Thanks

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Fuel pump not getting power

1 Reply

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