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Matt Carey
Matt Carey, Chevy Technician
Category: Chevy
Satisfied Customers: 258
Experience:  6yrs experience, and access to factory service information
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97 chevy S10: my fuel tank..sending unit..gas gauge..fuel pressure

Customer Question

I pulled my fuel tank on a 97 chevy S10 and removed the pump/sending unit because my gas gauge wasn't working. Found the level sensor to be bad. I didn't replace anything and put everything back together and now I don't have any fuel pressure. No power is being sent to to my fuel pump. As soon as I turn the engine on, I get a short burst of voltage peaked at about 10 vdc, then it goes to zero. I can power the pump directly with 12 v so the pump works. I tried applying 12v to the red test lead in the engine compartment and I get nothing. I can not tell if the pressure switch is the culprit. It is getting 5 volts, but that is all I know. I could use a schematic of the circuit to help.
Submitted: 4 years ago.
Category: Chevy
Expert:  Matt Carey replied 4 years ago.

Hi this is MATT. The pressure sensor should not affect the fuel pump operation. You say you can power the pump directly, so that means that your ground is good. But you should be able to power it from the red prime connector. I'll include a diagram, but the prime conn. goes to the fuel pump relay and then to the pump. So try to power the pump from the relay. Then you will have to check the signal from the PCM to the fuel relay. It sounds like everything is working for a few, but then what? Do you loose the PCM to relay power (to close the relay)? let me know, MATT

 

graphic

Customer: replied 4 years ago.
I can power the pump directly, but i am supplying my own ground also. I'll check to see if I can power it up with it's own ground. Also, is the pump relay in the glove box? There are 3 relays there, but no indication as to what they are for.
Expert:  Matt Carey replied 4 years ago.

Use the wire colors to identify the relay. dark green/ white, blk/wht, org, red, and grey. The diagram should help, With the relay removed, you should have a ground on the grey wire. This will prove that the pump is grounded. MATT

Customer: replied 4 years ago.
no ground on the grey.
Expert:  Matt Carey replied 4 years ago.

Okay, check the black wire coming from the fuel pump at the tank for a ground. MATT

 

It should bolt to an eyelet at the crossmember.



Edited by Matt Carey on 8/21/2010 at 9:44 PM EST
Matt Carey, Chevy Technician
Category: Chevy
Satisfied Customers: 258
Experience: 6yrs experience, and access to factory service information
Matt Carey and 3 other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
OK, Thats it, now its working, put new eyelet on it..corroded. Thanks!
Expert:  Matt Carey replied 4 years ago.
Great, glad you found it. Have a good weekend! MATT

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Matt Carey
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