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Tom Richards
Tom Richards, ASE Certified Technician
Category: GM
Satisfied Customers: 52
Experience:  Owner of MasterTech Auto in Washington State. An ASE Certified Master Technician for more than 30 years.
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Wireing diagram of the fuel pump curcuit on a 1999 chevy express van

Customer Question

wireing diagram of the fuel pump curcuit on a 1999 chevy express van
Submitted: 5 years ago.
Category: GM
Expert:  Tom Richards replied 5 years ago.

Tom Richards :

Welcome, Which engine do you have in this unit?

Customer:

5.7

Tom Richards :

Cool, that's what I thought. hang on.

Tom Richards :

Full Size Image

Tom Richards :

Here's the main part.

Tom Richards :

ECM fuse B runs it.

Tom Richards :

Red prime connector is nice on these cause you can test it from there. Or at the relay.

Customer:

would i be assuming right that in the diagram that c301 is a connector and s101,s152 and g103 are splices befor ground

Tom Richards :

Yes, C301 is going to be near the fuel pump.

Customer:

on the black wire from the pump to ground

Tom Richards :

Yes, black is ground. Look for voltage on that with the pump on, there should be no more than .5. I like to jump the pump at the relay and just leave it on for testing. (30-87 pins)

Tom Richards :

From what I read, running a new ground or repairing the old one at the frame will do it.

Tom Richards :

Interesting, G103 on this unit is on R. cyl. head, rear.

Customer:

ok it looks im im going to have to trace down the connections on the black on its way to ground. one more question if its extra thats fine, dose the pump run continuiously while the engine is running or is there a pressure sensor that cuts it on and off according to the pressure or dose the pressure valve just send the fule back to the tank?

Tom Richards :

No, this older style runs all the time, no duty cycle, just a physical regulator. You can run a new ground to the frame, you will get the same result. Just make sure it's clean, and use dialectric grease to seal. it.

Customer:

yes i found the ground lug on the right rear head. thanks a lot. ill be saving this to reconnect with you on any problems in the future.

Customer:

this is the first time i have tried just answer. you saved me a lot of time. thanks again.

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