Author Topic: Fuel pump and selector valve wiring  (Read 703 times)

Offline TateBallard

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Fuel pump and selector valve wiring
« on: September 19, 2021, 11:33:37 AM »
My dad has a 1987 Chevy Silverado 1500 that is his version of a perfect truck. About a year ago I tried to get it running, both the fuel pumps were shot in it. I hastily cut the wires running off the frame rail that tees off into both of the fuel pumping wiring and the fuel selector valve wiring. I need some help with figuring out what to wire where. I have a tan/white, pink, gray, and tan wires running off the frame rail. Each tank has purple, gray, and black wires. The selector valve has a pink, tan, green, pink/black, and pink/white. Any help would be appreciated!

Offline 75gmck25

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  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: Fuel pump and selector valve wiring
« Reply #1 on: September 19, 2021, 12:04:23 PM »
Try looking through the wiring diagrams they have posted on this site.   https://www.gmsquarebody.com/threads/1973-1991-wiring-manuals.14498/

Offline bd

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Re: Fuel pump and selector valve wiring
« Reply #2 on: September 19, 2021, 02:45:14 PM »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline TateBallard

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Re: Fuel pump and selector valve wiring
« Reply #3 on: September 22, 2021, 04:25:22 PM »
Thanks! One question though, where does my Tan/white off the frame rail run to?

Offline bd

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Re: Fuel pump and selector valve wiring
« Reply #4 on: September 22, 2021, 09:16:04 PM »
Tan/Wht is Ckt 120 from the fuel pump relay.  In a single tank application, Tan/Wht would connect directly to the in-tank fuel pump.  However, on a dual-tank application, Tan/Wht plugs into Ckt 120 (Tan/Blk) through a single wire connector and routes back up into the cab to the fuel tank selector switch.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline TateBallard

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Re: Fuel pump and selector valve wiring
« Reply #5 on: September 23, 2021, 09:43:11 AM »
Where is the tank/black wire?

Offline 75gmck25

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  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: Fuel pump and selector valve wiring
« Reply #6 on: September 25, 2021, 05:26:38 PM »
I assume that on later trucks they used the same ground as in my '75.    There is a ground terminal on the sending unit body and the black wire is crimped to that terminal.  The black wire then runs from there down to the outside of the frame rail, through a hole from the outside to the inside, and is then grounded to a bolt screwed into the frame.