Author Topic: Wiring up new style dual tank valve  (Read 3500 times)

Offline bd

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Re: Wiring up new style dual tank valve
« Reply #15 on: June 14, 2021, 12:33:35 PM »
The external wiring connects exactly as shown on your diagram.
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 NTDYNA

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Re: Wiring up new style dual tank valve
« Reply #16 on: September 02, 2021, 06:46:40 AM »
So I wired the truck up like the diagram but I only have a fuel gauge on one side, I have two wires for fuel gauge coming from the cluster.I only connected one. Should I had cut both and attached the two factory wires to the single wire going to the valve?
-76 Short Bed 454-

Offline 75gmck25

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  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: Wiring up new style dual tank valve
« Reply #17 on: September 02, 2021, 07:23:28 AM »
I’m confused by your description of the gauge wiring.  I assume you have the stock switch and wiring for a ‘76, where the solenoid had a single power terminal.

There should be one tan wire coming from the gauge cluster, and it runs through the firewall, down the passenger side frame rail to the tank on that side.  If you only had one tank it would just plug into the sending unit there.

The wiring for the second tank takes a very roundabout route.
When they add a second tank they install the dash switch, and run four wires over to a grommet that goes through the firewall below and to the passenger side of the brake booster.up cod ‘76
- The wiring runs down the drivers side frame rail, with one wire coming out and connecting to the tank sending unit on the drivers side. 
- The other 3 wires cross under the truck with the metal fuel lines and connect to the passenger side sending unit, the wire coming from the gauge, and the power terminal on the solenoid on the passenger side.

The DPDT switch on dash has five wires.
First half
- power from fuse box on center terminal
- power wire to solenoid on one side
- open terminal
This half of the switch determines if the solenoid has power.  With no power it defaults to the passenger side tank.
2nd half
- wire that runs to the gauge on center terminal  ( but remember the complicated routing)
- sending unit wire for left tank
-sending unit wire for right  tank
This half switches the sending unit wire from left to right tank.

Offline NTDYNA

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Re: Wiring up new style dual tank valve
« Reply #18 on: September 02, 2021, 08:45:47 AM »
No I switched it to the 87 style switch and tank solenoid. I wired it like this

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-76 Short Bed 454-