73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: NTDYNA on June 06, 2021, 10:02:28 am
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I bought a fv5k kit for my C10, I'm going to retain the factory dash switch though. The instructions aren't that clear, Do I need to splice into the sending unit wiring with the valve, then just wire the solenoid, gauge wire directly to the new valve?
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What year is your C10 and what style tank selector do you currently have.
The valve you have looks like a standard pig tail and connector for an '87 TBI dual tank truck. Studying the wiring diagram may help you figure out which wires are which.
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What year is your C10 and what style tank selector do you currently have.
The valve you have looks like a standard pig tail and connector for an '87 TBI dual tank truck. Studying the wiring diagram may help you figure out which wires are which.
I have a 76, but the tank selector that came on this truck was wrong. It was a 3 valve for say a non return system.
I think I've figured out where most of the wires go to, but the new pigtail has 5 wires and my set up only has 4 going from the OEM switch to the selection valve itself.
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This forum has wiring diagrams and a maintenance manual.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=11766.0
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http://forum.73-87chevytrucks.com/smforum/index.php?topic=9072.0
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Thanks guys, I appreciate it
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OK so, I plumbed it all, the wiring is where I'm having issues really. I have 4 wires (LH sender, RH Sender, gauge and solenoid)
The new valve has 5 wires, I bought the kit version of this tank solenoid but I'm trying to use my OEM button in the dash.
I have not a clue where to put my solenoid wire from my switch!
Any and all help would be great, dump it down because I hate wiring as it is. (https://uploads.tapatalk-cdn.com/20210612/8efd0df6a0eee23cc0f3c31bfa381d58.jpg)(https://uploads.tapatalk-cdn.com/20210612/e47e7a1e45cb4b78651899fd18b19236.jpg)(https://uploads.tapatalk-cdn.com/20210612/c4daf46ba40ce9b3b88c311bc5d94098.jpg)(https://uploads.tapatalk-cdn.com/20210612/89962858e7f9a3c3da2cefbc5e301650.jpg)
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Do you have a '76 C10 with factory dual tanks? How many terminals on the back of the dash switch?
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Do you have a '76 C10 with factory dual tanks? How many terminals on the back of the dash switch?
Yes I do, 5 are on the back of my factory switch
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The motorized valve requires a DPDT switch. The OEM factory switch in the dash is a hybrid DP(S/D)T configuration. To make the valve work you will need to insert a SPDT ISO relay not shown on the diagram that came with the valve. The SPDT relay will be controlled by the side of the switch that has only two terminals.
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The motorized valve requires a DPDT switch. The OEM factory switch in the dash is a hybrid DP(S/D)T configuration. To make the valve work you will need to insert a SPDT ISO relay not shown on the diagram that came with the valve. The SPDT relay will be controlled by the side of the switch that has only two terminals.
So I need the 81-87 switch and do you by chance have the part number for this relay?
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If you are willing to replace the dash switch, use the 1987-up rocker switch for TBI and dispense with a relay. I suggest the TBI rocker switch because it is not a momentary contact, so you don't need to hold it down if the valve rack is sluggish. A plus is that the diagram that you received with the new valve applies directly to the later model switch.
You may find it beneficial to peruse the topics, Dual Tanks Theory of operation (http://forum.73-87chevytrucks.com/smforum/index.php?topic=37007.msg310661#msg310661) and Fuel selector switch (http://forum.73-87chevytrucks.com/smforum/index.php?topic=23517.msg197000#msg197000).
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If you are willing to replace the dash switch, use the 1987-up rocker switch for TBI and dispense with a relay. I suggest the TBI rocker switch because it is not a momentary contact, so you don't need to hold it down if the valve rack is sluggish. A plus is that the diagram that you received with the new valve applies directly to the later model switch.
You may find it beneficial to peruse the topics, Dual Tanks Theory of operation (http://forum.73-87chevytrucks.com/smforum/index.php?topic=37007.msg310661#msg310661) and Fuel selector switch (http://forum.73-87chevytrucks.com/smforum/index.php?topic=23517.msg197000#msg197000).
So 87 switch and basically wire is directly like the universal switch that came with the kit?
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Yes, with a caveat. The TBI switch has only 4-terminals because it is internally wired with the cross X.
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Yes, with a caveat. The TBI switch has only 4-terminals because it is internally wired with the cross X.
So how do you wire those 4 then?
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The external wiring connects exactly as shown on your diagram.
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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?
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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.
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No I switched it to the 87 style switch and tank solenoid. I wired it like this(https://uploads.tapatalk-cdn.com/20210902/50b4e41e0f2bfeaf9f20a554817ed674.jpg)
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