87 R10 Fuel switch wiring

[ksimstx]

I have an 87 R10, dual tanks. small block carbeurated motor, so no TBI. My dual tanks selector switch isn't working. I have ground continuity on the black wire. Can someone tell me where the tan/white wire should go, and I suppose the tan, and gray wires go to the fuel valve switch? My passenger side tank works, but the drivers side tank does nothing, and when you flip the tank selector switch, you don't hear the fuel valve under the frame doing anything. Thanks for any help. Don't want to just throw parts at it. I think I have something electrical going on.

 

[75gmck25]

The tan/white and tan wires are the wires to the sending units. They change the gauge feed, but don’t affect fuel flow.

How long have you had this truck? If you have a carbureted engine, but in an ‘87 R10, it would have originally been a TBI. It’s hard to say what they did with wiring. The original fuel pumps would have been in-tank and the dash switch also switched the pumps.

 

[shinkle]

I'm trying to get phsyched up to tackle my passenger tank not working. Here is a diagram that may help.

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[ksimstx]

Is the tan/white wire going to the fuel selector valve supposed to be 12V, and what polarity should the tan, and grey wires be that go to each sending unit? I cant seem to get the gear inside the valve to operate/move, I think that is my problem. I have checked continuity from all wires coming from the dash switch to the fuel valve and they are good, the wires from the fuel valve to each sending unit are good also. I'm thinking I have an electrical issue, but am a bit perplexed.

 

[mtbadbob]

Is the tan/white wire going to the fuel selector valve supposed to be 12V, and what polarity should the tan, and grey wires be that go to each sending unit? I cant seem to get the gear inside the valve to operate/move, I think that is my problem. I have checked continuity from all wires coming from the dash switch to the fuel valve and they are good, the wires from the fuel valve to each sending unit are good also. I'm thinking I have an electrical issue, but am a bit perplexed.

Do you have the correct dash switch? They are different from carb & TBI