Help with dual tank wiring

[wjjeeper]

I have searched and cant find an answer

Truck is a 77. All tanks senders, wiring, switch etc is new.
I have gone through the wiring diagram and verified all connections are good. Verified the grounds for the senders are good.

The truck will run off either tank amd I can hear the solenoid switch from each tank. But the gauge will not register any fuel level when on the right hand tank.

Any ideas? How can I verify sending unit is bad?

[Kudzupatch]

Woops, I should read closer!

[ray_mcavoy]

You can use a multimeter to check the sending unit(s). Set the meter to the resistance scale and connect one of the meter's leads to the sending unit's ground wire. Unplug the sending unit and connect the meter's other lead to the terminal on the sending unit. The mulitmeter should read somewhere between zero ohms (if the tank is empty) up to about 90 ohms (if the tank is full).

If the meter shows zero ohms and you know the tank is not empty, the sending unit is either shorted out, has a sunken float, or is stuck in the empty position. In this case, the fuel gauge would indicate empty.

If the meter shows considerably higher than 90 ohms (like an infinite reading), the sending unit is open circuited (probably a broken wire inside). When this happens the fuel gauge will peg beyond full.

[wjjeeper]

^^^thank you!