gas gauge

[cape square body]

I'm need help with fuel gauge issue it works on drivers side tank and not the other
the previous owner replaced tank and sender it reads right on full not passed full
on the one not working . my question is does that sending unit get power from the tank selector
valve so when I switch to passenger tank there should be 12 volts to sender?

 

[AuroraGirl]

I'm need help with fuel gauge issue it works on drivers side tank and not the other
the previous owner replaced tank and sender it reads right on full not passed full
on the one not working . my question is does that sending unit get power from the tank selector
valve so when I switch to passenger tank there should be 12 volts to sender?

it takes a ground. the sender needs to be grounded to the truck frame, and the wire from the sender that goes to the switch yes

I would say if you never had the tank down maybe its time to bring down and then play with the arm, the thing may just be froze

 

[75gmck25]

As AuroraGirl said, make sure the sending units are grounded. Unscrew the bolt, sand down the frame to bright metal, and screw back in. Also follow the wire up and make sure it’s still connected to the sending unit.

An 87 uses a solenoid with 6 terminals, so you will have to determine which one is which, and where 12 volts is applied. I think that newer solenoids also stay in each position (left or right) even when you turn off the ignition.

The old single-terminal solenoids were simpler because they defaulted (with no power) to the main tank, and when 12 volts was applied they switched to the aux tank.