Fuel Gauge

[Ricko1966]

I don’t think the sending unit is the ground, there should be a ground wire that runs from the sending unit to the frame. The tank just sitting in the saddles would be a terrible body ground. It actually sites on rubber or tar paper in there from the factory to prevent squeaks.

If it is bouncing from full to zero constantly, sounds like a ground wire problem. You could try to run a ground wire from the frame to one of the flaps of pressed welded tin on the tank with a self-tapper and see if it fixes it.

The electricity passes through the sending unit to ground,the sending unit varies the ground,to change the gauge reading,so technically you are right there is a ground wire running from the sending unit to ground. But the gauge ground is the sending unit. Just like the oil pressure gauge ground is the oil pressure sender,even though the sender grounds to the block.

 

[Coffee Roaster]

I don’t think the sending unit is the ground, there should be a ground wire that runs from the sending unit to the frame. The tank just sitting in the saddles would be a terrible body ground. It actually sites on rubber or tar paper in there from the factory to prevent squeaks.

If it is bouncing from full to zero constantly, sounds like a ground wire problem. You could try to run a ground wire from the frame to one of the flaps of pressed welded tin on the tank with a self-tapper and see if it fixes it. Of course if there is a lot of corrosion around the sending unit where it meets the tank, this won’t work, but it’s easier than pulling the bed off as a first step and the sending unit is under the cab anyway, not the bed so the way to do it is drop the tank.

thank you I will try the ground wire first

 

[Old Guy Bill]

These trucks can be very bad about corrosion, you might want to look at every grounding point, tanks, cab, bed, etc...

 

[DRW65]

If the gauge needle is swinging all over the place when fuel level is below full, it will most likely be the resistor on the back of the gauge, I had the same problem. New gauge from LMC solved the issue, I do not know if the resistor can be sourced by itself.

 

[legopnuematic]

Just to save you time and frustration, if you end up needing access to the sending unit, removing or lifting the bed won’t really work. The sender is basically in the middle of the cab and bed gap.

Dropping the tank is the right way to do it.