Fuel gauge full

[Chrisblundell]

Hi all hope, everyone is having a great spring so far...and avoiding the pollen if its in your area...still all over in NJ here..

I saw a few threads on fuel gauges being stuck at full..but I see that everyone's situation is a little different.

I have:

-Stock replacement tank for 302 from tom's I believe, new sending unit as well.
-All new wiring we put in from scratch, painless harness.
-Original cluster
-Additional electric fuel pump, cheap edelbrock one from autozone
-One tank, followed instructions to close off aux tank so that I would get a reading

Gauge was working perfect at first, no issues whatsoever. Just recently, it stays at full whenever key is in ACC and/or running. Not shot my tank is actually full either

Took the pigtail off of the sending unit today, and turned the key into ACC. Needle didnt move, stayed at empty. Popped it back on, same thing, stuck at full. I've been reading on here that these new sending units go bad? Is that really the case?

 

[ared77]

Yes, they do.

As a simple test on an old Ford Bronco, Mustang, etc you can ground the connector at gauge to chassis and w key on you should see the gauge show "full". If it does you have proved your gauge and wiring are ok. In your case, if the tank isn't full, and yet when you connect the pigtail to gauge you show full...just as if you grounded the pigtail. That makes me think your sender has shorted out.

 

[serial car restorer]

That makes me think your gauge has shorted out.

I am thinking the opposite, that the sending unit is shorted to ground.

 

[Broncobowsher]

What do the oil and temp gauges do? do they work normal? Not hooked up? Pegged as well?

The nice part about a gauge pegged full, providing it is just the fuel gauge that is the problem, disconnect the signal wire at various places. If the gauge stays pegged, keep working toward the gauge. If the gauge drops, start working toward the sending unit.

 

[ared77]

SCR that's what I meant, I just typed it wrong. I went back and corrected it.