Fuel Gauge on "E" and bounces when braking/signaling

[clay1937]

Hello,

I just picked up a 1971 Blazer, and the fuel gauge doesn't work...it sits on "E" (empty) all of the time, unless you press the brake, at which point the gauge jumps to "F" (full), until the brake is released, at which point, the guage returns to "E".

This same behavior is seen when signalling to turn right...every time the signal flashes, the gauged jumps to "F" and back to "E". For some reason though, it doesn't do this when signaling to turn left.

Is this just a grounding issue or a fuel sending unit issue?

Thanks!

 

[Greg72]

A broken ground wire will cause the gauge to peg itself on the "F" side... so if the gauge is constantly on "E", it sounds like the opposite problem.

The gauge reads from 0 to 90 ohms (0 Ohms is Empty, 90 ohms is Full) obviously a broken ground wire signals infinite resistance which is why the gauge pegs to "F". In your case, it sounds like the circuit is shorted somehow....I'd suspect the sending unit is bad in your truck.