Need help with fuel guage please!

-----Original Message-----
From: Michelle ]
Posted At: Wednesday, March 01, 2006 5:52 AM
Posted To: rec.aviation.owning
Conversation: Need help with fuel guage please!
Subject: Need help with fuel guage please!

Dave wrote:
OK...a 1976 PA 28 151..

After a few minutes of running, the port guage will start to fall
towards E.

It is showing 3/4 now (fuel at tabs), and will sag to 1/4 within
about 15 min, while I am operating on the starboard (other) tank.

Shut down for a few hours, guage resumes normal (correct)
indication.

We have checked / replaced, tank grounds, sender, wiring to guage.

I think the guage terminals handle 12 V to the left terminal
(looking at it from under the panel) (starboard terminal) , The
other
to the tank sender (port terminal).. (grounding this terminal when
the fault is present will cause a "full" indication).

From what I recall, there is a "ground" connection internal in the
guage. Anybody know how this is grounded?

I suspect a bad connection here somewhere..

Driving me up the wall..of course every time I attack the problem,
meter in hand, it works fine.

Anybody any ideas? Suggestions or test procedures?

Dave
Sounds like the float is filling up or becoming saturated......
Michelle
[Jim Carter] Wouldn't that tend to move from reliable to unreliable and
then stay there or get worse? Why would shutting down tend to reset
everything if it was a float? I has to be something that is
deteriorating electrically over a period of time while the power is
applied. Then when power is removed the charges bleed down and return to
normal until the next time power is applied. I don't know the circuit
but it sure sounds like there is a capacitor somewhere that is applying
a charge to the circuit until the power is removed and the bleed
resistor does its job.