Fuel gauges irratic

[DickG]

During my latest flight both fuel gauges (Vans analog) would fluctuate from reading normal to reading high, then returned to normal simultaneously. This happened several times. The fuel pressure gauge would also increase above normal. The fuel pressure gauge read 5 psi after the engine was shutdown.

Fuel flow was normal. Voltage was normal and didn't fluctuate. Engine ran normally.

Any thoughts? I'll be diving under the instrument panel to look for loose wires or unusual conditions.

[johngoodman]

Dick,
I don't know what kind of EIS you have, and I'm no expert, anyway. But, I would suspect that there is a resistor somewhere that modifies the power going to the floats. Since it all happens at the same time, perhaps you spliced one resistor going to multiple devices....
John

[airguy]

Sounds like a grounding issue.

[jimbo]

I have the standard Vans float sender as well feeding my GRT EIS.
I have found the same fluctuating readings primarily
In a turn which will give a high or low reading. But
It takes a long while to read back to the right volume after
I level the wings. With only 12 hours in Phase 1
I don't know if this is a normal characteristic with
Vans senders. I always keep mental track of what my
Fuel volume should be based on flight time as I have
Low confidence in the fuel Gage's at this point.

Will be interested in knowing what others are experiencing

Jim
RV9a
N512JM

[DickG]

Took 30 seconds to find a loose nut on the ground wire post of the fuel pressure gauge. The same post also had the ground wires for both analog fuel gauges.

All three instruments function normally again.