Fuel gauge reading

[bowtiemanchevyman]

0

Originally Posted by AGearHead4Life

Isn't there a ground on top of the tank where you install the sending unit?

My guess would be that ground, the gauge or the sending unit. Knowing what ohm the sending unit should read would help to trouble shoot this. Anybody have this spec? Without this information, you could temporarily swap another gauge cluster to eliminate the gauge from the list.

Odds seem to be in favor of it being the sending unit. If determined its the sending unit, you may even be able to clean it up or adjust it. LMC is probably a dependable source for a new sending unit.

they are 0-90 o= full and 90 is empty

[hatzie]

Originally Posted by AGearHead4Life

Isn't there a ground on top of the tank where you install the sending unit?

My guess would be that ground, the gauge or the sending unit. Knowing what ohm the sending unit should read would help to trouble shoot this. Anybody have this spec? Without this information, you could temporarily swap another gauge cluster to eliminate the gauge from the list.

Odds seem to be in favor of it being the sending unit. If determined its the sending unit, you may even be able to clean it up or adjust it. LMC is probably a dependable source for a new sending unit.

Full is 88-92 ohms.
Empty is 0 ohms.
3 O'Clock usually indicates an open circuit between the sender and the gauge. This is only true when the gauge remains pegged at 3:00 regardless of fuel level.

Since the gauge is sweeping 1/4-3:00. The sender circuit has increased resistance, the 30 year old gauge calibration resistor has loose or corroded connections, or the sender has started to fail.
Sources of increased resistance are damaged wiring between the frame ground and the gauge, loose spring contacts in the cluster housing, corrosion on the printed circuit to cluster plug.
I'd look at the tank to frame ground first... Clean up a spot on the tank pinch weld with sandpaper then run a temporary jumper to a clean spot on the frame.
The gauge can be tested by grounding the sender pin on the cluster and turning on the ignition. It should read Empty with a dead shorted sender wire. If it reads 1/4 the gauge or calibration resistor are the problem. Carefully clean up the resistor and nut contact surfaces with 000 steel wool and re-install. If the printed contact surface of the resistor is worn through to the ceramic you can put some slightly larger washers under the nuts to move contact to the undamaged portion of the resistor.

[RPOZ11]

NICE description!