Quote:
Originally Posted by Roger V
In his case, another strange thing is he says, if he took every tank mounting bolt out, it reads correctly. With just one even started, it returns to reading wrong! This would seem to be just the opposite relative to grounding.
|
This comment reminded me of something possibly similar.
At night have you ever noticed an older car with 4 headlights, with one headlamp on and the other 3 are glowing orange? It took me a while to figure that out. It's caused by a bad/missing ground for the headlamp bulbs on the 'both orange' side of the car. The power to the one headlamp on that side has to travel thru the common filament connections of 3 bulbs to get to a good ground, behind the one bulb that's working correctly.
Check for a good clean connections on the ground cable from the body/firewall to the engine block and negative battery cable.
The positive battery cable is connected to the starter solenoid, then thru other wires to the fuses, switches and various accessories. The negative battery cable usually bolts to the engine block because that's the shortest ground path for the (high current) starter motor.
In order for any body mounted electrical accessory, gauge or light to function, each of those items has to have a good connection to the body and the body has to have a good connection to the engine block and/or negative battery cable.
It's possible that the reason the fuel gauge goes up, or reads incorrectly, when the sender is grounded is because some other voltage source (another dash gauge?) is using it to find a path to ground.
.