Fuel guage

[Sonarman]

My fuel guage works fairly good but when I put the headlight switch to on it pegs full. Do you think I have a ground problem? Guage shows 3/4 when the tank of full. I can live with that.
Thanks in advance.

[rmel]

The Fuel gauge is basically an Ammeter, the more current the higher the reading.
The fuel sender is a variable resistor, Full is approximately 10 Ohms, Empty about 180 Ohms.
So first off, if your reading 3/4 when full check your ground connections. The ground at the
top of the tank is typically a weak spot. The 4 screws at the top of Fuel sender can loose
compression as the cork seal shrinks thus creating a poor contact and higher resistance
resulting in lower meter readings.

[norcal pinz]

yes the fuel guage pegging when the lights are turned on is a bad ground i was having this issue too.

[jan.bauwmans]

And how did you fix the bad ground ? I tried a ground wire directly from the sender to the gauge but doesn't work. When I connect the ground wire that comes from the speedo it shows more or lesse correct reading but when i turn on the headlight the meter shows more fuel in the tank....

Verstuurd vanaf mijn SM-G998B met Tapatalk

[rmel]

A solid chassis ground is needed both at the sender and Gauge for this type
of VDO gauge to work properly. Starting with the Sender, you should ground
that directly to the chassis right at the tank and not run an independent
ground lead. Use some Scotch-brite or steel wool to clean under the 5 screw heads.
I have on occasion place a "star" washer on these to ensure a better connection.

Back at the Gauge make sure there is a very good and direct connection to
ground for the meter. These gauges are dual-coil and insensitive to Battery voltage.
I have attached a short Tech article on how these work and they are indeed far more
sensitive to a poor Ground than applied Voltage.

Balance coil guage.pdf

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