Thread: How to install a Fuel sending unit?????????

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Bad grounds are the number one cause of electrical problems - especially in after market applications. Dirty or loose grounds induce a high impedance (or worse, open) condition that does not allow the circuit to be completed.

I am assuming that we're dealing with a contemporary 12 volt negative ground system. Most fuel senders have a lug that's electrothermically welded to the frame of the sender. Sometimes there's a wire attached from the supplier but in any case, the frame of the sender must be bonded to the frame of your car. Make sure that the connection is clean to bare metal and nice and tight. The sender acts as a variable resistor as the fuel level changes, the resistance changes and the gauge reports the level based on the reading through the sender to ground (the frame of the car)

The ground needs to be at the sender as the gasket between the sender and the tank may prevent the sender from coming into good tight (electronically equal potential) contact with the tank.