Greetings and welcome aboard the CF, J.
Basic Engine Gauge Theory and Testing ➥ https://www.cruisersforum.com/forums....html#post2597
Fuel Gauge Testing
1. Disconnect [Pink*] Sender Wire from Gauge, and turn power ON.
The Fuel Gauge should read ZERO Scale (< Empty)
2. Short the Gauge Sender Terminal to Ground.
The Gauge should read FULL Scale (> Full).
3. Measure resistance of [Pink] Sender Wire to Ground.
American Floats: 240 Ohms (Empty), 103 Ohms (Ĺ Full), & 33 Ohms (Full)
European Floats: 10 Ohms (Empty), 95 Ohms (Half), & 180 Ohms (Full)
Automotive & other Float Switches may use other resistances such as 0 - 90 Ohm, 73 - 10 Ohm, & etc.
* Pink is North American standard wire colour for fuel gauge sender wire.