Per ➥ Basic Engine Gauge Theory and Testing
Testing Fuel Guages:
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 (½ 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.
4. Disconnect Pink Wire from Sender on Engine
5. Test continuity of Pink Wire.
Zero Ohms from Block End to Gauge End - If not, repair or replace Wire.
6. Measure Resistance from Sender Terminal (on Block) to Ground on Block.
Should read as per (3) above - If not, replace Sender.