Diagnostic Aids

Verify that the fuel level is in the same range as the customer concern.
For intermittent diagnosis, refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .
Use the fuel level sensor resistance to verify the fuel level sensor operation. When the fuel tank is empty, the fuel level sensor resistance is approximately 0 ohms. When the fuel tank is full the fuel level sensor resistance is approximately 90 ohms.

Fig 1: Fuel Gage Inaccurate Or Inoperative (Single Tank L65 Diesel Engine) (1 Of 2)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Fuel Gage Inaccurate Or Inoperative (Single Tank L65 Diesel Engine) (2 Of 2)

Courtesy of GENERAL MOTORS CORP.