Fuel Level Indicator Calibration Test (1968-74)

When instrument voltage regulator or gauge is suspected of being out of calibration, having a fluctuating movement, or a high or low reading, both the gauge and IVR must be tested simultaneously. This test is done on vehicle.

Test equipment consists of a suitable fuel system tester (WRE-500-70) if available, or a pair of 10 and 73 ohm resistors, or another fuel sender of known good quality.

If test is performed with resistors: Disconnect wiring connector at sender unit, connect the resistor between the gauge lead and a suitable ground. Turn ignition on. With the 10 ohm resistor, the gauge should read on or above FULL. With the 73 ohm resistor, the gauge should read on or below EMPTY.

If test is performed with a good fuel sender: Disconnect wiring connector from sender and connect it to substitute sender, be sure sender is grounded. Turn ignition on, move float rod against full stop position (away from fuel filter). The gauge should read on or above FULL mark. With float against empty stop, gauge should read on or below EMPTY mark.

If gauge performs as indicated, replace sender unit. If gauge does not perform as indicated, replace IVR and retest to determine if gauge is causing trouble. If gauge now (with new IVR) reads correctly, problem is solved. If gauge is still out of calibration, gauge is defective and must be replaced.