You can test out the sender to see if it's the sender or the guage.
1. Remove gauge. Ground Y/W wire of fuel gauge sender located at bottom of gauge. Turn ignition switch ON.
Fuel gauge must indicate FULL. If gauge indicated FULL, gauge is functioning correctly. Proceed to step 2.
If gauge did not indicate FULL, proceed to step 3.
2. Set MULTI-METER (Part No. HD-35500) to RXI scale to measure the resistance of the sending unit. Place one probe on Y/W and the other probe on a good ground.
a. If fuel tank is full, the reading should be 40 ohms. An empty tank should have a 240 ohm resistance. A half full tank will be approximately 97-118 ohms.
b. If a very high resistance or infinity is indicated on the meter, the sender may be “open” or not grounded.
Check that sender and fuel tank are grounded by placing one probe of Multi-Meter on sender flange and the other probe on crankcase. Meter must indicate one ohm or less. Replace sender if one ohm or less was present. If a higher resistance is present, check for poor connection on ground wire.
3. Check voltage to O/W (+) and BK (-) wire of fuel gauge connector [117] if gauge did not indicate FULL.
a. Correct reading is equivalent to battery voltage.
b. If battery voltage is not present check for broken or disconnected wire. Replace gauge if wiring problem is not found.
