2001 Harley Davidson FXSTS, I have an intermitent problem with my fuel gauge. Start with a full tank and sometimes in drops to empty or half a tank????? Thanks Mark

Check for 12 volts at the orange wire on the fuel gauge. If missing check instrument fuse and associated wiring. If present do the following checks:

1. Remove gauge. Ground Y/W wire of fuel gauge sender located at bottom of gauge. Turn ignition switch ON.

a. Fuel gauge must indicate FULL. If gauge indicated FULL, gauge is functioning correctly and go to step 2.

b. If gauge did not indicate FULL, proceed to step 3.

2. Set MULTI-METER to resistance 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 pproximately 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 ****** 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.

The fuel gauge sender is mounted internally in the fuel tank. There is a three pin connector that will have a Yellow/White wire in it (the middle wire) under the center console. This is the sender wire. Connect an ohm meter between this wire and the black wire and check for the following readings:
If fuel tank is full, the reading should be 7-14 ohms. An empty tank should have a 74-95 ohm resistance. A half full tank will be approximately 30-38 ohms.
If you ground this wire that comes from the harness, the fuel gauge should read full. If not, then fault may be in wiring or the fuel gauge itself.
Remove the front fairing to gain access to the gauge. You should have 12 volts across the orange/white and black wires. If not, check accessory fuse. If 12 volts present ground the yellow/white wire at the gauge. Gauge should read full scale. If not, gauge faulty. If gauge reads full scale, check wiring from gauge to three pin plug under tank console.

The fuel gauge sender is mounted internally in the fuel tank. There is a three pin connector that will have a Yellow/White wire in it (the middle wire) under the center console. This is the sender wire. Connect an ohm meter between this wire and the black wire and check for the following readings:
If fuel tank is full, the reading should be 7-14 ohms. An empty tank should have a 74-95 ohm resistance. A half full tank will be approximately 30-38 ohms.
If you ground this wire that comes from the harness, the fuel gauge should read full. If not, then fault may be in wiring or the fuel gauge itself.
Remove the front fairing to gain access to the gauge. You should have 12 volts across the orange/white and black wires. If not, check accessory fuse. If 12 volts present ground the yellow/white wire at the gauge. Gauge should read full scale. If not, gauge faulty. If gauge reads full scale, check wiring from gauge to three pin plug under tank console.

If your fuel gauge is showing you in accurate readings this is normal to all vehicles that are not used to fill-up gas full regularly but sometimes the cause of the inacuracy is due to faulty float valve in the gas tank you need to replace it

Sounds like a pinhole in the pick up tube inside the tank.

you probably have a bad fuel level sensor in the fuel tank.you will have to remove the fuel tank to replace the sensor.the contacts on the sensor will break causing the fuel gauge to be inacurate.you can buy the sensor without having to buy the whole fuel pump assembly.

SOUND LIKE A SENDING UNIT PROBLEM! YOU MAY NEED TO REPLACE IT AT THE TANK!

first i would check ground connections and also power, does it does it all the time? full tank or empty? if it does all the time i wouls almost suspect a fault sending unit in the tank....

sounds like a fuel sending unit problem or an issue with the sending unit's float. May need replacing. HD- hundred dollar