The fuel gauge on my 88 Ultra isn't working. When the tank is first filled up it reads from 1/3 to 1/2 a tank. Then a few moments later it says empty. I have had it out of the tank checking to see if it was getting hung up or something. Is it bad and needing to be replaced?

Thanks Chad

 

Check the "wiper arm and contact" the contacts get corroded or oxidized causing it to lose contact.

A little electronics cleaner might be all it needs. The arm and contact are like a volume control on a radio, the arm moves with the fuel level float when it pivots, moving it across the contact surface changing the resistance value to the gauge. If it gets dirty or oxidized, the signal will not go through. YD

Hopefully it just needs a cleaning and is not worn out .YD

 

I'll try that. Any recommendations on a brand of cleaner?

 

I use CRC QD Electronic Cleaner, readily available at Walmart and Home Depot in my neck of the woods. Safe on plastics, no residue, and quick drying.

https://www.walmart.com/ip/CRC-Elect...1-Oz./16817418

http://www.homedepot.com/p/CRC-QD-11...30-6/202262505

I'm sure there are other brands that would work as well.

 

I build, rebuild, and restore vintage stereos and audio equipment as a hobby. This is the product that works. It is designed to clean off the oxidization from the contacts on potentiometers (wiper and contact surface) on vintage gear (volume, balance, base, and treble controls).

It's pricey but it works. Can get at any radio shack and a little goes along way.

https://www.radioshack.com/products/...nd-rejuvenator

Have you checked all wiring and connections? In addition (as mentioned), make sure the float is not fubar or hanging up.

I would suggest you get a meter on it and check the ohms at various float positions. With ohmmeter, you can determine if it is actually the float, or the gauge, or the wiring. YD

 

I have checked all the wires and can't find anything out of place. Pretty sure that the float isn't getting hung up but I'll double check. When I check the ohms what am I looking for? Do I want to complete the circuit (0 ohms) or have some resistance? I'll get some of the cleaner also. If I'm going to have it out of the tank might as well clean it too.

Thanks Chad.

 

Yes, the ohm resistance value changes when the level of the float moves. Cant remember the exact value but I think you should have 40 ohms when full and 240 when empty. YD

 

The tank sending unit is like a potentiometer. Measure the impedance of the coil itself if you can from one end to the other. The amount of resistance really doesn't matter as long as you don't get an infinite reading (an open).

 

had same problem it was broken wire on sender replaced with new now works great