Troubleshooting a gas guage

Well,, I guess it time to fix it !! At least that is what my wife strongly suggests. And since the tank only has the 5 liters in it, that I carried to our surprise roadside parking spot,, I guess she is right !!

So where would one start,, if all you know is that the guage does not work ?? What kind of circuit should exist between the sender and fuel guage anyway ?? Are there any common issues to be aware of ???

thanks,
Alan

What gauges are they - CMC/Vintage, VDO, 914 VDO, 356 replica? An ohm meter will let you know if the sender is working - as when arm is moved the resistance will vary. Does sender match ohms the gauge is expecting? Got good ground to sender and to gauge?

Hi, Wolfgang,,
The guage is a VD0, as supplied by CMC,, I believe. I am going to borrow a meter to test the sender this week. I guess I should be able to just clip the sender on,, and then measure the change in resistance as the tank is filled ?? That should either confirm or rule out a problem there.
thanks,
Alan

i just had the same problem and it was just a faulty ground wire. the tank itself needs to be grounded.

Make sure you have no gas fumes present before proceeding.

With the key switched to the ON position, disconnect the sender wire off of the connector on the center of the sender and ground it, the gauge should then read full.
Confirm a good connection from an outer screw on the sender to a clean chassis ground.
Confirm 12v at the gauge. ~Alan

on a VS the tank sits on plywood i believe, how is the tank grounded to the chassis then, does a ground wire need to be added to one of the 4 mounting clips?

There may be a pair of wires attached to the sending unit. I would look closely at where the wires actually go; one will eventually lead you to the fuse box, and the other will lead you to the chassis somewhere. The one that goes to the fuse box will probably also lead you to the gauge. The gauge may also have a ground.
I have the gauge and the sending unit on the same fuse.
Just like any other electrical problem, I've always been a fan of checking easy first. Look at the fuse, and look at the grounds.
Mine is sharing a ground with my horn, below and in front of the tank.
It occupies my eighth fuse. Yours will likely be different.

"on a VS the tank sits on plywood" Yes you need a good ground to clean chassis metal. For test purposes run wire from one of sender screws to the battery ground (if battery right there in the front.

All of the screws except one should have nylon washers.

The other one should be copper.

Attach the ground wire there.