Help! My Car's Gas Gauge Isn't working!

Question

A man from an auto parts store was telling me that it is the fuel sending unit getting stuck on something.

What my gauge is doing is that it jumps up and down for no reason. Until my gas tank is half empty then it starts telling the truth and doesn't jump up and down. I have a 1988 Lincoln Town Car. It's a 5.0L V-8 Windsor Small Block and the engine is stock and runs great!

So what could it be? And most importantly what do I have to be replacing here?

Answer 1

Dont have a solution, but if you just fill up halfway all the time you can save gas. Less weight.

Answer 2

I would have to disagree with the hole in the float idea. If it was the float the fuel gauge would stay on empty till the tank was empty before it would drain enough to indicate a full tank when the tank was refilled.

The gent from the parts store isn't right either but he's close. It's the fuel sending unit but not due to hanging up on something. The sending unit has a metal contact connected to the float that slides along a resistant metal strip. What happens is the upper section of the metal strip gets some corrosion on it causing false readings. This is a common problem with older cars where the fuel tank was kept below half tank for long periods of time. The upper spectrum of the sending unit doesn't get used so it allows corrosion to build up. That's why it only works fine from half tank to empty.

To fix the problem you will most likely need to replace the sending unit. The reason I say "most likely" is it's possible for the problem to correct itself if you go through several cycles of full to half to full to half tanks. This will let the sliding contact go back and forth possibly clearing the corrosion over time. If that fails to work then you will need to replace it.

To replace it you will need to drop the fuel tank. This is best done with two people, one to hold the tank (after you empty the fuel out) while the other person removes the mounting hardware. You will need a replacement sending unit and the gasket for it. If you need to take it to a shop it should only take about 2 hours labor for the repair.

Don't forget one thing. If you do it yourself DO NOT try to smoke a cigarette while working on the fuel tank. :-)

Answer 3

Nice car!!

This problem sounds like you have a hole in your float for the sending unit and it is getting full of gas and making it heavy,which causes the float to bounce,Ford copper/brass floats are famous for doing this ,the same problem happened to me on a ford ranger truck,I replaced it with a plastic/neoprene float of the same type that I got from Napa auto parts.($9)