Fuel Gauge is jumpy, Could it be something other than fuel tank sending unit? Options

[ptravnic]

Anyone had the "jumpy" fuel gauge problem before?

I have a 72 that I've had for ~20yrs. The tank was treated sometime in the mid-90's and I haven't had a problem w/fuel delivery or gauge reading...until now. The car sat w/only a few gallons of gas for the past 5yrs. It got its first full tank on the drive back from Brad Mayeur's last month (he did some work over the winter)

While fuel delivery is not a problem but my dash gauge jumps around a bit and sometimes doesn't get a reading at all.

I'd like to get this sorted before I get it in for paint - just in case the "fix" involves taking the tank out. I know tank removal can be done without scratching the paint but I'd rather not run the risk.

Before I pony up to a new sending unit, could it just be dried out or an intermittent ground somewhere on/around the sending unit?

-pt

[Mike Bellis]

If you're going to paint it, pull the tank first.

Sounds like a bad or dirty sending unit. There are 3 wires to the sender located on the top of the tank. The brown wire is ground. It is bonded next to the fuse panel. Make sure your grounds are tight. The green wire is the signal 10-70 ohms. The black is the low fuel light.

McMark did a write up on cleaning the sender. Remove it, take off the little nut at the bottom. Gently persuade the sender apart. There is a float and a resistance wire inside. Be careful if the wire breaks, game over. Once apart, use some laquer thinner to clean the wire and terminals. Use an Ohm meter to make sure the resistance changes smoothly. re assemble and test with the guage. If it doesn't fix it, find a used one or fork over $140 for a new one.