Fuel Gauge Problem

HELP! My 97 XJ Sport 4.0 has an erratic fuel gauge. I've checked all electrical connections and changed the dash gauge cluster. A local mechanic told me that most likely there was a short in the dash or the gauge itself. No luck. The gauge is pretty accurate when it works but it goes out constantly and drops to empty then comes back on and registers accurately again. When I'm nearly empty the low fuel light comes on just like it's supposed to. The needle just drops to empty driving, sitting still, no pattern at all. It's up and down all the time. Sometimes for a few seconds, sometimes for hours. Has anyone else had this problem?

You might check the connection where the plug goes in the back of the gauge cluster. They are known to be like that sometimes. The condition you describe would be the result of no power to the sending unit on an intermittent basis. So another words, loose connection somewhere. I can only think of three places that can happen. The gauge cluster, the plug near the gas tank and the tank to ground, which means you might have to clean some metal so the tank grounds properly

Thanks. That makes sense and was along the same lines I was thinking. I checked the plug and wiring near the tank and it looks good. I cleaned the plug so it would make good contact. It really wasn't even dirty I also checked the gauge cluster plug and the wiring in the dash area as far as I could trace it and it all looked good too. I have no skid plate on the gas tank and it is a plastic tank. Where would I look for a ground connection at the tank? I don't see one.

It would be in that harness. Probably a black wire or one with a black stripe

Thanks again. I'll look at the harness and at the plug near the tank. Maybe I should just reground it near the tank.