Jeep fuel gauge problems? Read around on the internet and you will see that many YJs and XJs have this issue. Especially ones that have been wheeled a lot. All the dust, dirt, water and mud get all caked into the plugs causing connection issues. Which leads to the most common fix for the gauge issues. Clean the crap out of them .. kinda pun intended :-) . Seriously, the number one fix for faulty instrument panels is taking it apart and cleaning all the caked up crud in the connectors.
Having problems with the gas gauge? It seems as more time than not the heart of the problem lies in the gauge cluster its self. All those copper contacts usually have some corrosion film impeding proper contact.
Take out the screws that holds the dash trim in place. Once you get those out there are 6 screws that hold the cluster in the dash. As you remove the cluster from the dash frame be careful not to snatch the dash harness causing more connection issues. On back of the cluster is a film that has copper tracings built into it. Where the dash wiring harness plugs into the cluster contacting the copper tracings is one problem area. Also, where the gauge electrical posts contact the tracings is really the bigger problem areas.
A great cleaner for all the copper connections is good 'ol hot sauce. Ya know, the hot sauce that you put on soup beans or a sandwich. Brands such as Tabasco or Louisiana hot sauce are the most common. Just rub a light coat on the contacts and allow it to sit for a few minutes. Then with a clean rag wipe it all clean. Look at that copper shine! Check out the video below how I did my cluster. All gauges worked great once I cleaned everything.
One very important tip. Each connector you get clean, put some dielectric grease on EVERY electrical connection. I believe the Permatex brand calls it "tune up grease". Whats that going to do for you? That grease does not hinder the electrical connection at all. What it does do is prevent more corrosion from forming. Not only that it also helps seal out water from those nice clean connections you established for your gauges. It helps lessen the reasons why your Jeep fuel gauge problems should re-occur.
Need a schematic for the fuel pump connection? Here is a page of the out of the service manual. Hope it helps!! Click the image to get cha one!