YJ Gas Gauge Sending Unit Modification

A little background on my 1993 YJ: I purchased it from my friend Joey in April of 1999. I am the third owner and while Joey owned this Jeep he had the local dealership fix the Gas Tank recall. Joey neglected to tell me that the gas gage didn't work fully when he sold it to me. After running out of gas a few times I decided to figure out what is wrong.

The scenario: My tank is a 20 gallon tank and the engine is the 4.0L with AX-15 5-speed transmission. I noticed my gage would not go below 1/4 tank. I read online somewhere (forgot where) about this "cup" that sits inside the gas tank. I read that this "cup" was limiting the travel of the gas gage sending unit arm. So, I decided to drop the gas tank and figure out if this was true.

My gas tank on the ground below my jeep. I waited until there was very little gas in the tank (5 gallons to be exact - see white bucket) to drop the tank.

The 20 gallon tank. Notice the left strap missing. I did not realize I could drop the gas tank and the skid plate as one. In trying to take off the straps I broke the left strap. A $30.00 mistake. The skid plate can be taken off by loosing the 4 bolts on the front of it as well as the 4 bolts in the rear of the tank.

I found it easier to disconnect the filler hoses up at the nozzle than at the tank. Be careful to not tear the vent / gas-to-engine lines when lowering the tank.

After I did this I found that "cup" lurking inside my tank as seen to the right.

If you look past my shadows you will see how over time the gasoline has warped the plastic "cup". This warping of the cup I believe is the cause of my sending unit not completely registering full empty.

To prove this I connected the sending unit to the wiring harness and turned the key to the "on" position. When the arm is down, the gage should read EMPTY, thus when the arm is up the gage should read FULL. Mine did exactly that, which told me that there was no electrical problem but rather a mechanical problem.

Now that I know what the problem is. How do I fix it? Do I completely remove the "cup"? Or do I risk losing $150.00 and bend the arm on the sending unit? I heard that the "cup" is there to prevent excessive debris from clogging the pump intake. So, I took the more expensive route and bent the arm on the sending unit.

Bending the sending unit arm is tricky. I had to bend it in exactly the right spot so it would go over the side of the "cup" and still register the correct amount of gas for empty and full. After a few tries I got it bend perfectly as seen below. At empty the float sits a little higher than it used to (somewhat of a good thing).

After the sending unit arm was bent. It was time to put everything back together. Installation is the reverse of taking it out. Now my gas gage goes down to E.

Any comments or questions can be forwarded to : dougyfresh@vt.edu