'93 YJ Fuel gauge / sending unit 20gal.

[dandoc]

From what I've gathered from researching previous posts, my problem is not unique. I own a 1993 YJ with a 4.0L engine & 20 gallon fuel tank. There have been some issues with the fuel gauge / sending unit that I have attempted to correct, and have been successful with... to a point.

The problem I present to you is this: the fuel gauge stays pegged at "Full" until about 1-3 gallons of fuel remain in the tank. Then the fuel gauge needle bounces from full to empty, or to some point inbetween until the tank is nearly empty. (The needle bounce occurs mainly when I drive over bumps in the road and when cornering. My guess on that is the fuel is sloshing around making the float arm in the tank move up and down.)

In a previous posting on this issue someone mentioned cleaning the contacts at the fuel gauge itself. I attempted this today, only to find the contacts clean and not corroded. Ruling out that possibility, this leads me to believe the sending unit is not sending the proper signals.

I've already done work within the fuel tank to allow the float arm to drop to the bottom to solve the problem of gauge reading 1/2 tank when it was actually below that level. At that time I also replaced the gasket at the top of the tank (the old one was cracked and looked like someone used silicone on it), and inspected the sending unit. I found no apparant problems with the sending unit, minus minor surface rust on the metal components from water in the tank (previous owner).

Could the rust be causing incorrect electrical signals to the fuel gauge? Any other ideas? I don't want to spend $350+ on a new sending unit/fuel pump combo from the dealer. Thanks in advance for any advice.

 

[Bounty__Hunter]

Sounds like a corrosion problem if you've had to clean some rust in the tank. The float arm moves a metal contact along a contact grid, thus transferring the position of the arm into an electronic signal. Sounds like the contact grid on the sending unit is nearly all corroded.

You can often change just the sending unit, transferring the pump over to the replacement sending unit.

I had an extra one, but I nearly bent it in half when a rock dented in the bottom of the fuel tank.

 

[dandoc]

It's a plastic tank, so only the sending unit has the rust. I did notice the grid coil that the float arm makes contact with when I had it out. There may have been some corrosion on the coils, but I cannot remember. Either way, I'll look at that in more depth the next time I drop the tank (should be next month... frame needs repaired at that end). If nothing else, I'll just live with it and keep an eye on the trip-o-meter.

 

[mud4feet]

...........If nothing else, I'll just live with it and keep an eye on the trip-o-meter.

When you mentioned $350+ for replacement, that's what I was going to suggest.....................I know it sucks, but it is a workable solution (just don't let mudwoman drive it!!!:lol: :lol: :lol: :lol: )





...................oops!!! I think I might have gotten myself in trouble!!:shock:

 

[Sparky-Watts]

.........oops!!! I think I might have gotten myself in trouble!!:shock:

You seem to be doing that more and more often lately.....bad habit, Brother Mud, bad habit!:shock: