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justinglow
06-01-2008, 04:39 PM
On my 98 MC the gas gauge goes to half a tank as soon as the key turns on and never moves. Even when full or empty? Could this be just a bad sending unit or the gauge? Is there a way to test for either?

helton333
06-01-2008, 04:52 PM
At the sending unit, simply disconnect the hot wire, hold it on the negative (helps to have a helper) - if it pegs the fuel gauge, the sending unit is gone.

dpolen
06-01-2008, 08:46 PM
There are two small screws on top of the sending unit to make adjustments, that would be the first thing to try before disconnecting anything. I adjusted mine quite easily last year.

justinglow
06-01-2008, 08:53 PM
There are two small screws on top of the sending unit to make adjustments, that would be the first thing to try before disconnecting anything. I adjusted mine quite easily last year.

Thanks I will try that first. Have to figure out how to get the back cover off first though before I can do anything else.

dpolen
06-01-2008, 09:00 PM
Thanks I will try that first. Have to figure out how to get the back cover off first though before I can do anything else.

Sorry, can't help you with that one...mine was under the back seat which just lifted right up...pretty sure yours is a little different than mine.

Oh, I just remembered...make a mental note of how far you're turning those screws, you might need to "undo things" as you get the sender sorted out. I actually unscrewed mine off the tank to ensure that the float was actually moving...thank goodness it was.

justinglow
06-03-2008, 08:48 PM
There are two small screws on top of the sending unit to make adjustments, that would be the first thing to try before disconnecting anything. I adjusted mine quite easily last year.

Before I start messing with the screws, Which screw does what? Is one + and the other -? Any pointers would be great.

JimN
06-03-2008, 09:23 PM
The original sender in a '98 isn't adjustable. They didn't start that until '99. It may have been replaced, however, but if it goes right to half a tank, it sounds like the original is still in the tank.

On the '98, it should have a larger aluminum tube with a yellowish float inside, that tends to get stuck or lose the magnets. Remove the sender and let it drain (it's not instantaneous) before doing anything else. Remove the two screws on the bottom to gain access to the float. Once you have it open, remove the float and make sure the magnets are still in place. If they aren't, they can be glued back. They usually stick together, so place them in a way that they would attract each other. Then, after noticing that the float doesn't slide freely, use a thin file with a square edge to open the slot a little. It won't change at this point, so just get it to slide freely without large gaps. re-assemble it and re-install the sender. It should work fine after this.

justinglow
06-03-2008, 09:47 PM
Thanks Jim I will try that first. Now I just need to run it this weekend and get all the gas out of it so I can move the tank out.

JimN
06-03-2008, 10:22 PM
If you remove the brackets and disconnect the filler neck/vent, it should slide out pretty smoothly. Remember, it's plastic on carpet, so it'll move fairly well. If it has 1/2 tank, it's cake.

JLeuck64
06-03-2008, 11:34 PM
I was into my 98 fuel sender a couple of weeks ago and here's a simpler way to access it. Just remove the assist struts for the rear compartment. Then remove the 6 or so screws that hold the access cover for the fuel shut off valve. Finally remove the 4 or so screws that hold the compartment tray down and lift it out. You will have real easy access to the fuel sender in about 10 minutes...
Good luck!

Also, if you do ever find it necessary to remove the tank completely, this step will make it easier to reach the nuts holding the rear seat back in place ( = Don't ask how I figured this one out!