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Gas gauge messed up

TheVision89

NAXJA Forum User
I recently bought my first car, a 98' Cherokee Limited and from the first time I drove the car 200 miles home, I noticed the gas gauge was off. When I filled her up for the first time, I immediately noticed that the gauge went way quite a bit past F. It was also surprising that when i got home, it was only at a little under 3/4th of a tank. 200 miles on a theoretical 1/4 tank? seemed absurd.

I then fixed some other stuff on my XJ after it overheated due to my error (long story). When I finally started daily driving it, I noticed that the gas mileage was horrible, and still is today.

I understand this isn't a prius, but from home to school and back (12 miles round trip), I used a little over one whole notch to the next on the fuel gauge, which seemed peculiar.

Later I noticed that when I'm on half a tank on the gauge, my overhead console says DTE: 100 miles, meaning that my tank is only estimated to get 200 miles? Bone stock, seems weird.

Does DTE mean until 0 gallons or is there still something left after it says 0 (I have not dared to try.)

Is there anything I can check/fix/replace that might correct my gauge, and anything that might cause this problem.

My Fuel injectors/Rail are sort of rusty would that be it?
 
I think you should get some better data before assuming its messed up.The gauge isnt "linear",meaning its seems like the first half of the tank "seems" to last longer then the second half!
 
Sounds normal to me. My max range on the highway is about 250 miles sometimes more sometime less. My gauge read just over 3/4 when tank is full. Never have seen a truly accurate gas gauge in any vehicle in 30 years of driving. O-head computer and gas gauge really have no relation to each other, never seen one of those that was accurate either. Me, I know my max range, so when I hit 200 on the odometer I look for go-go juice, gauge and light will say I ran out at mile 150.
 
You may want to check/test the fuel sender sensor unit. Have you done a tune up at all? Oil change, fluid changes? plugs/wires/ cap/rotor? If not I would definitely start there. And I would also run either seafoam or MMO thru your fuel system next tiem you fill up, can help clean gummed up injectors, lines etc. Pull the intake tube check/clean your throttle body with TB cleaner ONLY! Not carb/TB cleaner. Maybe run the seafoam thru your intake via the brake booster hose? How many gallons does it take to fill up?
The OHC display is not that accurate, at least most are not.

I have a Renix XJ, but all highway usually 330-400 depending on how much load I have and what teh terrain is like. City/very little highway usually 250, and thats not running it dry either.
 
my ohc fuel mileage gauge always checks out within .5 miles of what the regular calculating tells me. 21.5 mpg, about 350-400 miles out of each tank.

it does, however, occasionally just drop to zero from full/half but comes back on if i shut down & restart.
 
Fuel rail has nothing to do with it.

I would check the fuel level sender but it's a pain in the butt to get to on a 98, even more so than on earlier years. Really not worth bothering with, just get used to it. Use your trip odometer to decide when you need gas. Also stop using the "quarter tank" measurements, they are very inaccurate, figure out your gas mileage by resetting the trip odometer, filling up, driving till you think you need gas, reading the trip odometer, and filling up again, preferably at exactly the same pump. Divide odometer reading by gallons added. Any "x miles on a tank" and similar statements are worth exactly as much as the paper they are printed on... nothing, in this case.

My gas gauge in my XJ reads 1/2 tank when it's full and empty when it's anywhere below 1/2 tank (my fault due to some modifications I did, working on fixing it eventually.) The gas gauge on my MJ reads empty when full, and full when empty (due to the RENIX fuel level sender/pump assembly I'm using, it's an OBD-I MJ) but otherwise is pretty close to accurate.
 
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