fuel gauge off

[Germanshepherd]

read the tons of info on this common issue and my question is this. my 2004 TJ holds 19 gallons, how much of that is actually available to the engine? I thought I read somewhere that about 5 gallons is not available and just sits there.
I'm trying to determine how many miles I can run before I need to fill it up since the fuel gauge is goofy.
it will work until I get about half a tank and then the needle goes to E and low fuel light comes on.
The gauge works fine according to the self test.

once I figure my MPG, I can then determine about how far I can go before I need to fill up but if I only have 14 gallons of gas available (assuming 5 gallons is not available to the pick up unit), then that will help me determine when to fill up.

thanks

 

[StG58]

My '99 has the 19 gallon tank from the factory. The low fuel light comes on when there is about 3 1/2 to 4 gallons of fuel left in the tank. I can use all but a little less than a gallon of that. You could probably burn that as well, but that is really pushing the limit.

My understanding is that all TJ's have the same size fuel tank, but the amount of gas that can go in before the gas pump is kicked off varies. ...or something along those lines. Probably the best way to figure it out, is to grab a gas can with a couple of gallons of gas in it, and run the tank down until the engine sputters. Add a measured amount of gas, then tool on over to the gas station to fuel up. Add the amount of gas from the can to the amount used to fill up the tank. Subtract 10% or so for a safety margin. Multiply by average fuel consumption rate and, viola!, your base range has been determined!

 

[Chris]

My '99 has the 19 gallon tank from the factory. The low fuel light comes on when there is about 3 1/2 to 4 gallons of fuel left in the tank. I can use all but a little less than a gallon of that. You could probably burn that as well, but that is really pushing the limit.

My understanding is that all TJ's have the same size fuel tank, but the amount of gas that can go in before the gas pump is kicked off varies. ...or something along those lines. Probably the best way to figure it out, is to grab a gas can with a couple of gallons of gas in it, and run the tank down until the engine sputters. Add a measured amount of gas, then tool on over to the gas station to fuel up. Add the amount of gas from the can to the amount used to fill up the tank. Subtract 10% or so for a safety margin. Multiply by average fuel consumption rate and, viola!, your base range has been determined!

My thoughts exactly. I would use this same protocol.

 

[Jerry Bransford]

Every last drop in the tank is available, there is no reserve of unused fuel, nothing shuts the pump off until the tank is empty. The PCM shuts the fuel pump off when the engine stops running from having run out of gas.

The TJ's gas gauge is notoriously inaccurate, period. I don't even bother filling up until it's pretty well at the very bottom of the gauge and even then there's always at least a couple gallons still left in the tank.

 

[StG58]

Every last drop in the tank is available, there is no reserve of unused fuel, nothing shuts the pump off until the tank is empty. The PCM shuts the fuel pump off when the engine stops running from having run out of gas.

The TJ's gas gauge is notoriously inaccurate, period. I don't even bother filling up until it's pretty well at the very bottom of the gauge and even then there's always at least a couple gallons still left in the tank.

You are, of course, correct Jerry. My statement was not as clear as it should have been. The fueling nozzle on the gas pump at the filling station is what kicks off, not the fuel pump in the gas tank. There's a mod out there to fill the full 19 gallons in a TJ's gas tank. Don't remember what all is involved though. IIRC, all TJ's use the same tank, with the same factory P/N.

 

[Germanshepherd]

Thank you all for the replies. Weird, when I left work the gauge went back to normal. Will keep eye on it. Drove about 30 miles this evening and needle moved slightly and almost at 1/4 left, little over per beedle and went 175 miles since last fill up.

 

[Germanshepherd]

just wanted to give an update. gauge worked fine after it went back on. drove 195 miles and needle was at 1/4 tank when I filled it up today. took 12 gallons so still had about 7 left at 1/4 tank, seems like a lot of gas left for 1/4 tank so maybe needle is not exact but the good news is that my MPG was 16 and that is 90% stop and go driving and air on most of the time. at that rate I can go about 300 miles on a tank of gas. this jeep gets better mileage than my 2014 buick verano 4cyl.
pretty please considering jeep has 160k miles on it..