TJ getting 3 mpg
- Thread starter indio
- Start date
John Scoggins
TJ Enthusiast
Sounds like you might want to tighten the "Loose Nut" behind the wheel as my dad would tell me in my youth. As stated before, if you are truly getting 3 mpg the jeep would stink like un-burt gas, and have some black smoke and probably raw gas out the tail pipe.
Double check your miles driven with GPS and make sure the son is not sneaking the vehicle out and resetting the trip hoping no one would notice (I have not a clue where I would get such a thought).
As for the EVAP code, get you a cheap smoker from amazon, they work pretty well and you can use it as many times as needed.
Double check your miles driven with GPS and make sure the son is not sneaking the vehicle out and resetting the trip hoping no one would notice (I have not a clue where I would get such a thought).
As for the EVAP code, get you a cheap smoker from amazon, they work pretty well and you can use it as many times as needed.
Tray Burge
TJ Addict
Go try siphoning gas out of your TJ's tank. Short of disassembling the filler neck assembly it's not possible.
Does it always smell like it's running rich (high fuel to air ratio)? That's normal for a cold start condition until it warms up.
If you don't already have a bluetooth OBDII reader, I recommend grabbing one. I use the Torque app, but there are others. Once you're fully warmed up, what does the coolant temperature reading say? It should be around 210 degrees or slightly higher. If it's lower, replace your thermostat with a 195 degree model ASAP.
And, like Jerry said, I would also suspect the O2 sensor. If you don't know how old it is, just replace it.
If you don't already have a bluetooth OBDII reader, I recommend grabbing one. I use the Torque app, but there are others. Once you're fully warmed up, what does the coolant temperature reading say? It should be around 210 degrees or slightly higher. If it's lower, replace your thermostat with a 195 degree model ASAP.
And, like Jerry said, I would also suspect the O2 sensor. If you don't know how old it is, just replace it.
Kids are kids, most sons are more like sons and you never know about any friends. Maybe one of them reset it at some time and we may never know why.
Some other ways of getting terrible MPG:
1) Idling for hours while listening to the stereo because last time you listened to it you killed the battery. (Don't ask how I found this out 35 years ago)
2) Being very stuck or helping someone else that was very stuck.
3) Both 1 and 2 combined.
A long drive in a Jeep is always a great idea even if it proves it was the kids doing something by giving you somewhere closer to 12 MPG. Maybe even take you son with you.
Either way, HAVE FUN!!
That is true. Siphoning became difficult some time in the 1980s IIRC. I remember the good old days when you could actually see the gas in the tank when you took the cap off.
Impossible to do a mileage check with a 42 mile run. Best to average a few tanks of gas and do the last fill up at the same pump as the first fill, parked in the same direction.
I guess I'm old and honest. I haven't siphoned out a tank in decades. And that was as a kid helping fix something of ours.
Now they drill a hole in the bottom of the tank and drain the gas out. Which seems like a lot of effort for little gain.
BrunoPizz97
TJ Enthusiast
I +1 this, very true theres no way that youre getting 3 mpg without noticing the car is running rich on fuel or running rough. My 97 used to run rich so I did a whole tune up (plugs,wires,injectors,o2 sensors) car runs great. I am running 33" tires with a 4.10 gear ratio on my dana 30/35 get on avg 250 miles a tank sometimes 300 if im lucky, I dont have a fuel sending unit that works so i prominently rely on my tripometer
I don't rely on the trip odometer when I calculate. I take the difference between odometer readings then use the trip meter as a check on my math.
BrunoPizz97
TJ Enthusiast
If it was dumping that much fuel the oil would be thin, smell like gas and over full. The engine and would probably need a rebuild.
I second the GPS just to know for sure what your actual speed is, how far off speedo and odo are.
Are you sure the trip was not reset by mistake before you went for a fill up? 3mpg is normal for an M-1 Abrams.
We would get ~9-10 mpg with our old Chevy truck after the engine was replaced with a carbureted 350. I had a friend in high school with a 396 Chevelle that got a little worse gas mileage than that, but gas was under a $1/gallon then. Nothing like 3 mpg.
My brother gets 9 mpg while pulling a large boat or camper with is 1 ton dually crew cab. So if the miles are right, it has to be leaking somewhere.
My brother gets 9 mpg while pulling a large boat or camper with is 1 ton dually crew cab. So if the miles are right, it has to be leaking somewhere.
It is possible, a hose small enough to sneak through the cage. Helped a buddy with his fuel pump and he was able to siphon down to 2gals left in the tank.
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