My 1990 YJ 4.2 is only getting 12.5 miles per gallon. It has been converted from a carbureted to fuel injection?
Fuel mileage
- Thread starter Skydriver44
- Start date
Flyer58
YJ Enthusiast
Gilaguy23
YJ Addict
One of my CJ's had a Howell conversion, cant say it got great MPG. The last CJ I owned was a "Jamboree Edition" 258, with a 3 speed auto and 2.73 gears. 55MPH is 2nd no problem, add bigger tires, 33's perhaps and your screwed power and MPG wise.
when the last time it had a complete tune-up, clean throttle body, and fuel filter, new air filter etc ? that {corn Gas} we have to use go bad after a couple weeks, maybe smaller amounts to use quicker ? there is so many variables it hards sometimes to figure out. good luck
Thanks, it has just been turned up with new air filter! I had an Islander that got better mileage…..
Gilaguy23
YJ Addict
The Islander either had a 2.5 or 4.0 eh? You'll never get 20 mpg like those two engines from a 258 IMO. Does it seem rich? what gears?,what tire size?
redbullet
YJ Enthusiast
Sunsport
Member
I had the 4.2 in my Islander. My current YJ has the 4.2 and has been converted to fuel injection. My tires are 10.5x31. I know the trans is a 409, but I don’t know the ratio.
I get a little over 13 mpg in my ‘95. Thought I would correct my speedometer error by changing my tires from 27’s to 28’s, which it did, but now I pretty much don’t need 5th gear, and it’s a 4.0. I checked my mileage on a 160 mile round trip to Lincoln, in 4th gear, and calculated 16 mpg. But driving around town, back and forth to work, etc, 13 mpg. I suspect 3.07’s for my gear ratio.
Going off my maintenance tracking app
95 YJ with 2.5L and mostly stock. 15.274 MPG (tracked for 8143 miles)
95 XJ with 4.0 and AW4 trans mostly stock. 14.597 (Tracked for 99,904 miles)
FWIW I've had 4 XJs and my 95 has the worst mileage by about 4-6mpg. Checking out the Fuelly website, it seems as though 95 is a bad year for fuel mileage on XJs.
95 YJ with 2.5L and mostly stock. 15.274 MPG (tracked for 8143 miles)
95 XJ with 4.0 and AW4 trans mostly stock. 14.597 (Tracked for 99,904 miles)
FWIW I've had 4 XJs and my 95 has the worst mileage by about 4-6mpg. Checking out the Fuelly website, it seems as though 95 is a bad year for fuel mileage on XJs.
1994 4.0 AX15 31X10's 3.07 gear and I get 19 like clock work...Running 6 oz's of Lucas with every tank.....
