MPG '87 YJ stock tire stock height

[duckkillerclyde]

I have an '87 YJ stock tires and stock height. I put a motorcraft carb on her because it would not idle worth darn with the throttle body and all of that emission garbage on it.


I finally burned one tank of fuel in it. I got 11.5 MPG. I really expected better. I had my foot into the entire time so I guess it is not too bad. I also have the auto transmission but I also adjusted the shift linkage so I am shifting at 1800 RPM.


What kind of MPG are you guys getting darting around town in a 4.2?

 

[808CJ7]

I just ordered a motorcraft from mike on eBay. Running a Holley 2 bbl. right now. Mpg. Sucks literally. It's in a 76 cj with a six inch lift and 33s so I guess it's to be expected. I'd say 10 mpg. Did you get a chance to go Offroad with the motorcraft yet? Just wondering how's it work in off camber situations and steep inclines.

 

[duckkillerclyde]

I think you missed the part where I'm all stock and a rookie at jeeps. Haven't really been what 'real' jeep guys would call "off road", but when I play around on 3/4- piles in the yard I have to stay into the throttle or it will die.

 

[duckkillerclyde]

If that is what you meant...

 

[808CJ7]

Pretty much. I got the same motor and soon to be same carb. So I just was wondering how it worked in the ruff stuff. Thanks

 

[superj]

i get between 9 and 12.

hit the little link on the bottom of hte page to see the history for a few months on the mileage my almost stock 87 getshttp://www.fuelly.com/driver/busemans/wrangler/sig-us

 

[duckkillerclyde]

filled up today and I got 19.16 MPG driving like an old person but still did a little playing in the snow. went up and down some hills too. like 20 miles of up hill and a gain of 2000 feet.

 

[superj]

You sure? That's amazing gas mileage for a carb'd 4.2

 

[duckkillerclyde]

You sure? That's amazing gas mileage for a carb'd 4.2

positive.

I will need fuel again maybe by the end of the week so I will check and post again.

 

[superj]

cool. if you are getting that, let me know what your timing and idle are and what point your trans shifts at so i can try and get the same results

 

[duckkillerclyde]

cool. if you are getting that, let me know what your timing and idle are and what point your trans shifts at so i can try and get the same results

I have auto transmission.

Idle speed after choke is off is ~800
Timing I checked the other day +9 degrees
Shifting at 1800 RPM

 

[superj]

almost identical to mine. mine is idling at 750, timing is 10, i just set it this morning, and shifting at 1500 on granny driving and 1800 on normal driving.

i just flipped the advance plate on my distributor though so i am hoping to see better mileage. instead of it being in the 13r slot, i am now in the 18r slot. it made a huge difference in off line acceleration so i am hoping it will help the mileage too.

 

[carnutt]

i have an 89 yj has carb update and ignition bypass.
i get rather decent meilage but i had to install a manual choke n choke has to be on or it'll stall at idle.timing is 10deg.idle screw is at max..any suggestions..?

 

[carnutt]

and its standard not auto transmission

 

[duckkillerclyde]

and its standard not auto transmission

I stall at idle if I punch it. I don't know how old you are but I'm getting to the age where I don't care if I pull out in front of someone.

 

[808CJ7]

i have an 89 yj has carb update and ignition bypass.
i get rather decent meilage but i had to install a manual choke n choke has to be on or it'll stall at idle.timing is 10deg.idle screw is at max..any suggestions..?

Sounds like a vacuum leak to me

 

[superj]

Of you have the idle screw all the way open and it dies with out the choke pulled a little, you have a pretty big vacuum leak. Check all your nuts and bolts on the carb and intake and check all your vacuum lines.

 

[duckkillerclyde]

I spray starting fluid around carb gasket to check for leak. If engine speeds up, you have leak.