Carb hesitation

Ive rebuilt my carb, because when I bought my Jeep it didnt have a working carb on it. So up to this point Ive been trying to tune it. The problem Im having is hesitation when I try to throttle out of stuff in 3rd and 4th gear. It hesitates really bad when I shift into 3rd gear and if I hold my foot into it it wants to backfire. 4th isnt as bad but still there. First gear does it when its cold, but seems to be ok when it warms up taking off the line. Ive checked everything I can think off. I adjusted the float levels to 1 3/32 and 1 7/8. When I measured the float level, I measured to the seam line on the brass float. I thought they should be a little more level than this one looked. I have the timing adjusted to 5 degrees and my dwell set at 30 degrees. I adjusted the accelerator pump lever. The things I have not done is changed plugs, wires, rotor, or cap. Ive been wanting to convert to HEI, but since I cant seem to figure this problem out, I want to wait, inless it might fix the problem. I done a search on this and everything points to accelerator problem or vaccum leak. Ive adjusted and checked both. I dont know if this could have something to do with a mechanical advance problem or not. The other thing I was unsure about is the gasket I used to mate the carb to the intake. Its solid so it blocks to holes between the bolt holes for the carb on the intake. I used a different gasket before I pulled the carb off to check the accelerator ball. I was still having the same problem. Forgot to add, manuel choke.

 

No I have not checked my fuel pump pressure or volume. Its a new pump I put in a week ago. I well pull the plugs and check them. This is going to sound kinda elementary, but how do I adjust for lean/rich. Dont I have to change the jets? Thanks gor the help.

Hey Patrick were did you get your soft top?

 

I pulled a plug and it looks a little whiter then it should be I think.

 

jeepin
I was havin some issues with my carb, so I took it to a tunex.
They hooked up the computer, pulled the carb top, dropped in some new jets.
never had any more issues for couple years now.
I knew the mechanic and he is good, so maybe I lucked out.
For the cost it was way better than me trying to figure it out.
CAM

 

Well I just went and rechecked everything and as far as I can tell everything is working the way its suppose to. I do have a different set of jets that I think Im going to try and through in there and see if that makes a difference.

 

I did find out that if I pull my choke out a little it revs up with out as much hesitation. This would mean that with the choke off, its running lean?

 

So I need to add bigger jets right. Shouldnt the jets that came in these worked. Or did the dealerships rejet according to were they were sold?

 

Wow, this sounds very familar - I had exactly the same problem after a carb rebuild (V6, 2G). It was driving me crazy and I did a LOT of research. Everything indicated a vacuum leak but I couldn't find one.

I pulled the carb off a few times, took it apart a few times, changed the accel pump twice, hooked up a vacuum gauge many times, reset the timing a few more times. . . .

Eventually the hesitation completely went away on it's own - I never did figure out what it was. If you google vacuum leak there's a lot of info out there. Get a vacuum gauge - cheap from NAPA. I don't think it's your jets. Keep driving the vehicle don't just park it and work on it.

If you do figure it out please post.

 

I have a vaccum gage on it. Its reading about 18in at idle.

 

Ok, so I replaced the plugs, cap, wires, and points. Couldnt find a rotor for it in town. Still running like garbage if anything its worse!! Im losing my mind on this deal. The hesitation is horrible. I took it out wheelin yesterday because I thought it was running better. I climbed this hill and it died on me. Took 15 min to get it going again. Then once I got it going it wouldnt idle. Im starting to wonder if it could be my vaccum advance. I tried diagnosing it according to the book. Rev the engine to around 2k, pull the advance hose, and the timing mark should gradually move back. Well when I pulled the line, the timing mark dropped suddenly. Im not sure if I did the test right or not. I dont have a vaccum gauge, that you can pump. Other wise Im back to it running lean? When I do pull the choke out a little it revs like it has no problems. Doesnt want to idle though when the choke is out. Anyone else got any ideas? I open to all.

 

doesnt sound like any electrical sound like its running lean reves up with choke but wont idle will it run down the road at half choke if it will run with full or half way out but not with choke its starving for fuel but could still be a air or vacum leak causing it to run lean.

 

I would be checking for a vacuum leak anyplace else, such as maybe at the carb or manifold gasket, or a cracked vaccum tube, or something not directly carb related.

A slight leak may not show up at idle, but kills power when sudden load is applied. Pulling the choke out can somewhat compensate under that condition.

Good luck

 

I didn't see this mentioned, but my first thought was to check the accelerator pump. Do you get a shot of gas when you open the throttle?

 

Thanks guys for the suggestions. Ive tried and tried to find a vacuum leak. Ive been using starting fluid to try and find it, but I cant find anything. Is there a better thing to use when trying to find a vacuum leak. Ive heard people using propane? I agree, it does sound like fuel related but I cant figure out how. The accelerator pump is working and shooting gas, Ive messed around with it and cant seem to make it better. I changed jets to the other set I had but that didnt do anything. Can the intake leak from inside the engine? In other words, the bottom of the intake?

 

18" of vac is good; likely no vac leak or very small if any.
a bad ballast resistor or bad point setting, even a bad or shorted condenser can do this as well.
other than that, I think we're back to the carb.

 

Alright, How old is the gas? It does not store well. I agree that 18" of vacuum is good, so it is not likely to be an air leak. Did you set your float level per the manual?

In answear to your question about the jets, yes you would install larger jets to get more fuel. Yes, the dealer would either order it with the correct jets for his altitude, or he would change the jets appropriatly. So if you live in L.A. and the Jeep came from Denver or worse, Leadville Colorado, Theres your problem!

It sounds like this Jeep has been sitting for awhile, how long? Years or just two months? Over three months and your fuel itself is suspect. Now some folks out there will argue about that, but I have had gas go bad in three months time. The rig would just run like crap. These older low compression engines are more forgiving then the newer ones are. Still...

Keep us updated, especially when you find out what it was! Good Luck, Matt W.

 

Well the gas is new. I havent replaced the ballitster, I have replaced the the condensor and the points. I think maybe Ill keep try using different jets

 

So, I had a horrible day today, so I worked on my jeep for some relief. The good news is I some how got the hesitation reduced alot. I think it might have had some gunk in it somewhere that I blew out tonight. I basically took the carb apart with it still on the engine. Maybe it was slightly plugged somewhere. I also messed with the vacuum advance a little bit and made sure it was working properly. It still has a little hesitation in first gear when I take off with it. It really has emproved alot though. I cant figure out what might be the problem now, but its getting better. It well take off then almost die then take off. I dont know?:?