MC2150 choke pull off troubleshooting

[nlcj]

MC2150 troubleshooting dies when cold

Hi all,

79 CJ7 AMC 258 i6 / 4.2l

I got a mc2150 kit of that ebay guy a while ago and of course it wasnt all he cracked it up to be.

Problem:
Start up and let warm for a minute or two. Idle is a little ugly but ok. When I push the gas in gear (starting from stop or changing gears) it dies. Does not happen when engine is hot. Electric choke opens fully after two minutes.

Im new to this. Could it be that Im flooding the engine because the fresh squirt of gas is hitting the relatively cold manifold? Im talking about 5-10deg C (41-50F). Bad power valve or something? Rig seems like it should have more power than it does anyway. I experience slow acceleration at the best of times but its my first cj so I dont know.

Things Ive tried:
accel pump looks fine, rod is in second hole from the top on the linkage, I get a squirt of fuel immediately. Timing is at around 8*. Plugs and wires are all new. team rush done. new fuel filter. advance seems to work/move fine but I havent rigorously tested it.

really appreciate the help

 

[Torxhead]

So everything is fine after engine warm up? I see you list the tranny as a T-150 , what size tires are you running? You have covered the usual suspects so far. Another thing you could check would be fuel pressure and carb float level.

 

[nlcj]

Tires are 31s.

thanks, ill look into that and report back. I would say that yes everything is fine after its warm but I still feel its lacking power

 

[mtnwhlr]

Check for vac leaks at the base where it all bolts to the manifold.

 

[Dan77CJ7]

If everything is working after the engine is hot I would say nothings wrong my jeep does the same thing if I don’t let it get operating temp before I take off i’m kind of weird like that though I never run my jeep cold at least 8 minute warm up before I even think about putting a Load on the motor

Have you used a vacuum gauge to tune in the carburetor or are you just running the carburetor right out of the box?

 

[nlcj]

Thanks! I was kind of wondering if its normal or not. Its my first carbed road vehicle and am still learning the quirks. I know my old atv runs like junk until its warm so its probably similar. Im always nervous about first pulling out into the main road but maybe I just need to wait a tick.

float level is to spec

I sprayed carb cleaner around all the lines and the connection to the manifold and didnt notice a change in rpms.

I should also note that theres a slight miss at cold idle and i can see the tach drop in sync with the miss.

I am just running the carb right out of the box aside from the idle screw adjustments. Since the seller made such a point about it being set up for my elevation, I didnt mess withe the mixture screws. I'll investigate with the gauge and give an update for anyone else in the same boat.https://www.jeep-cj.com/forums/images/smilies/beerchug.gif

 

[Lumpy Grits]

Try very soapy water in a spray bottle, for vacuum leak hunt'n.
You'll see the bubbles get pulled inside...
Make sure BOTH idle mix screws are turn'd out the EXACT same amount.
Try them both a 1/4 turn farther out and a 1/4 turn in from the setting you have now.

LG

 

[JR74CJ5]

I agree with others above too - first and easiest thing to check at this point is the idle mixture screws on the front, and tuning with the vac gauge.

I would tighten the mixture screws down (carefully! do not tighten past point you feel they slow - you'll damage the needle - you'll feel it where it should stop, just be light with your pressure) counting the turns you move each of them. I'm not sure your elevation, but you can try anywhere from 1-1/2 to 3 turns out equally to start with tuning. Tune them together 1/8 to 1/4 turn at a time each when tuning.

But, Also I experience this as well if I do not let it warm up fully and kick down the choke idle before leaving... Seems to run crappy for a bit longer than if I just let it warm up before leaving.

Just some pointers since you said first carb'ed vehicle.