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bmxer0122 06-28-2013 12:44 PM

Stalling problem
Hey everyone,
My jeep has recently developed this obnoxious problem and I am completely stumped. When driving it will be completely fine then occasionally when idling (at a traffic light, rpm drop when downshifting, rpm drop when taking a slow turn) it will sputter and stall. I have a weber carb on top of my 4.2. The weber is freshly rebuilt (within the last three months) and it's tuned to idle around 800 rpm and when it runs it runs pretty smoothly for a carberated engine. My first thought was that it may be a fuel problem so I dropped the gas tank, cleaned it out, ran new lines, new fuel pump, and new filters. The problem still occurs. It seems to happen randomly but once it happens once it will happen every time it idles until the vehicle sits for a long period of time (such as overnight). I was told that it could be a timing issue or an exhaust blockage (not from a reputable spurce), would either of those cause that? The exhaust on it is a flowmaster muffler welded into the stock exhaust. Any help or suggestions would be greatly appreciated!

bmxer0122 06-29-2013 06:41 PM


psych 07-09-2013 06:35 AM

Sounds like mine. I only just got on the road with it and I have experienced those same conditions and just as randomly. If I hear or figure out what it is, I'll update you.

bmxer0122 07-09-2013 06:45 AM

Thank you!

BretB 07-09-2013 07:34 AM

Not sure about the "until the vehicle sits for a long period of time" scenario, but I experienced the idle dying syndrome and it was dirty battery terminal connections.

bmxer0122 07-10-2013 07:03 AM

Usually the long period of time is me geting frustrated and walking away and not messing with it for a day or so. The battery (optima red top) is clean as well as the connections. The only thing I can think of would be maybe an exhaust blockage maybe that gets jarred when driving causing it to block the out flow? IS that plausible? How do you even check for that

BretB 07-10-2013 07:31 AM


Originally Posted by bmxer0122 (Post 15661289)
IS that plausible? How do you even check for that

Sorry, I don't know... Someone will.

Siva283 07-10-2013 09:00 AM

I am not a carb guy but my first thought is vapor lock.

bmxer0122 07-10-2013 11:44 AM

^That makes excellent sense! Esp since it seems to happen when it is hot out and the engine is warm. Any tips on ways to prevent this? (I will also be scouring google)

Old4X 07-10-2013 12:02 PM

How much fuel pressure do you have at the carb inlet?

What vacuum reading do you have at idle, warm engine.

How much slack in your timing chain (in crankshaft degrees)?

stu1021 07-10-2013 12:05 PM

Make sure fuel lines are routed away from hot exhaust. I would check the carb float setting to make sure the fuel level in the bowl is not set too low (just shut it off in a level spot and pop the top plate off the carb to see where the fuel level is) and also the fuel pump output (you can disconnect the fuel line where it goes into the carb and put it into a glass bottle/jar then turn the engine over and observe the output). Make sure you are getting something over 13 volts at the battery when the engine is running at idle and accessories are turned on. Also, check all of your vacuum lines to make sure there are no leaks. Another thing to check for would be the advance spring and weights in the distributor. If the springs are stretched/loose or the weights or vacuum advance unit are sticking this could cause sudden changes in timing as the plate shifts and could account for the problem you are having. Here is a link to a good article to look at: of course the stock carb is different but there is good info on disty and vacuum system troubleshooting.

Siva283 07-10-2013 12:30 PM


Originally Posted by bmxer0122 (Post 15662228)
^That makes excellent sense! Esp since it seems to happen when it is hot out and the engine is warm. Any tips on ways to prevent this? (I will also be scouring google)

Go with what OLD4X says. He is a carb genius. I was just making a semi educated guess and bumping your thread for you

Sent from my SPH-L300 using JeepForum

bmxer0122 07-10-2013 12:37 PM

I will look into the vaccum advance/lines, replacing hte distributer cap, and possibly re-routing or insulating my fuel lines. I have the stock configuration with the line coming from the left side, under the engine then to the pump on the right then over top of the engine to the carb. In line I have a holly fuel regulator which I believe is set at 3.5 psi (had it set up and dialed in at a shop). I will also look into checking the timing.

Old4X 07-10-2013 02:30 PM

With the regulator, you are running a 2 line fuel filter, not the factory 3 line, right?

Old4X 07-10-2013 02:31 PM

You need to see what the fuel pressure is at the carb, not on the bench.

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