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CJ7 2 BBL carb problem

2K views 6 replies 4 participants last post by  BFHCS 
#1 ·
My friend has 77 CJ7 with the 4.2L. We just removed the old carb and put on a Carter 2BBL with electric choke. We also had to put on a new intake and all of that. Now the problem is that won't idle right when coming down from a high RPM. It comes down to low, below 1000 rpm. But not all the time, sometimes it will idle just fine. The fuel pump; filter and all the spark (plugs, wires, distributor) have been replaced. We think it is getting to much air and have tried to cut off as much as possible but have had no luck. Any ideas? :confused:

:usa:
 
#2 ·
Clean / rebuild the carb. They are very finicky about dirt or sediment. Not sure if I'm reading you right, but if the idle rpms are too high (and all else is adjusted), you have a vacuum leak. Plug all hoses first and see if that's the source. If not, suspect all parting lines, spray with carb cleaner or wd 40 while idling and see which seam has the leak. The liquid will alter the rpms when it's drawn into the leak. 2 piece carb can leak at seam, base of carb can leak, and especially that long intake manifold.
 
#3 ·
The carb has been cleaned right before we put it on. Its not that it idles to high, it is that it idles to low when coming down from a high rpm. Like cruz'n down the street and stoping at a light. Then it starts slowing down the rpms till it dies.
 
#4 ·
The best thing I ever did to my Carter was to tear it off the manifold and throw it as far as I could.

But as that's probably not an option, I had similar problems with it. Part of it was a vacuum leak, so definetly check on that. Follow back that nice big snakes nest of vacuum lines and try to find where one (or more) has holes burned thru them or are dry rotted. I don't know as a rebuild will help, but here's a thought.

Big problems started with mine right after I changed the fuel filter. I decided it was time for a clean filter (it had been running fine, so I should have just left it alone). Right after I changed the filte, the thing wouldn't run worth beans. Same thing, it would go okay as long as my foot was on the gas, but as soon as you let off, it would die. Turned out that I had a piece of crud in one of the jets in the carb. So as long as there was pressure behind it, it would spray the fuel. But as soon as the pressure let off, thee wasn't enough gas to keep it going, and ptooey. It would die.

A friend of my dad's, who is kind of a ******* shadetree mechanic (but a really good one, if there is such a thing), found an elegant solution. Up to now, we'd never thought of a piece of dirt in the jet. he diagnosed it as such right away, and solved it by swapping the #1 and #6 spark plugs and cranking it over. A hellacious backfire out thru the carb sent that little piece of crud FLYING into low orbit. Idled like a dream after that.

Still, the carter is garage. Go get a motorcraft carb, or a weber. At least get the conversion done to the back of it that isolates it from the computer so it will actually run partially decent.

Boots
 
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