Starts & runs for 4 seconds = Ignition and engine dynamics are OK.
The quitting after only 4 seconds is indicative of a loss of fuel supply provided initially by the accelerator pump in your carb during the start process.
So looks like you need to focus on fuel supply. Rather then ask for dozen of suggestions where to look from our members why not use the factory manual's troubleshooting chapter to perform an organized and well documented investigation into your problem?
In the case of your CJ3B the factory manual would be either SM-1002 (early) or SM-1046 (late).
The best part of the Fuel TS'g charts for your case is the third section. The only section of the engine TS'g charts that may help are the "Lack of Power" topics. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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