Originally Posted by doug80cj5
I have a 1980 cj5 with 304 that will start up run but then dies after 20 seconds. When running it will be smooth a few seconds and then run rough as hell and die. Was running fine till last week when I drove to the store and it would hesitate when trying to go over 2500 rpm and on the way back I could barely keep it running. Two months ago I had some electrical issues and had to replace coil, distributor(aftermarket Mallory with no vacuum line), ECM etc.. so I don't think its electrical because it ran perfect since. Fuel pressure is good with newer pump/filter. I can see it squirting pretty good gas into the carb but still wonder if I needs a rebuild or something is up with the auto choke(its open when trying to start). The last time it ran great I was hot rodding it around town pretty good so I guess I could have jumped timing or stretched the chain.. I'm going borrow a timing light and check this weekend. Hoping somebody has been through this before and has advice because I'm tired of spending more time under the hood then on the trails. Thanks in advance.
Timing light will show if there's any ignition problem. If it's flickering all over the place doing weird stuff, then there you go. You could check every plug cable easy enough.
You could have some debris in the carb. Doesn't take much. Or maybe good fuel pressure overcoming a worn/leaky needle valve.
Something is up with the choke, needs attention.