75 cj5 back fire and rough idle

I recently bought my first jeep a 75 cj5 it ran good for afew months and then started to backfire when decelerating and idle rough?

 

Hi

I had the same symptom a while ago.

Check anything fuel-related. It turned out I had rust in the fuel tank, and it ate all the lines, contaminating fuel pump, fuel filter, carb, etc.

It did cost a few $$$ to make it work, but now it runs sweet



Bob in Sherbrooke, Province of Québec

 

My 75 has had backfire issues off and on in the past and has always been a bad doughnut gasket - rough ride causes the bolts to work loose and the gasket to wear.

 

probably fuel related, but could also be caused by poor connections on the ignition module, located on the p-s fender. the breakerless induction discharge (b.i.d.) distributor is really poor. you can swap it out and get rid of the ignition module by converting to pertronix or hei distributors.

 

258?

 

A faulty or disconnected diverter valve will cause a mean backfire when decelerating. Used to happen on my 304 all the time until I hooked it up. The rough idle might be semi-related to the backfire. I'd check for a vacuum leak. Really need more info to diagnose further.

 

its a 258 with carter carb and I replaced the doughnut and didnt help

 

wore out carb? common on the carters.

 

How does the engine run while heavily accelerating or while maintaining throttle at cruising speeds? Any hesitations?