CJ's MJ Posted May 5, 2015 Share Posted May 5, 2015 Hi guys, I have an 89 with a 4.0 and a manual transmission. When trying to start the truck it takes several attempts to get started. It acts as if the timing is off. It will backfire through the throttle body after cranking for about 5-10 seconds after releasing the key. Normally it takes 4 maybe 5 times to get started after the long cranking. When driving it will occasionally backfire while shifting gears. Once in a while it will sputter and backfire while accelerating. To try and fix this problem I have replaced the plugs, wires, cap and rotor, a new coil and the part that coil sets in. Sorry drawing a blank on what it's called at the moment lol. I have put in a new CPS as well. I have gone through and refreshed the grounds. Is it possible a new TPS will fix it? A coworker was telling me to simply adjust the distributor by turning it to advance or retard the timing. Unfortunately that is not the solution to my problem. The Jeep distributor is fixed and is controlled electronically. At this point I just about willing to try anything to get it running smoothly. Link to comment Share on other sites More sharing options...
Marine1Texas Posted May 5, 2015 Share Posted May 5, 2015 have you did the indexing? Could be a coil putting out low voltage. Did you do the CPS advance? Link to comment Share on other sites More sharing options...
Minuit Posted May 5, 2015 Share Posted May 5, 2015 I had similar symptoms and reindexing the distributor fixed it. Backfiring and everything. After doing the indexing procedure I was baffled that it even ran. It ran like it should, in fact, except for the backfiring. Link to comment Share on other sites More sharing options...
Fernando87mj Posted May 5, 2015 Share Posted May 5, 2015 Try what they re Saying , excellent advice guys ^ , also Have you checked your fuel pressure ? Might sound dumb but you never know , Cycle the keys 5-10 times to pressurize the system and see how she starts , also if you can hook up a fuel pressure gauge and check , pressure should be 31 +/- 1 at idle and 39 +/-1 with the regulator disconnected . Link to comment Share on other sites More sharing options...
CJ's MJ Posted May 6, 2015 Author Share Posted May 6, 2015 I will try everything suggested. I will have to wait until my next day off to do it unfortunately but will give you guys an update if your suggestions worked. Thanks for the help really appreciate it. Link to comment Share on other sites More sharing options...
Megadan Posted May 6, 2015 Share Posted May 6, 2015 Try what they re Saying , excellent advice guys ^ , also Have you checked your fuel pressure ? Might sound dumb but you never know , Cycle the keys 5-10 times to pressurize the system and see how she starts , also if you can hook up a fuel pressure gauge and check , pressure should be 31 +/- 1 at idle and 39 +/-1 with the regulator disconnected . Doesn't sound dumb to me. intake backfires can be a result of lean conditions if the timing is not the culprit. IMHO I would crawl under the truck and change out the fuel filter if you have no idea when the last time it was changed was. Cheap maintenance, and can remove a potential restriction. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 7, 2015 Share Posted May 7, 2015 Change fuel filter. Test fuel pressure. Index the distributor. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now