1991 Jeep Wrangler Q&A

1991 Jeep Wrangler Question: hard starting then backfires when driving

155000 miles, ran fine until it started too backfire when driving and now hard starting. changed fuel filter, and new spark plugs,wires,rotor and cap. -
Answer 1
Sounds like timing chain worn out and possibly jumped a tooth. and/or possible valve problem. Do you know how to check either of these? Do you have a vacuum guage? Have you inspected plugs yet to see if it's only one cyl. being affected or all? I know you said you replaced them , but that will give you some useful info. Reply to this if you want more tips. Good luck. I also noticed a tip below my response that mentions common problem with TPS. Best get proper diagnosis first before wasting money on parts. -
Comment 1
am starting with vac lines replacement since their look to be org ones. then looking at dist. since it is org. then going to timing chain. do you think it could be fuel pump? Thanks for the feedback -
Comment 2
If you can test the throttle position sensor that might save a lot of time and money. A dead spot(s) in that can cause those symptoms. Did you see the mention of 'repairpals. feedback regarding that and those jeeps? -
Comment 3
Going that way now also pull gas tank found split gas line from pump to outlet connection line. filter was no good also. Look like I need to start one end and work to other end. Thank again -
Related Items:
The throttle position sensor (TPS) may fail causing intermittent drivability problems like hard starting, stalling, and/or hesitation when accelerating. A failed TPS will require replacement, p...