trouble starting when engine is warm
 

i have a 96 cherokee and its recently started having trouble starting. if i leave in turned off all night, then go to start it in the morning, it will start up fine. then, if i turn it off, and then come to start it back up in about 15 mins, it will turn over and turn over for about 15 seconds, and then finally start up, but sputters, then revs to about 2500rpms, then goes beck to normal idle. while im trying to start it, i will pump the gas a couple times. my friend told me to purge the fuel rail, thats what fixed his.i have searched on here and cant find out how to purge it. i dont know if its the spark plugs, the fuel filter, air in the fuel line, or my fuel pump. :brickwall:

please some one tell me what you think is wrong with it. i dont want to replace something thst dont need replacing. money is tight.

Sounds like a timing issue - did you do any tune-ups lately to include the plugs, wires, coils, or distributor?

no i havent done any lately. it all started the day my brakes were sticking, last friday

The reving is a by-product of gas in the chaimber when starting. It is the initial starting that sounds like a problem - I would do this first. Take your plugs out and re-gap them. Make sure they are at .035 for optimal spark. While you are in there check the cables and make sure they are still good - check for freyed coatings and look in them to make sure the clips are not worn out.

Next pull the distributor cap off and make sure the rotor is not all eat up. Then check in the Cap and make sure it looks pretty good and not carboned up.

alright. so you dont think it is anything to do with the fuel?

I dont think so given that when you do leave it all night it fires right up. Sounds like a spark prollem. maybe when you heat the engine up the plug wires get all lose and bad connection is made. I would start with the ignition system (your spark)

Search "Starting when warm" and you will find all kinds of posts that are similar to yours. It will help out.

alrite ill try that. i will reply and let you know what fixes it

Your issues could possibly be caused by a bad check valve in the fuel pump. What you can do is rent a fuel pressure test kit from Auto Zone or maybe another local parts store. Hook up the fuel gauge to the fuel rail and let it idle for a few minutes, then shut off the Jeep and leave the fuel gauge hooked up. If your fuel pressure drops more than 20 psi in the next 30 minutes your check valve is bad in the fuel pump, meaning you need a new fuel pump. Since you have a 96 you may need an adapter to hook up to the test port on the fuel rail which should come in the kit. I would also pick up a Chilton or Haynes if you have the money. It will give you the specific fuel pressure ranges for your year. This procedure is really a lot easier than it sounds, I just did it yesterday.

Sorry I'm looking at my Haynes and your system may be totally different, if you have the TBI system than your test port is on the throttle body, and I don't even know if the test I stated is relevant to your vehicle. 96 and later models are different than mine.

i have narrowed it down to the CPS. the cps is also the cause of bad gas mileage and power loss. i checked the distributor and its fine, i had to take off 3 plug wires from the cap to get the cap off to look inside of it, and mis-numbered the plugs. i started it up and it was sputtering and missing...after thinkin everything over, i had misplaced 2 of the plug wires. so i switched them, and its back to normal. i also unpluged the cps and started it up, then turned it off and plugged it back up. seems to work fine now, it will start up on the first crank. im still gonna get a cps off my buddies jeep that he is parting out. same thing happened with my a/c clutch relay. my check engine light will come on and i will get my haynes manual and and check the code its calling for. i will take the relay off, then put it back on and the check engine light will go off for a day or 2, then come back on. so i repeat the seteps and it goes back off for a couple days. i know whats wrong with it i just havent bought it haha