Bobberfishin

My son's 1999 Cherokee Sport has just stared giving him fits.
It will start up w/ no problems, but if you were to drive around then turn off the jeep (as if you went into a store for a few minutes) & try to start it up it will crank but no start.
Cranking is not a problem, but it's not getting fuel (or flooding)? It will take a few minutes to start back up.
Could something be heating up and separating when it gets hot, and when you try to start it again it hasn't reset (or cooled down) to get back into position. Could the fuel pump be losing pressure after warming up? It runs fine whether it's when first starting up or after finally getting started after turning off.
1999 Cherokee Sport, 4.0, auto transmission, 130,000 miles, it does not have 4wd
Any help is greatly appreciated, Thanks.....Bob

rnmcguire

It's probably the well known "Heat Soak" issue also known as vapor lock. Basically the exhaust manifold radiates heat up to the fuel injectors and causes the fuel inside to vaporize. I'm dealing with the same issue now that it's warm outside. I went to the dealer and got an insulating sleeve today and plan on installing tomorrow over the fuel injector. Here's another thread that talks about this issue.
https://www.cherokeeforum.com/f2/jee...t-soak-117056/


From my experience a fuel pump usually causes problems on cold starts because it's had time to lose pressure. Each time I had a fuel pump problem a hot restart was never an issue.

DFlintstone

That^ and the CPS is known for failing hot, and random stalls. I hear sometimes a bad CPS can make the gauges act goofy Btw. I'd check for spark with the coil wire. (while its not starting)(holding it with 1/8 inch to ground). Should be a crisp snap. Others might pull a plug, and hold it grounded to lessen the chance of getting zapped. An easy way to see if it's a lack of fuel is to give it a little shot of starting fluid and see if it fires.

Having your codes read might help as well.

Bobberfishin

Spoke w/ 2 different mechanics & both said it was unlikely to be vapor lock.
They said vapor lock had not been an issue on 1999 Cherokees' & had been addressed by then. Didn't say it couldn't be, but unlikely.
Put the diagnostic computer to it & .........
Turned out to be a faulty Temperature Sensor. Would not relay proper temp to "brain" so injectors would be getting way too much fuel.
$55 part