hard to restart when warm

My 98 4.0L is very hard to start after I have shut it down and it sits for a few minutes. It just turns over and over and stumbles a little, but won't catch. Then on the second try it fires right up.
Its been doing this for awhile, but recently its getting harder to start.
It always starts right up when cold, and immediatly again after turning it off. But at fully warm temp, and a wait of 20 minutes or so...its a bear to get started again.

Any ideas?
Any cures?

Thanks.

Fuel pump?

Hi 'nutz -

I'm no expert, but I have a similar problem and talked with a Jeep mechanic. He said he thought it was the fuel pump. When warmed up, there's a valve in there that holds the pressure when the engine is stopped. That valve on mine is shot, so the pressurized fuel leaks back in the tank.

To see if this is the case for you, try turning on the key (don't start it), turning off the key, then try to start it normally. This will let the fuel pump build up pressure in the fuel line by priming it twice. This works for me every time.

Hope this helps!

Cheers -- Greg

IIRC, there is a TSB on this issue. Do a search for "heat soak"