My 99, 4.0 auto, 4x4 Starts great, after a short drive, and shut off, I have to press the pedal to the floor to start it again. I pulled to fuel rail, and checked the injectors for leakage, no apparent leaks. Fuel pressure is 48psi, and holds for 30min. Jeep seems to run fine, other than secondary hot start.
Any ideas?

 

Both of my xj 4 liters do this too (89 and 97). I've just kind of dealt with it but I would like to know too...

 

Heat shield?

 

Up until recently, there had never been a issue. Jeep is bone stock

 

Mine does that to, I read somewhere that they all do that because of the way the injectors are positioned. When it is off and the gas is not moving threw the injectors the remaining gas inside them is evaporated because of the heat. The hard starting is because they have no gas to shoot into the engine.

 

Mine only recently started doing this.

 

Any other ideas?

 

Does it do it all the time after it been warmed up and once it warmed up does it show another weird or different problems while driving?

 

Every morning, I can turn the key and it will start right up. Then if I drive it 2 miles and turn it off, I need to floor it, to start it. Other than that, runs as normal.

 

any codes?
someone with more experience hopefully will chime in.
after only driving for 2 miles,& with your average temps,it is not heat soak.
so the heat shield is not a issue now.
you have a fuel issue. check for codes, test the injectors. do a search here for info on how to perform the test.

 

Cam position sensor under the dist. cap. Mine was doing this as I have stated on other threads, ended up replacing the crank sensor, twice, finally with OEM from dealer. With 2 autosone cam sensors, same thing, idle was crud and started hard like you say after warmed up, long cranks. After a week it finally set code 54 and I could not believe that 2 brand new dontalast cam sensors were bad, was ready to replace timing chain. The original problem was likely the fuel pump and regulator that I and you replaced. On a last chance whim I threw the original cam sensor back in this morning, with 200k on it, and whadda ya think. Starts and runs like new even tho the sensor part was completely broken from the big plastic circle. Soo rellieved, had been hunting this problem for weeks. I'll be getting a genuine Mopar to make that perm. I drove about 100 mi today all start and stop doing service work, no problems, at all. Otherwise Ida been fighting it the whole way.

 

I pulled to fuel rail, and checked the injectors for leakage, no apparent leaks. Fuel pressure is 48psi, and holds for 30min.

 

Yeah, I kinda leaning towards it being a sensor/electrical issue.

 

If I held down the pedal, after about 15 cranks it would start and the CEL would come on too, code 54 'no signal from cam sensor while cranking'. The sensor was about 4 months old, as I say I put the original 200k mile sensor back in and that did it. Mopar PCM's like mopar sensors.

 

I was going to say cam sensor also that's what it sounds like. But it would also try to die while driving also.
Try is on a cold start get a heat gun or blow dryer and heat up that area like a normal drive then try to start it. If it it that it shouldn't start till it cools off. If it does start let it warm up and shut if off or drive it like a normal day, check rail pressure again and spark at each plug for spark.