94 Jeep Grand Cherokee 4.0 Start Up Problems

[lowside]

My Grand Cherokee started acting up this morning. It wont start during cranking but when I step on the gas it will run for 2-3 seconds then shut off like its out gas. When I turn the key I can hear the fuel pump prime but it wont start unless I press the gas pedal.I replaced the fuel pump about a year ago. I was wondering if anyone had any ideas.

[jdl]

Use a gage and check fuel pressure. Some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. Any applicable mil codes? You may need to clean the throttle-body and check idle air.

[fredjacksonsan]

Could be the throttle position sensor. Also, check the regular Cherokee section, there's a "how to" section that may be of help.

[lowside]

Problem solved!
When I went back to run some tests it would not start at all, nor could I hear the fuel pump priming at this point I was directed to check for trouble codes by keying the ignition switch on/off/on/off/on and there was no check engine light but after a while I had a security light that stayed on. The security light lit in the on position and not flashing, means that there was a loss of communication with pcm and I noticed that the auto climate controls digital display weren't reading out as well. luckily, I was able to find a used one dirt cheap for my Jeep as they have several different types and mine had no identifying numbers on it. After swapping the pcm out it ran a little rough at first because the pcm had to relearn the engine sensor inputs but its fine and the starting problem is gone now.

Thanks for all the input as it was useful, because I really want to keep this Jeep, it has 200,000 miles on it and still starts right up with no hesitation and still runs/drives great, in fact the thing runs like it can easily repeat.

[fredjacksonsan]

Right on! Nice catch. The PCM rarely goes bad IME.