91 Jeep Cherokee wont stay running

91 Jeep Cherokee wont stay running.Fuel pump has been replaced, all vacuums check , EGR , map sensor , relay , hose to the map. My husband has been spending 2 days on this and you know I feel really really bad for him. Seeing that he can do anything and fix anything mechanical . But , he is stumped. He states that up starting he can hear the fuel pump then it just stops. He has replaced 2 thinking the first was bad. Sad thing about this is I need this vehicle. I work in surgery and for 5 docs and I am out of a vehicle. Help in Michigan.

In my '89, '92, & '98, (all 4.0L engines), the fuel pumps do the same. They only run for a moment to pressurize the fuel lines and rail that connects to the fuel injectors. But, this is in the 'ON' position only, before starting the engine(s).

For helps sake, what size is the engine? How long does it run, under what circumstances? And what else has been done within the last several thousand miles from a maintenance stand point? i.e.- A tune-up,(spark plugs, wires, cap & rotor, battery, batt. terminals & cables?- etc...??)

The various sensors can be a rather twisted river to navigate, and can certainly cause your described issue. I'll direct you to some good info on said sensors. And remember to remind your dilligent husband that his efforts are appreciated! lol!

~good luck!

-Look at the 'TPS'-(Throttle Position Sensor) and the 'CPS'-(Crankshaft Position Sensor) Sections. (In some instances, unplugging/cleaning/and replugging the sensor(s) connections can temporarily fix some conditions) This is not a proper repair!

I had an issue with my '89, where it would not run/stay running (it constantly stalled). It turned out to be the IAC (Idle Air Controller). I got another from the junk yard for a couple of $'s. It's run fine ever since!

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

As an extra bit of homework, use the 'search this forum' tab at the top right of the page, just under the page #'s. You can also use the 'Advanced Search' option to further filter the results... Just type in "no start" or "hard start" to find other posts with similar issues/results.

Thanks for the helpful information.The engine size is straight 6-282 or 292?.It has had no recent tune ups on it. I just parked it at a gas station one day,came out to back up and it stalled.You can start it just fine but it runs for 1-3 seconds and rpms drop and it stall. When I did start it at one point to get it out of our garage so the studebaker could be back in.I nailed the gas it went but stalled.He did replace the auto shutdown relay,but when he tested the ports?there was no volts registering in port in the distribution box.?The fuel pump will come on but as soon as the engine starts the pump will quit running.After it stalls then the pump will come back on again. If the key is turned on 2-3 x's we can not get crap for pressure and the it leaks down right away.The relay can be taken out and the fuel pressure is good/Could this be a camshaft position sensor he has done the cps already.Thanks, Marcy.

I don't know how the CPS might affect the fuel pressure or various relays...

Perhaps some other, more knowledgable, person might chime in on this subject??? Anyone?
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From the link I posted, about the CPS: "This is the BIG Kahuna of problems for people with no start, hard to start & stall out issues!"

Again, I could have sworn up and down that my CPS was causing the same problems in my '89, but alas, it was only the IAC. (It's two torx screws, and a wire harness to take off. Just next to the TPS on the throttle body.)
With mine, the 'nipple' was stuck open/extended causing no air to get into the engine at closed throttle. This effectively chokes the engine causing stall-outs etc...
If you take the IAC out, or can manually keep the throttle open a bit, and it stays running, this is probably the culprit. Lack of air.

If not, go on to testing the voltages on the CPS and see if it needs to be replaced.