1996 Won't Idle

96 4.0L AW4

I replaced the TPS and IAC with no results.

The jeep starts only when i hold my foot to the floor, otherwise it just cranks and cranks. It revs up fine and will even drive (two footing it). As soon as i let off the gas it sputters and stalls. Is not showing any codes.

I plan to check fuel pressure tomorrow and run the scanner on it.

any suggestions are appreciated

Job #1 is to LOAD TEST your battery. Yes, you can have a battery that is strong enough to start the vehicle but not strong enough to keep it running, SEARCH and you'll find lots of posts about it. Sure, it could be something else but you should eliminate the battery (simple stuff first) before moving on. Oh and don't forget to be sure that all battery connections are clean.

If battery checks out, then checking fuel pressure at the fuel rail (schrader valve) would make some sense. Compare your readings to factory spec.

Good luck and let us know what you find!

i'll go try it now.

billyjp2 said:

i'll go try it now.

Click to expand...

Do you have a load tester? Checking battery voltage might be inconclusive; sometimes voltage checks out but load testing fails.

I'm going to throw another battery in it in the morning. Its raining like hell right now

I don't know if this applies to your 96, but it might.

Per FSM 90--

Fuel pump receives 12v power from the B latch relay (ASD relay) bypassing the ballast resistor when the key is in the ON position, lasts about 3 seconds.

Fuel pump receives 12v power from the starter relay bypassing the ballast resistor when the key is in the START position.

Fuel pump receives 12v power from the fuel pump relay, through the ballast resistor, during normal engine operation.

Fuel pump receives 12v power from the oxygen heater relay bypassing the ballast resistor at WOT.

You do not have a ballast resistor, it was eliminated 94 models. Just curious if you are only getting power to the fuel pump at WOT, which could indicate a problem in the fuel pump relay/circuit?