Engine Hickup/Stumble? Fuel pump... TPS... CPS????

Its an 88XJ 4.0 AW4 with 160k on the Body and 30k on the Engine

Heres what I have been expirienceing, maybe its a sensor (TPS, CPS, or other?) and I am just miss diagnossing it, but I have attributed it to a bad fuel pump.

Here is whats happeneing: For a long time, every time you start the jeep, it starts up fine, then you put it in drive and back out of my driveway, and immediately when the RPMs drop to idle (between auto gear change, or if you just let of the gas) engine would die. Recently this problem seems to have gotten worse, and another one has arose. After getting it going, while semi warm, trying to drive around around 1000-2000 RPMs sometimes, not always, theres a huge stumble, but put it in nuetral and Rev it to about 3500 a couple times, and drop it back in gear and it seems to be doing fine. It runs fine 90%... maybe even more or the time, and cruises down the highway at 2200 just fine.



Anyone have any ideas or pointers? I think I asked about 3 or 4 questions. Please Help me out or let me know if you have had any similar problems or expiriences.

-Tim

I had a whole bunch of stuff going on in my 88, every one I addressed, seem to help some.
Some of the stuff that seemed to help the most, were a O2 sensor, seemed to do away with a stumble at around 2000 RPM.
EGR had a weak spring (opened a bit too easy), really messed with low RPM operation.
EGR tansducer was leaking vacuum.
Setting up the TPS to near Jneary´s specifications, helped the motor become quit a bit more zippy.
Cleaned all grounds and connectors
Think I finally found all/most of the vacuum leaks.
General service, filters and tune up.
Throttle body cleaning, Idle motor passeges and piston.

I also suspected a fuel pressure problem, drove around with a fuel pressure gauge, zip tied to the windshield wiper, for a couple of days, no problem there.

Tim88XJ said:

Its an 88XJ 4.0 AW4 with 160k on the Body and 30k on the Engine

Heres what I have been expirienceing, maybe its a sensor (TPS, CPS, or other?) and I am just miss diagnosing it, but I have attributed it to a bad fuel pump.

Click to expand...

The stumbling and stalling symptoms sound typical of a bad CPS. If you haven't replaced it in a very long time, now's a good time to do it. Eventually the CPS will become so bad that the engine will take a long time to start and when it eventually does, it'll die every few hundred meters, potentially leaving you stranded in the middle of nowhere.

I put a six pack on a bad TPS.