GM7203

My 92 Cherokee is having a problem with just stalling out when driving (Intermittenly). I am wondering if the pressure regulator is not working correctly. It always starts right back up, and has no other driveability issues.
I have replaced the fuel filter, and the O2 sensor. I have searched the forum, but can't seem to find any info on the particular problem.

Thanks
Greg

97AT4x4XJ

buy/steal/borrow/make fuel pressure gauge

1976Mustang

Stealing is bad, shame on you 97AT4x4XJ. <3
lol, anyways it could be a few other things like the throttle position sensor.

tjwalker

Does this happen only when the engine is hot? Does it happen ONLY at idle or does the engine sometimes die while driving and engine is under load?

If the engine actually dies when driving, the primary suspect is the crankshaft position sensor. Yes, there certainly are other possibilities but the crank sensor is a very common failure on the Jeep 4.0 engine.

Another cause of stalling (at idle, stop lights, etc) is a marginal battery. And yes, you can have a battery strong enough to start the engine, but marginal enough so that it gives the engine management system fits at idle.

The only way to determine proper fuel delivery is with a gauge. Many parts stores will rent you this gauge free or very inexpensively. Install it on the schrader valve on the fuel rail. You should have approximately 31 psi for your 1992. Then disconnect the vacuum line leading to the fuel pressure regulator (be sure that vacuum line is pulling good vacuum!) and the fuel pressure should go up to approximately 39 psi. But if the engine dies, then starts back up again, I don't think this is a fuel pressure problem.

Good luck and keep us updated!

GM7203

It used to only happen in town at normal operating temps. Now that I have changed the water pump and thermostat this weekend it seems to be even worse, it happens on the highway now 65-70 and starts bucking like crazy until it backfires back through the intake, and then clears up until the next time. (Very intermintent)
I changed the thermostat from a 165 to the recomended 195 because it had been running rich,and the tailpipe was black and sooty. Bad thing is that it went from running about 190 to about over 210. This thing likes to run hot for some reason.
List of new parts this year are:
Radiator and hoses
Thermostat
Water pump
Plugs
Wires
Cap
Rotor
Free flow cat
Muffler
Tailpipe
O2 Sensor (Dealer recomended Delphi)
Throttle Position Sensor
Crank Shaft Position Sensor (From Jeep dealer)
Steering box
Engine rebuilt over last winter
temp sending units (one for gauge, and one for computer)
WIX oil filter
Rotella 10/40 oil
Shocks
Tires
Battery
Belt
WIX fuel filter
This is an expensive project considering I have not even got to put any toys on it like a lift or fancy wheel and tires.
Now thinking maybe coil pack or Idle Air Control. As of today it is bouncing about 300rpm at an idle.
Any more ideas on this one? I fixed this up for my 18 year old step daughter to use for work and school, so I need to get it back to reliable and safe for her with winter closing in.
Thanks guys!

tjwalker

Gotta verify fuel delivery. That is absolutely your next job. It's one of the first thing a technician would do if you took it in...

The only way to determine proper fuel delivery is with a gauge. Many parts stores will rent you this gauge free or very inexpensively.

Install it on the schrader valve on the fuel rail. You should have approximately 31 psi for your 1992. Then disconnect the vacuum line leading to the fuel pressure regulator (be sure that vacuum line is pulling good vacuum!) and the fuel pressure should go up to approximately 39 psi.

GM7203

Thanks, I forgot to mention that I did follow your suggestion yesterday. It (the gauge) was really bouncing. Best I could see was 35 to 40 didn't notice much difference with the vacuum line off the regulator. The line is new and has good vacuum. With the needle bouncing so much it was hard to get a good reading on it.