This is a 1997 Grand Cherokee Laredo, inline 6, with 160 k miles on it, 2 wheel drive, no alarm system in it

2 weeks ago, the engine was "flat" during acceleration 2 0r 3 times...a week ago, engine cut off while at red light twice on same day,,,,started back up immediately

The check engine light does come on when the car is first started and then goes off , as is normal.

At no time during these situations or when the car is driving normally does the check engine light come on

This led me to believe that it was not electrical, rather it was a fuel delivery problem.

So I dropped the tank and replaced the entire fuel pump/fuel filter/fuel regulator assembly. It ran great that day.

Note: this does not have a vacuum actuated fuel pressure regulator on the fuel rail, rather it is part of the fuel pump?fuel filter unit in the tank.

Next morning ran great, went to a job and upon leaving the car would not start on first several cranks.....finally started and ran rough, then good then rough and finally coaxed it home....

Decided to remove the Power Control Module today and took it to Auto Computer Exchange here in South Florida....they hooked it up to there computers and ran a simulator test for an hour on it and it was good....

So the PCM is not at fault according to their bench testing.

Because of the absence of any check engine light coming on after the intial start up of the engine, I am disinclined to believe I have issues with the various sensors. That is the upstream/downstream O2 sensors, the Crankshaft position sensor, etc etc.

The plugs are new, the distributor cap and rotor are good......

The fuel pump relay was switched out and still the problem.....

Any peculiar ground wire connections that might be the problem?

Any ideas?

 

my engine used to cut off at a red light as well, for me it was a crank position sensor

 

Similar problems with mine also and it was the Cranshaft Position Sensor.

 

My 95 would stuble and cut out after hitting bumps, it was the crank sensor.

 

i am not getting any engine codes to indicate sensor problems

 

Doesn't matter, neither was I or a lot of other people.

Crank sensor

 

You might also check where the fuel injector harness ground wires attach on/near the intake manifold towards the rear. There was a thread on here about that before. It was a bad connection causing random issues like you describe, that needed cleaning. Their problem went away.
It could possibly be your problem also.
I tried, but couldn't find that thread. Sorry.

 

I'v read where it's also common on the ZJ's that the plug into the ECU can cause this.

 

CP sensor on my 97 then my 03 go figure...had the exact same problem just happen to talk to another JEEP guy first before spending too much money.

(also did the plugs and fuel filter before replacing the sensor)

 

Mine did the same thing when it would get warm under the hood, was the crank sensor. I have never seen a crank sensor throw a code on a jeep before. The problem is so intermiddent that it doesn't have time to set the code.