1996 Cherokee XJ
Hi Folks,
Got a good one for you.
Story too long to explain but still a long story.

Early 2020 I had a problem with the fuel regulator.
Not holding pressure.
I could hear the Pump priming.
It got to the point that I could not start.
I had to leave the problem and travel abroad Feb. 2020.
While I was away, there was a flood at my home. (Sept. 2020)
I was not there to deal with it.
It’s parked outside.
Hell, it’s a Jeep!!
Flood was higher than the floor.
I was not worried.

Since the fuel regulator is on the Fuel Module in the tank, I was not looking forward to fixing that.
While I was away, I came up with a plan to put an external check valve on the fuel line.
In June 2021 when I got back, (don’t ask) I was able to put the external check valve just upstream of the fuel filter.
It worked!! Started up just fine. https://www.cherokeeforum.com/f2/pcm...4/#post3652483
So far so good.
I had to leave again in August.
I got back in January 2022.
I charged up the battery and started it up.
So far so good.

It is then things started happening.
First I got a P0340 code.
I cleared that.
Did not return.
Then the mystery started.
The engine is running fine.
No miss and good power.
I get a “Check Engine” light.
Codes show up.
P0132
P0135
P0141
P0138

The engine is running sweet.
Cleared codes and they returned.
I conclude it’s an intermittent problem.
I have cleaned connectors for the sensors and the PCM.
I will update after I drive the old guy.
Food for thought.

 

Have you tried cleaning the grounds?

 

Not yet but that's a big job.
Where do you start?

 

Based on the codes, the problem is either the O2 sensors or the wiring to them. (Bad grounds could also cause it).

 

I got a new one for you.
Codes have been cleared and do not return while running at home.
Will take it out for a spin today.
It is starting and idling fine and no miss.
However, when I open the driver’s door while idling the “key in ignition” buzzer sounds as expected, the courtesy light comes on but…
The engine splutters and dies.
Confirmed it many times.
Any ideas?

 

So next to the door, there is that button that senses if the door is closed. If that is pressed, and the door is open, does it still happen?

 

That is the first step in isolating the cause. That's the easy part.
Got to get hold of some tape.
The "Key in ignition" buzzer will be the tricky one.

 

The key in the ignition buzzer only sounds if the door is open, which will not buzz if you tape the door button. I am a bit confused on what exactly you meant, so please clarify why the key in the ignition buzzer will be tricky.

 

Two things happen when the door is opened while the engine is running.
The light comes on and the buzzer sounds.
The buzzer sounds any time the door is opened and the key is in the ignition switch.

 

The check valve in the fuel line scares me.

 

Why?
It's working.
Remember, the pressure regulator is in the tank.
The fuel lines are made to hold the pressure.
That might not work on your model.
In any event, your pressure regulator is on the fuel rail.

 

There have been several reports I've seen of people using check valves and catching their jeeps on fire because of it.

See post #13. He was a lucky one:
https://www.cherokeeforum.com/f2/fue...k-valve-21921/

 

I would not recommend the use of an external check valve for models with the pressure regulator on the fuel rail.
The '96 was designed with the regulator in the tank and the fuel lines were made to take the pressure.
With the regulator on the rail, the high pressure is confined to the rail.
I believe the check valve in the pressure regulator is the key and when there is a leak down of pressure, the regulator can be easily replaced on the rail.

 

What happens if you turn the switch to turn on the interior lights without opening the door? Or turn the headlights on? Thinking a poor ground could be made worse turning on lighting that's grounded through the body.

 

I will look into that.
Never thought of that.