Cutoff valve?

Does the XJ (1998 4.0) has a cutoff valve of sorts??? A relay or is that all handled by the CPS? I'm still trying to trace down my rare start problems.

At times I have problems with my starter and I have to get under the hood and jump the terminals on the starter. Other than that, maybe the factory alarm is malfunctioning and not allowing your engine to start. Mine does but its only when I let the jeep sit so long the battery dies and the alarm resets which automatically triggers the engine kill switch. Maybe yours is just partially malfunctioning.

What type of problem are you having? No crank, or cranks but won't fire off?

I'm glad I'm not the only one, :banghead:

I already asked about this before and I have been given advice about anything ranging from doing a tuneup (cap rotor wires plugs) through CPS TPS and every single thing (even bad ground was mentioned).

Anyways.... it happened about 5 or so times: I'm moving along in bumper to bumper traffic (any temp: varying from scorching hot day through to extreme cold, snow falling and ice and snow all around me) and engine will stall and it will not fire no matter what I do for the next 10 or 15 minutes. It will just turn but not catch and then if I let it sit, it will catch. Unfortunately it always happens where I can't get to it and see what is wrong (I'm ussually sitting in a middle of a freeway) and by the time I get AAA to dispatch a truck to pull my sorry behind from the lanes it catches and I get to wherever I am going. AFAIK there is no codes thrown, no indicator lights or anything to point a finger as to what's wrong.

The only other exception s that 2 additional times it has happened to me one time on a trail. First time I turned engine off to go and take some pics, second time it stalled (same trip). By the time I got under the hood and put on a tester (inline thing) to see if plugs are getting a spart, it started.... go figure.... I don't want to break down in a middle of nowhere and have to leave the XJ behind as it will not be an aread where you can really tow....

Kejtar

Remi....1st thing that comes to my mind id the coil....pull the coil out of the coil holder and clean the contacts.

Rev

If the engine just stalls, like someone turned the key off, then I would suspect the crank sensor. I recently had a customer come in to my shop with a 98 XJ 4.0l. It was towed in as a no start. When I turned the key to the on position, the check engine light would not turn on. The engine just cranked but wouldn't fire. So I plugged in the DRB, and I had no response from the controller. It was still under the 8/80 warranty for the PCM so I ordered one up. When I installed the PCM, it still didn't start. What I eventually found was an internally shorted crank sensor that was causing the PCM to shut itself down. The customer had come in a few times prior complaining about an intermittent stall with no codes stored. If you had a scanner that could access the start PCM start counter, you probably would see that it had been reset to 0 starts shortly after one of your no start episodes.

Long story short, if the crank sensor shorts out, the PCM will protect itself and shut down, causing the engine to stall. This will not set any codes in the PCM.

Just as a quick check, see if the check engine light will illuminate next time it won't start.

If it was my Jeep, I would replace the crank sensor.

Bryan

hmmm that's a good suggestion... now I can't remember if the check enginelight came on or not during the startup... I think it did.... in any case, you're saying that if it happens again and the check engine light doesn't come on when the key is in the appropriate positon, it's cps?

Kejtar

Kejtar said:

hmmm that's a good suggestion... now I can't remember if the check enginelight came on or not during the startup... I think it did.... in any case, you're saying that if it happens again and the check engine light doesn't come on when the key is in the appropriate positon, it's cps?

Kejtar

Click to expand...

I guess what I am saying is that if the check engine light dosn't come on it "most likely" will be a bad CPS. There are other scenarios that could cause the same condition, but I am assuming you have checked all your wiring for proper routing and for possible grounding. Check around the intake manifold for grounded wires going to your sensors. 9 times out of 10 it will be a bad CPS.

Bryan

I have to agree with Bryan on this one. For me, 4 out of 5 times when I had an intermittent starting problem it was the CPS. Once it was the coil. I found a trick you can try the next time it fails to start. Take the CPS connection and unplug and replug a few times because it is a self cleaning collector, then reconnect. Try starting. If it starts it could narrow down the CPS is bad and get it replaced.
-Mike