Need help diagnosing slow/no start. Wifes ZJ

[SpeedyVic]

Here is the situation:

On our ZJ, when I try to start it for the first time for the day, I have to turn the key on for a little while before I can get it to start. While I leave the key on, I can hear a clicking noise coming from the ASD relay. It will first start clicking fast and then gradually slow down (like presure is building up somewhere) and then come to a stop. I can then start the Jeep. On some colder days, it will click longer or sometimes not click at all. If I do not hear the clicks, it will not start.

I have changed the relay, the cam position sensor, and replaced the fuel filter. I am about to replace the fuel pump next, but am not quite sure that will fix it. If it does not click, I do not get any spark from the coil, therfore no start. It has something to do with the Auto Shut Down relay.

Anyone have any ideas? I do have an after market alarm installed and have heard that this MAY have something to do with it. But why would it act diferently in diferent temperatures if it is the alarm?

 

[spencurai]

this may sound cheezy but my wife's 99 xj was doing this....it turned out to be a bad battery....

 

[SpeedyVic]

NEver even thought of the damn battery! Spence, did your wifes XJ do th clickety-click thing as well?

 

[spencurai]

it would click and click and then all the instruments would go dead, not even the radio would turn on...it would go from fully firing to fully DEAD in the turn of a key..I think the battery was shorting out or something crazy. It was a lease buyback that sat on a lot for a long time with the battery absolutely dead so I had a turd of a battery to begin with.

I got an optima red top on loan from jamesgeologist on here and now it works great!!

no clickety!!

 

[Herzog]

Yep. I second the bad battery.

I bet one of the cells in the battery went bad, just not having a enough cold cranks to start it, but everything else will seem to work fine.

 

[Cody]

bad relay? I had an electrical demon from hell about a year ago and we finally traced it down to a bad relay. It wasn't doing the same things that you are describing, but I see relays go bad at least once a week and they can do some weird things.

Cody

 

[SAMI]

i vote battery. my buddy's 95 cherokee did this exact same thing at work a year ago. it ended up that he just needed a new battery.

 

[SpeedyVic]

Ok, I checked the battery and all looks well. I get the clicking noise when I turn the key to on, but not all the way to start. It is clicking from the relay and the fuel tank. If it is cold, it will not click right off the bat, but I do not get any spark. The fuel pump does not come on until I get the clicking.

I have replaced the ASD relay, and the fuel pump relay. Still clicks. This thing is driving me nuts! I can't figure it out. I am tired of replacing things for nothing.

Anyone want to buy a ZJ? Runs good! (if you can get it started)

 

[mbryson]

I had a similar nightmare on my XJ last fall......I bought a DEALER CPS after spending about $1000 on misdiagnosis and other parts and everything's been cool since......Where did you get your CPS? (my junk 'new' one was from Autozone.....no more electrical parts for me from there)

 

[SpeedyVic]

I got a Mopar Cam sensor from my dealer. Could I also need to replace the crank shaft position sensor? I thought that the CKS was only referenced while the engine was running.

Yesterday, as it began to click, I quickly dico'ed the CPS and reconnected it. The relay clicked the whole time. So I THINK I can eliminate the CPS. So that SHOULD leave me with the PCM, fuel pump, and possibly the CKS. If I have left anything out, please let me know.

When I get home from work, today, I am going to swap out the batteries between my YJ and ZJ, just to be safe.

 

[mbryson]

Originally posted by SpeedyVic
I got a Mopar Cam sensor from my dealer. Could I also need to replace the crank shaft position sensor? I thought that the CKS was only referenced while the engine was running.

Yesterday, as it began to click, I quickly dico'ed the CPS and reconnected it. The relay clicked the whole time. So I THINK I can eliminate the CPS. So that SHOULD leave me with the PCM, fuel pump, and possibly the CKS. If I have left anything out, please let me know.

When I get home from work, today, I am going to swap out the batteries between my YJ and ZJ, just to be safe.

Just to verify (now's a good time), I'm assuming you have a 6 cyl.

 

[Milner]

The fuel pump pressure valve could be leaking down, causing the relay to click until pressure comes back up. I know on XJ's the fuel pumps have valve that holds pressure in the line for the next start, this valvle often goes bad in an otherwise good pump.
Causing it to have to turn over for a while to build pressure before it will start.

You should have a check valve on the fuel rail, get a guage and test if the pressure stays in the line.

 

[spiderman]

I agree with this guy. A lot of older gm's did this, same thing. if you want a quick way to tell, the fuel pump should run with the key in the on position, so just let it sit in the on position for a few seconds, allowing the pump to pressurize your system. then try to start it.

 

[SpeedyVic]

Marc, I have a 5.2 V8.

I agree with this guy. A lot of older gm's did this, same thing. if you want a quick way to tell, the fuel pump should run with the key in the on position, so just let it sit in the on position for a few seconds, allowing the pump to pressurize your system. then try to start it.

That is what I have been doing, except that on really cold days, it never clicks and the thing will never start.

Does anyone know what conditions must be met before the PCM will engage the Auto Shut Down relay, and allow for a spark from the coil? Does it monitor the fuel presure? Remember, I will not get a spark if the clicking does not go its full course. The click seems to be directly related to the fuel pump (I can sometimes hear an accompanying click from the tank) and sounds as if it is related to pressure (slows down as if being pressurized).

My worry is that I will change the fuel pump (quoted @ $250 from NAPA) only to find out it was a symptom of something else and not the cause.

I really appreciate all the help so far, guys. Keep it coming. I know that we can get to the root cause eventually. I like this vehicle, but I am just about ready to push it over a cliff!

 

[SpeedyVic]

Update: It is definitely not the battery. The click is definitely coming from the ASD relay, but it is definitely not the relay that is the problem.

What else am I missing?

Note: Kim (my wife) is offering a case of beer to anyone that can lead us to the source of the problem. If you don't drink beer...well, I'm sure we can find at least one redeeming quality about you!

 

[Cody]

well, I would probably start in teh power dist. center under the hood, check all the fuses and test the relays, then take the bottom out of the glove box and start checking relays in there. I had a major electrical demon that was traced to a relay in the glove box. I took it out and havn't replaced it and havn't had any other problems. I hope it wasn't too critical.

Cody