4.oL ZJ start issues

[JackstandJohnny]

so, bought another ZJ today, and on my way home decided to take it to the car wash and clean off the crud. and of course when i was done, jeep wouldn't start. so heres whats going on. it cranks over fine, just doesn't want to catch and start. i did not wash the engine compartment. also replced distributor cap just incase. it was dry. when turn the key i can hear the fuel pump whirring in the trunk, and there is fuel in the fuel rails, or there is pressure in the rails. i knwo it is also getting air. plugs and wires also look relatively new also replaced 6months ago. also ran the codes and got a code 55. so heres where i'm sitting: engines cranking, its getting air, seems like its getting fuel, and spark i'm not 100% sure on as i haven't tested all the wires and plugs yet. keep in mind, it ran and started great all day, until i washed it, then it died. i want to know what the connection is dammit lol.
need to get this fixed. this is supposed to be my DD
thanks

John

[ibyers1]

CPS or coil.

Cracked coil + carwash (lots of humidity) = bad coil

I think your next door neighbour can give you a hand if need be.

[dunl]

If it's not the coil, PM me about replacing the capacitors in the PCM unit. I had to do this to my previous ZJ with the same issues as yours, and a new coil didn't do anything.

PM me, in case I miss it.

[JackstandJohnny]

ok. checked for spark today, and nothing. so i'm leaning towards, ignition coil. might change it out this weekend. and if nothing, then dunl, perhaps its in the pcm.  for sure i will PM you.  thanks for the idea dunl.

 haha, thanks ian!

[ibyers1]

It might also be the CPS. After three seconds if the PCM does not receive an input signal from Cam & Crank sensors, then the PCM will not allow the coil to fire or permit battery to the injectors

[Jack's Jeep]

Sounds similar to a problem I had with my Cherokee.  In the end it was my battery.  Mine would turn over but not catch and when it did I had to keep it revving untill it warmed up a little.  I thought I might have water in my tank or dirty fuel injectors.  A lot of people did think it might be sparks coil rotor, all that stuff but I had just gotten a tune up replacing all that.  In the end the battery completely gave out, (after my jeep got rained on all day), when I replaced it I haven't had the problem at all.  

Battery was 8 years old.
Starts in the minus stupid now without a problem.  And in the rain.

Good luck.

[JackstandJohnny]

hmm, i checked teh battery today, and it was holding a charge of 12.5, so i think its ok.... as for my dilemma, update: pulled the ignition coil today, tested it with an ohmmeter and it was reading between 3 and 5, so i think the coil is fine.  i'm now leaning towards crank position sensor... not looking forward to replacing that. anyone have any tips on how to do this with ease? any tips would be appreciated

[dunl]

I'll start looking for that link for the PCM capacitors.....had trouble finding it the other day.

[dunl]

Post #27, halfway down.

http://www.jeepforum.com/forum/showthread.php?t=463586&page=2

No pictures, but this is what a capacitor looks like in case you're not electronically minded....



These are the ones you are looking for, go to an electronics shop and find them - that's the hardest part. 220uF 25V

I remember that it didn't matter which it was for one of the numbers.....the 25v I think....but hopefully an electrician can jump in here and confirm that.

Pull the PCM, dig in the gel, find the capacitors, remove and resolder.

Maybe do some searching around and see if you can find the thread with the pictures....there IS one out there somewhere. I'll keep looking too.

[dunl]

WOWZIES!!!

A few beer, and I rule!!!!

Here you go....pictures on second page.

http://www.jeepforum.com/forum/showthread.php?t=330109

Like they say, might not be your problem, but might fix it for you.  I was thinking it was the CPS for me as well.....

[JackstandJohnny]

that thread has a whole bunch of cool information.  did you change out the capacitors, or did you bring it into a computer shop?

[dunl]

Took it out, heated up the capacitor arms on the board, and pulled them out a little bit on each side, back and forth, back and forth, until they were free.  Then put new ones in and resoldered. Make sure you pay attention to which way is the positive side, and which is negative. Mark it down on paper - you'll regret it if you get all the way through only to find out they were backwards.

30 minute job if you have everything.

I don't do electronics, but it wasn't rocket science. Only thing I would do is find some way to resealup those capacitors...silicone or something, so water doesn't get in, which I didn't do.

cLAY - I MENTIONED THIS TO YOU WHEN YOU BOUGHT IT, BUT IT WOULD BE A GOOD THING TO REMIND YOU JUST IN CASE.....PULL THAT PCM AND RESEAL IT UP BEFORE YOU GO WADING WITH THE ZJ.

[cLAY]

Ya thanks, I was running wiring on it last month and noticed it and it jogged my memory.

[jpthing]

hmm, i checked teh battery today, and it was holding a charge of 12.5, so i think its ok.... as for my dilemma, update: pulled the ignition coil today, tested it with an ohmmeter and it was reading between 3 and 5, so i think the coil is fine.  i'm now leaning towards crank position sensor... not looking forward to replacing that. anyone have any tips on how to do this with ease? any tips would be appreciated

It's actually prettyeasy...2 small (10mm?) bolts, one rubber cover and one electrical plug. It's just a little hard to get at....I did one on a XJ from under, tricky but not too bad unless you're a beefcake (big arms) and I reckon it could be acsessed from under the hood too, if you're a bit of a contortionist...I think it could be done in 15 minutes but 1 hr fer sure!

I have since started carrying a spareCPS on the trail....

[JackstandJohnny]

haha,  funny you say beefcake. i'm definitely not small. (300 lb aren't the most agile of people usually)  so i'm jacking the front end up, gonna crawl under and just unbolt it, hopefully