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grg_hbbs 08-24-2010 06:46 PM

Yj wont start...Please Help
Im sorry if this has already been posted but i really need help. Ive exausted everything on this jeep. I know the problem im having is related to ignition and on top of that i know the problem im having is because im not getting any spark. The list of everything ive replaced is as follows
plugs, wires, cap, rotor, coil, ignition control module, crankshaft position sensor, injector, fuel filter vaccuum lines. after all this i checked with an inline spark plug checker and found out im not getting any spark. if anyone has had related problems and has solved them, id really love your help. Thanks in advance.

Fweaky 08-24-2010 08:26 PM

I'm not much on electrical but check your wiring around where it plugs into the ECM and also any exposed wires around your distributor. I have had wire damage cause the same problem in both areas. Also check your plug connections at the ECM. I believe the hot wire that comes from the ignition switch to the ECM is red and white. Hopefully someone else can be clearer with a solution.

grg_hbbs 08-24-2010 09:50 PM

thanks for such a quick response. I went out and looked for exposed wires and didnt see any but i check more in depth tomorrow. Also forgot to mention i also put in a new ecm as i heard that sometimes causes that problem. is there anything im sopposed to do with a new ecm? ive heard something about a hard reset but didnt know what it meant. Also does anyone know if there are any relays that would cause the problem? If so where are they hiding. ive had a similar problem before in a 94 honda accord and it turned out to be a relay. again any help would be appreciated, kinda driving myself crazy trying to figure this out.

UABYJ94 08-24-2010 10:58 PM

What year jeep what motor and auto or manual?
If you have a meter then ohm out your CPS to verify it is working.. Follow the wires up to the harness making sure they aren't frayed or burnt or even broken.. Then make sure your battery connections are clean and tight. Check where the grounds on the firewall and make sure they are making a good connection.
My 94 2.5l did this awhile back and turns out I hadn't tightened my ground back on the battery. It was getting enough contact to feed the starter but nothing to the ECM.
Check your coil to see if you are getting fire to the line side,if so, check the dizzy side..
I'll check back in the morning to see what you found..

grg_hbbs 08-25-2010 08:25 AM

Its a 1990 wrangler yj 2.5l 4cyl 5 Speed. 12 volts at the coil, do i check the dizzy while cranking or cold? got an in line checker set to gap yesterday but and still no spark. Checked all grounds and they seem pretty good, but how many are there. found two on the firewall and one on the engine. looks like there used to be one by the floor on the drivers side under the clutch inside the cabin but its broken at the clip and i cant seem to find the wire. Is that an important ground or is there a reason its cut? also while down there found two yellow wires that go nowhere. cant seem to find where they would plug in there just hanging down under the stereo. anyone know what there for or where they plug in? Thanks again for the responses.

UABYJ94 08-25-2010 08:52 AM

That one inside the cab sound like the fuel pump ground. Should be a blk/yellow,IIRC.
Our YJs came with different packages but for the most part used the same harness even on those without the extra options. You may find plugs and wires hanging that were for options yours didn't come with.
If you have power at the coil then your ECM is good. Check for output voltage on the coil,, you may have bought a bad coil out of the box. Seems to be happening more and more over the last few years with all of the outsourcing many manufacturers are doing now to other countries..

grg_hbbs 08-25-2010 02:32 PM

I checked the coil, the part that goes to the distributor cap and its getting 12 volts cold, dont know if that helps but if i was checking the wrong thing please let me know what to check and ill do it. thanks again.

Dr. Venture 08-25-2010 02:42 PM

Was the ECM flashed? Why did you change the eCM? If your old one works plug it in and see if the car starts.

UABYJ94 08-25-2010 03:57 PM

Ok take your dist cap off and have someone turn the engine over and make sure the rotor is turning.. While the cap is off look underneath at the firing points and make sure thy aren't burnt.
Side question..has the distributer been taken out?
If the rotor button is turning then bring your engine to TDC and verify the #1 plug wire is attached to the cap in the correct location, then verify the rest of the wires are in their prospective location.
If the rotor button is not turning you could have a broken timing chain.

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