Topic: No spark

[Raistlinalpha]

I have a 94 yj that was operating until last night. Two nights ago I recharged a K&N filter and installed that. I also took some electrical cleaner and hosed the alternator. Climbed underneath and put an oxygen sensor in. The jeep fired up and sounded better than ever. The next night I went out to move it and it would crank but not fire. I could smell the gas and took the filter off. I spent the rest of the night searching forums...including this one.

I checked for spark and nothing at the coil. Not thinking...I instantly replaced it...nothing. Next I tested the coil plug and no juice ( I know this should have happened first). I pulled the negative cable hoping to reset the computer. No spark. I remember the same problem with my XJ an dit was the crank position sensor. I changed that out and still no spark. I read on this forum about the map sensor which surprisingly kept the vehicle from even turning over...changed that....nothing. I tried in nuetral and park....nothing..so I would assume the nuetral safety switch isn't the problem.

I am a bit of a loss here. I am new to wrenching and learning as I go. Any advice or suggestions?

[Bounty Hunter]

ASD, auto shutdown relay.

[Raistlinalpha]

Huh, thats an idea. Is there any way to know if it is bad besides replacing it and seeing if it starts then? I am impatient and the part store is closed.

[aw12345]

Jumper it across the connector with a short piece of wire

[Raistlinalpha]

It has started to rain. I will have to wait until tomorrow. I will give you an update after I have installed the new relay.

[Bounty Hunter]

Swap with another relay.  Check every fuse and mini-fuse in the PDC under the hood.

[Raistlinalpha]

  I checked every fuse and replaced the relay with a new one. Still nothing. I checked the coil plug and still nothing. I have looked over all the vacuum lines and plugs that I physically can and everything seems to be in order. I have a couple of club members who might swing by tonight. I will keep you updated.

[Jeffy]

Did you ever try to recover any Error codes from the PCM?

[aw12345]

Well here is something to consider, if the fuel pump runs and the injectors are pulsing look at the coil see if it gets power and it switches on and of on the primary terminals if it does that its time to go buy a coil. if none of that is happening start looking at the crank sensor

[Raistlinalpha]

Update... Couple jeepers came out and looked it over with me. Found a bare wire and corrected that. It was after that we tested the plug for the coil and it is now throwing 10 v. This was not happening earlier today when testing. When testing the plug from the coil, we would get two small sparks when turning the key on but nothing when cranking. Just in effort to try and cover all bases, I am going to pull the new coil off and clean the mounting bracket to make sure it is grounding correctly.

Error codes from key trick...
12. Direct battery input to PCM was disconnected within the last 50 key-on cycles.

33. One site says "An open or shorted condition detected in the A/C clutch relay circuit" 
     Another site says "Air conditioning clutch relay circuit open or shorted (may be in the wide-open-throttle cutoff circuit or normal on early 80's models if you don't have air conditioning)"

[Raistlinalpha]

Well here is something to consider, if the fuel pump runs and the injectors are pulsing look at the coil see if it gets power and it switches on and of on the primary terminals if it does that its time to go buy a coil. if none of that is happening start looking at the crank sensor

It is possible that I bought a defective coil or crank sensor but those where just replaced two days ago. Keep in mind that I am a newbie. It would seem that something is not letting the coil through the main sparks needed to kick.

[Jeffy]

Update... Couple jeepers came out and looked it over with me. Found a bare wire and corrected that. It was after that we tested the plug for the coil and it is now throwing 10 v. This was not happening earlier today when testing. When testing the plug from the coil, we would get two small sparks when turning the key on but nothing when cranking. Just in effort to try and cover all bases, I am going to pull the new coil off and clean the mounting bracket to make sure it is grounding correctly.

Error codes from key trick...
12. Direct battery input to PCM was disconnected within the last 50 key-on cycles.

33. One site says "An open or shorted condition detected in the A/C clutch relay circuit" 
     Another site says "Air conditioning clutch relay circuit open or shorted (may be in the wide-open-throttle cutoff circuit or normal on early 80's models if you don't have air conditioning)"

33 means nothing in this case.  It always comes up on 2.5L's w/o A/C.

You know if you have a friend with a similar Jeep, you can swap parts till something works.  Might be worth it to double check the coil and the CPS.

[aw12345]

Since you said you smelled fuel meaning that most likely the inje3ctors are pulsing which means there is a signal from the cps to trigger the ignition module so its time to look at the coil and related wiring you can verify the injectors pulsing by using a noid lilght in one of the inkector plugs or ysing one of the little light bulbs for the dash ilumination as a noid lightbend the little wires on the light bulb down and insert on either side of the injector connecter than crank and see if the light bulb flickers

[Raistlinalpha]

Since you said you smelled fuel meaning that most likely the inje3ctors are pulsing which means there is a signal from the cps to trigger the ignition module so its time to look at the coil and related wiring you can verify the injectors pulsing by using a noid lilght in one of the inkector plugs or ysing one of the little light bulbs for the dash ilumination as a noid lightbend the little wires on the light bulb down and insert on either side of the injector connecter than crank and see if the light bulb flickers

Handy trick, I will have to give it a try.

[Raistlinalpha]

I am unable to get under the hood until tonight to test the injectors but thinking about the problem at my desk. I have found a diagram of the distributor and they show a Sync Signal Generator/camshaft position sensor. It is located below the pulse ring in the distributor housing.

The dealer says they have it listed as a distributor pickup plate. Any thoughts on this?