scott7689

So Im having issues with my MJ. Ive got an 88 Mj shortbed 4wd with the inline 6 and a 5 speed. I came out of work tuesday morning, got in the truck, and it wouldnt crank. I had it do it one time before and i hit it with a little starting fluid and it fired right up and hasnt given any trouble since. Until last saturday. I took about a 15 minute drive moving some furniture and when i was backing in it started to bog like it had a miss. I cut the truck off for a few minutes and when i started it back it was fine. Then it did the no starting thing tuesday morning. I have changed the distributor cap, rotor button, ignitor coil, plugs and wires, and crank position sensor. I have pulled the wire off the distributor from the coil and im not getting spark there. so my problem is before then. Im just stumped on what direction to take next.

Lowrange2

No spark to the distributor? Have you tried the coil?

They're cheap.

scott7689

yep ive already swapped the coil out. still got nothing. can you straight wire the coil on these like an old chevy?

Lowrange2

I don't see why you would. Have you tried pulling a plug out, putting the plug back in the plug wire, ground it and look at the spark?

Nothing?

scott7689

Yeah i went a step further and pulled the coil wire from the distributor and checked it for spark and im getting nothing. so i took the coil from my xj which cranked it right before i removed the coil so i know it was good and put it on the mj but still got nothing. Then i changed the crank position sensor being next in line for it getting spark and ive still got nothing.

Lowrange2

What year is the truck?

scott7689

Its an 88 model shortbed 4wd 4.0l with a 5 speed.

Lowrange2

What color is it?

Lowrange2

Kidding...

I'm not sure what to tell you without being there.

Start with the basics...

I'd start tracing wires. Verify that you actually still have power to the coil.

scott7689

lol well its red at the moment with a little weathered patina across the roof and hood. haha just trying to knock all that out in one post

scott7689

yeah my test light and I have gotten real close over the last few days. I seem to have power where i should. Just no spark. The CPS i took off the truck looks almost brand new. Im dreading that im just chasing an electrical demon. A friend of mine mentioned possibly running an old one wire chevy coil on it. possible?

DieselDaze

I had that exact truck !!!! well exact only different

best truck I ever had, period... btw, there was an article in a magazine in 1988 where they took the 2wd model added a turbo charger and raced it against a stock vet... the comanche won all 3 times they ran it....

onto your problem, the only advice I could give you is make sure you're not overlooking the coil grounding, wires and overall in general... maybe even use the coil wire off the xj as well..

i had built a top end on a chevy once, after assembling the motor I couldn't get it to start, I was completely frustrated and baffled.. one day I went out there fresh and realized that one of the small wires from the coil was disconnected... simple fix that had me stunned..... fired right up....

clean all connections with electric cleaner..

scott7689

ive been all through the wiring. It just happened suddenly and i am so baffled it is ridiculous. Got me stressed out cause the truck needs to be ready for redneck resort this weekend. im just stumped on where to go next

a737mech

have you tried ignition relay or fuses thats always the best starting point.

scott7689

ive played with all the relays and checked all the fuses. all seem to be in good working order. Can you straight wire the coil. where the red wire is running into the positive terminal on the coil...just tap into that and straight to the battery?