97 TJ won't start after sitting 18 days

[ChiefQM]

2.5L. It ran fine before I left on vacation. Upon return, engine cranks but won't catch. We have had monsoon rains and 100 % humidity, so I inspected inside of cap and rotor, no problem. Got variances on the coil so replaced it, still no spark. I sprayed ether into the intake and it didn't fire, so I'm reasonably certain it is a spark problem. I pulled and re-seated the relays and inspected the big fuses. I checked tight clean connections on TPS, CPS and MAP sensor. There is no Check Engine lit, either. What next? It's not the crank position sensor, which was a crowd favorite in other forums. Changed it out and it still won't start... Help me, Mr. Wizard!!

 

[redneck]

did you try the speed sensor in the distributor. That makes jeep don't start it happen to mine jeep before.

 

[ChiefQM]

Redneck, that wasn't it either. Pretty soon every sensor on the Jeep will be replaced. Methinks it's down to the computer. Anybody with suggestions feel free to chime in...

 

[Jester32]

I would lean toward crank sensor problem with no spark. Check the wiring. To it mice love to make a nest right around there as do other rodents. As it's right on top of the bell housing.

 

[Jester32]

If all else fails have a dealer try to re flash PCM it would be cheaper than a PCM itself. But they are pretty bullet proof unless it was boosted wrong. I would replace any sensors unless proven bad. You can test any sensor out there with a doom.

 

[ChiefQM]

Jester, I have replaced the crank position sensor, and the wiring is intact. I had already replaced the coil before that, and the cam position sensor in the distributor this morning. I have reset the computer again and still nada. I get no check engine light, and I have tried to see if there are any codes stored, nothing flashes. What else is there besides replacing the computer? What does reflashing do? I really hesitate to have it towed in if it's something I can do.

 

[Jester32]

The dealer will hook up a drb 3 scanner. That's the Chrysler scanner and you can read all the sensors as your cranking. You can also use a lab scope to see if all your sensors are giving a reading. The drb can flash the proper program back into memory. I work for Chrysler in Canada and do lots of that. You have to watch the live data and see that everything is reading right. The drb also has the ability to perform no start diagnostics. Make sure you have good power to the coil as well check with dvom. I don't like seeing people replace stuff that's not broken. Hard on the pocket book.

 

[carnuck]

Check the ASD relay. It will shutdown the fuel pump if bad.

 

[ChiefQM]

The dealer will hook up a drb 3 scanner. That's the Chrysler scanner and you can read all the sensors as your cranking. You can also use a lab scope to see if all your sensors are giving a reading. The drb can flash the proper program back into memory. I work for Chrysler in Canada and do lots of that. You have to watch the live data and see that everything is reading right. The drb also has the ability to perform no start diagnostics. Make sure you have good power to the coil as well check with dvom. I don't like seeing people replace stuff that's not broken. Hard on the pocket book.

Thanks, Jester, the Jeep is in the shop now. With 104K miles on the clock, I didn't feel too uncomfortable replacing the three things I did replace, as they would have quit on me sooner or later. Just disappointed that none of them solved the problem.

 

[Jester32]

Anytime. Let me know how it turns out

 

[ChiefQM]

It was indeed the computer.

 

[Jester32]

Were they able to save it or did you have to replace it