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Hey gang,

First post here but It's a doozy so here I go...

We have a 2004 Jeep Wrangler X that's been in the family since new. It's at about 85k miles and has been daily driven for the last few years but recently switched things up and it's parked more frequently but I digress...

Short Version:

-Cranks but doesn't fire. Not even a hiccup
-Starting fluid has no effect
-Spark plugs were toast. Replaced with new ones. No effect.
-Swapped camshaft position sensor and crankshaft position sensor with no effect.
-Can hear the fuel pump prime


Long version:

We went to start it and it cranks but never starts. Cranking sounds normal to me and has the usual thumpity sounds of compression so I'm assuming it's something small. Here are my troubleshooting steps.

1) removed the airbox piping and shot some starting fluid directly into the throttle body. Had no effect. Just cranks and cranks with no start.
2) Removed the coil pack and pulled the spark plugs. They were VERY worn down. Look to be the original copper plugs from 2004. Yikes. I stuck them into the coil pack and cranked the engine and they still spark! However I only tested the front 2-3 spark plugs. I replaced the spark plugs with new Bosch double platinum plugs. Reassembled everything and no different. Still no start.
3) Removed and replaced the crankshaft position sensor thinking that maybe the spark is poorly timed. Had no effect so I returned it back to the original.
4) Removed and replaced the camshaft position sensor. Also verified it's actually spinning. Had no effect so I returned it back to the original.


This is where I'm stumped. It certainly seems like one of my tests has been a false positive. If I have spark but no fuel, then why wouldn't my starting fluid make it start? Makes me think it's spark related but I visually saw sparks from at least the front 2 plugs. Might go and get a new coil pack and swap it to see if that fixes the problem.

Any thoughts or assistance would be appreciated. This is a nice, garage kept Jeep so luckily everything is pretty easy and clean.
 

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If have spark and won’t even cough with starter fluid could be timing chain jumped a few teeth

Check compression

Test spark like this

Would also check rail pressure and verify injector pulses with noid lights

Parts darts is never a good idea


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My guess is old gas. I do winters in FL, and summers in Mich, and have stuff both places. Gas just doesn't last like it used to even with Staybil.

My Harley last year wouldn't start, it had good spark, but even spraying in starting fluid it wouldn't fire at all. Same with lawn mowers etc here. But, these things have carbs, and its usually the needle valve the float operates. Clean the valve and jets, and all is well.

A few weeks ago I tried to start my Yamaha generator, it started, but surged. An internet search suggested it ended being the main jet, which has a bunch of tiny holes in it, its common for it to plug with old gas. I cleaned it, blew it out, and with fresh gas, it purrs like a kitten. Just did a chain saw today.

I am trying to run things dry after the season, but some things don't get done. With mowers, weed whackers, blowers, etc etc, its a pain.
 
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