LJ cranks but won’t start - JeepForum.com
 
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post #1 of 3 Old 09-26-2021, 12:17 AM Thread Starter
DuckRyan
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2009 JK Wrangler 
 
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LJ cranks but won’t start

I’ve been chasing a few issues and along the way of “solving them”, the has Jeep decided it no longer wants to start.

2006 Jeep Wrangler Unlimited 4.0L Automatic
This is not a daily driver, it gets driven around town, to the beach, and trail on weekends.
Currently no codes as the battery was disconnected for an extended period. Previous codes were P0455, P0456, P0440, & P0344.

Here is the initial issue that I was chasing…
It began with occasional sputtering upon acceleration and occasional reving on its own at idle/stop. I replaced the throttle position sensor and cleaned the throttle body. All seemed fine for a month or two until the issue reoccurred, this time at higher speeds. At around 50mph it occasionally sputters and and won’t allow me to go any faster. I would then pull off the road, shut the Jeep off for 10 seconds, then continue along with now issue until until the next time I drove it.

Last weekend the Jeep didn’t start because my fridge killed the battery. I jumped the battery and immediately it sounded weak. It sounded as if it was surging in and out. I noticed the AC was on so I shut it off, this caused it to sound a lot better. I vowed to simply not use the AC for a while since the top will remain off for forever.
In hopes of tackling both issues I replaced the following parts: purge valve canister, upstream O2 sensor (2), added half a can of sea foam to the fuel, spark plugs (Autolite double platinum gap .4), oil, and battery terminals.

This likely doesn’t matter but I figured I’d give as much detail and insight as possible. During the spark plug installation I found oil and gunk on one of the plugs due to a valve cover leak that I have been meaning to fix. I put it all together but one of the coil boots was not seated by mistake. The Jeep started right up but I heard and saw one of the plugs sparking and immediately shut it off. I seated the coil boot properly and it fired right up and sounded great. I took it for a 5 min test drive and it ran perfectly fine.

It sat for about 4 days. I tried starting the Jeep and it cranked but did not start. It would crank and crank as long as I was turning the ignition, Once I would let go of the ignition it would die. I was even able to hit the accelerator and the engine would rev.

Today I replaced the crankshaft and camshaft position sensor but the did not solve my issue(s).

Any insight would greatly be appreciated! PLZ HELP

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post #2 of 3 Old 09-26-2021, 02:58 AM
jtec
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jeep is STOCK - no tuners, programmers, modification to powertrain?
Do you have a scanner - can yu see live data.
What codes are you seeing now? Post All.

With a test light - when you crank engine are the injectors pulsing?
What is fuel pressure PSI?

Jeep does NOT call for double platinum, use solid core KISS.
What brand o2 sensor did you us - yes it matters.

Try this - as someone cranks engine to start spry some carb cleaner or starting* fluid into TB - did engine try to start 'fire' on the spray? That will check fuel supply.


Keep all old parts - o2, CKP, CMP etc.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 3 Old 09-26-2021, 08:22 PM Thread Starter
DuckRyan
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2009 JK Wrangler 
 
Join Date: Feb 2014
Location: Corona
Posts: 43
Quote:
Originally Posted by jtec View Post
jeep is STOCK - no tuners, programmers, modification to powertrain?
Do you have a scanner - can yu see live data.
What codes are you seeing now? Post All.

With a test light - when you crank engine are the injectors pulsing?
What is fuel pressure PSI?

Jeep does call for double platinum, use solid core KISS.
What brand o2 sensor did you us - yes it matters.

Try this - as someone cranks engine to start spry some carb cleaner or starting* fluid into TB - did engine try to start 'fire' on the spray? That will check fuel supply.


Keep all old parts - o2, CKP, CMP etc.
Thanks for the reply. The Jeep is stock when it comes to those parts. I don’t have a scanner for live data but using the three key turn method, no codes appear.

NTK O2 sensor

I sprayed started fluid in the throttle body, that didn’t change anything. I didn’t have any one around to spray and start simultaneously. I also replaced the fuel pump relay but the didn’t solve it either. Ended up putting the old one back in. I will rent a fuel pressure gauge to test further.

I still have the “old” CKP and CMP sensor but I threw away the old O2 sensor.
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