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Old 11-22-2015, 07:44 PM
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No re-start after engine at operating temp

2007 JK with 104k miles starts fine when cold, runs ok but get poor mileage. Once it reaches operating temp and turn it off, it may crank with no start or fire for a sec but immediately stalls. I have to either wait 10-15 minutes or use starting fluid to fire it up. Once started again, runs ok.

Have since replaced coolant sensor and t-stat, crank position sensor, front O2 sensors, cleaned throttle body and map sensor, seafoamed, looked for vacuum or exhaust leaks and have tried the 'spray around the manifold' but no change in idle (But I do see a bit of what looks like coolant leakage). Plugs are good. Had dealer do all applicable repair bulletins, but in response to the start issue, they said since no code at the time, "bring it back when you have a CEL" (not gonna do it - done with dealer).

I get intermittent lean codes on bank 1 and 2.

Took fuse box out and tried to get to the lower board to check the fuel pump relay but could not figure out how to separate the two boards without breaking something.

Have not dropped the tank to check the pump/filter, but am hesitant to think its the filter or check valve since it starts fine when cold and runs ok. Only a hot engine issue.

Scanned today and got readings that I'm hoping someone can take a peek at to see if anything stands out - have seen many posts with similar issues, but not a clear solution. Any input appreciated!

After several minutes running at idle...
Abs tps 12.6%
Eng speed 686 rpm
Baro pres 29.5"hg
Calc load 36.9%
MAP 9.4"hg
Coolant 196F
Ign adv 3.5 deg
St ftrm1 -0.8%
St ftrm2 -1.6%
Lt ftrm1 32.8%
Lt ftrm2 32.8%
Abs load 23.9%
Rel tps 2.0%
Throt cmd 2.0%
Abs tps B 12.2%
Acc pos D 8.6%
Acc pos E 4.3%
Egr err 0.0%
Egr cmd 0.0%
Cat temp1 1121 deg F
Cat temp2 1121 deg F
Evap purge 23.5%
Fuel trim b1s1 -1.6%
Fuel trim b2s1 -1.6%
Cmd eq rat 0.999
O2S b1s2 0.820v
O2S b2s2 0.800v
O2S b1s1 0.625v
O2S b2s1 0.665v
VPWR 14.422v

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Old 12-06-2015, 08:21 PM
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More info since my post -

Had some coolant leakage at manifold gasket and thought maybe a vacuum leak due to manifold so installed new lower gasket and plenum gaskets - did valve cover gaskets, EGR gaskets and new plugs while at it since I had access to everything. All of that went fine but it did not resolve no draft when hot.

Tested fuel pressure today thinking I would see leak down on either the supply or injector side - went from 0 with kit initially connected to 35 when key on but engine not fired up to 40 when engine running. Ran until operating temp and shut off. Interestingly, hot engine caused the pressure to rise as high as 52 psi and no leak down after 10 minutes. Engine started this time after hot, pressure back to 40. Ran for 15 minutes or so, same results and it started again after sitting got about 10 minutes, although it did sputter and almost stalled once.

I understand my pressure should be at 58 +/- 2...and pump us not serviceable, has to give new module. I can do this easy, but don't want to throw $200 and a couple of hours into it on another 'shot at the problem (although still favorable to $1200 dealer outlook on pump replacement). Given today's readings it seems my pump is underperforming, but I'm not seeing why it would be causing no start when it fired at 35 psi, runs at 40 and climbs to 50 when heat soaking.

Any thoughts?

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Old 12-06-2015, 08:27 PM   #3
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When I read your first post I thought it sounded like a fuel issue. Very odd readings. I'm somewhat new to Jeeps...anyone here know where the fuel pressure is regulated?
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Old 12-06-2015, 08:48 PM
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Thank for the reply - regulator, filter, etc. are all in integrated fuel pump assembly - not serviceable separately. This has me stumped - will likely go ahead and swap out the pump next weekend anyway since I'm not getting right pressure and do get occasional lean codes, but if not fixed through that then I am at a complete loss. Would hate to ditch my Wrangler but this us too undependable for us.

I've gotten an impression through other posts outside of the forum that a hot engine can vaporize the fuel at the rail - wonder if that could cause pressure to remain in the form of vapor, maybe preventing combustion - and the vapor pressure keeping the fuel back from the rail (is this vapor lock I've read about?) - if so can this be caused by underperforming pump pressure or am I completely not looking at this correctly? Thanks
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Old 12-06-2015, 09:00 PM   #5
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Im thinking your pressure regulator is dumping fuel through the bypass return to the tank. Then you are starving for fuel?
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Old 12-07-2015, 09:00 PM
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Beyond me - given the bypass is already in the tank, you mean maybe it's just in a bit of a loop cycle vs. pumping full capacity to the rail? I'm guessing here but maybe I should check for a voltage drop before I toss a new module in. I'm definitely not an electrician but think maybe I can find a YouTube video to walk me through it. Will have to wait for the weekend and will see what I can do. Thanks for the suggestions!
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Old 12-07-2015, 09:25 PM
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I meant given that the regulator is already in the tank...
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Old 12-07-2015, 10:17 PM   #8
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I think you're looking at it correctly. Any time I had a problem with a F.I. engine not running properly; stalling, dying, stumbling, when hot, it was due to a bad/weak fuel pump not putting out the correct pressure. That's also where I would start.
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Old 02-01-2016, 04:37 PM   #9
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Resolution?

Any further information on this? I am experiencing the same on a 2008 with 68k miles.
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Old 02-05-2016, 07:38 PM
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Hi - no, I have not fixed it yet - I'm at a point where I am going to simply replace the fuel pump since my pressure never reaches spec, but won't be able to get around to it until weekend of the 19th. If that doesn't resolve it I'm done with this POS and it's going to be a trade in. Having to order the pump module - no one in Richmond has it in stock - not even dealers. Last 5 vehicles have been Jeeps (only the latest being a JK) - but wondering if it's time to move on...

BTW - I do have a workaround to get started - keep a can of starting fluid and a screwdriver, open intake tube at manifold (not at air filter) and spray into intake - then fire it up - has done the trick for me each time. Also on short trips into a store or something I take both sets of keys and just leave the damn thing running - just have to manully lock the doors since key fob won't work while running.
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Old 02-06-2016, 11:16 AM   #11
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Sorry to hear it. Ours has always started eventually. To verify, from your thread. You have not replaced the following (please correct me if I'm wrong).

Coil Pack
Plugs (you said they were fine)
Wires
Cam Position Sensor

Here is what I've done.

Had major coolant dump (had a slow leak for over a year, probably water pump) from the intake manifold gasket. Replaced Intake Manifold Gasket and Water pump under lifetime max-care warranty. I first noticed the hot-no-start condition right after the failure, but THEN my wife told me it had been giving her trouble for a while.

My first component I replaced was the Cam Position Sensor. I then immediately had one of the worst no start conditions I've had (Cranked over and over without firing a lick. Engine turning over just fine, so it's not a key or neutral switch issue). I should also note that the dealer didn't close my air-box properly, so it was pulling air around the filter at this time, and I was at the car wash after washing the jeep (engine compartment was dry).

I then replaced the Crank Position Sensor and noticed a significant improvement in drivability. Still seems to be weak on starting when hot, but it starts then stumbles instead of not firing at all.

I am replacing Coil-Pack, Plugs and Wires this weekend. I have had significant issues with coil-packs in the past (mostly ford products), and they have been sensitive to heat, so I'm thinking this might be an issue.
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Old 02-06-2016, 04:32 PM   #12
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Sorry to hear it. Ours has always started eventually. To verify, from your thread. You have not replaced the following (please correct me if I'm wrong).

Coil Pack
Plugs (you said they were fine)
Wires
Cam Position Sensor

Here is what I've done.

Had major coolant dump (had a slow leak for over a year, probably water pump) from the intake manifold gasket. Replaced Intake Manifold Gasket and Water pump under lifetime max-care warranty. I first noticed the hot-no-start condition right after the failure, but THEN my wife told me it had been giving her trouble for a while.

My first component I replaced was the Cam Position Sensor. I then immediately had one of the worst no start conditions I've had (Cranked over and over without firing a lick. Engine turning over just fine, so it's not a key or neutral switch issue). I should also note that the dealer didn't close my air-box properly, so it was pulling air around the filter at this time, and I was at the car wash after washing the jeep (engine compartment was dry).

I then replaced the Crank Position Sensor and noticed a significant improvement in drivability. Still seems to be weak on starting when hot, but it starts then stumbles instead of not firing at all.

I am replacing Coil-Pack, Plugs and Wires this weekend. I have had significant issues with coil-packs in the past (mostly ford products), and they have been sensitive to heat, so I'm thinking this might be an issue.
Getting a little out of my league with fuel pressures but I can tell you the very first thing that came to my mind was coil pack. It is a very common problem with warm no starts. When it gets too hot the voltage drops and not enough spark to turn over. It does make sense it starts with starting fluid being highly flammable.
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Old 02-06-2016, 04:56 PM   #13
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The more I read your posts I don't believe its a fuel issue. You said your fuel mileage has tanked and fuel pressure was a as low as 35psi. That should not be an issue on a hot start. It seems your getting the fuel needed. Leads me more to believe coil pack. Try to get a voltage reading from the pack on cold start and then get a reading when hot. Good luck.
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Old 02-06-2016, 10:58 PM
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I was thinking it would not be the coil pack if it's starting with fluid, but you make a reasonable point - will add the voltage test to the list since I still need to to the voltage test to the pump. Thanks for the suggestion.
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Old 02-06-2016, 11:06 PM
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Mthompson33 - I did replace the plugs when I had taken the manifold off to replace the lower gasket (I also had a leak) - since I had easier access to things while it was apart I figured why not - but the ones I took out were not really bad - replaced anyway. Not all due to the no-start, I have replaced the crank sensor, front O2 sensors, t-stat, coolant temp sensor, flushed radiator, cleaned intake manifold and throttle body, seafoamed top end, checked all wiring, vacuum test, fuel pressure test. I have taken the coil pack off and inspected but didn't think it's that - if it was failing when hot, starter fluid shouldn't make a difference and once it starts it runs fine (but nepeddler makes a point I should follow up on). Mine to will always 'eventually' start, but I tire of wating 20 minutes or so each time so take the short cut.

I do have reservations about it being the pump seems I would have other related issues and not sure why it starts fine cold - many posts say replaced and problem remains - but since it seems fuel delivery related I will do a voltage drop test (along with test coil pack) first to make sure it's getting full power, if it is, I'm replacing the pump. I get very poor gas mileage anyway, so weak fuel pump, whether due to weak power to it or obstructed flow seems plausible.
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Old 02-06-2016, 11:25 PM   #16
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Did the dealership do the Camshaft (not crank) position sensor replacement per the TSB? http://project-jk.com/images/tsb/TSB_08-023-07.pdf
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Old 02-06-2016, 11:29 PM   #17
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Also note that starter fluid doesn't rely on spark for ignition. It has a low auto-ignition temperature and will essentially do compression ignition, like a diesel engine.
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Old 02-06-2016, 11:31 PM   #18
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ignore the last statement, reading further, it looks like it would indicate spark is working if the ether works...
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Old 02-07-2016, 09:07 PM   #19
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Its not a question of any spark, its the actual intensity of the spark. A weak spark would cause poor gas mileage. Coils when failing usually fail slowly and rear their ugly head when the motor is warm.

As you stated above no cold start issues. Only issue is when warm. You stated once started warm it runs fine but poor mpg's. Poor mpg's can be explained by plenty of fuel but its not getting used efficiently. Hence its not being burned meaning weak spark.
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Old 02-07-2016, 09:18 PM   #20
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Also note that starter fluid doesn't rely on spark for ignition. It has a low auto-ignition temperature and will essentially do compression ignition, like a diesel engine.
Agreed somewhat. Starting fluid uses butane or propane. It is highly flammable. Much more than gasoline.
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Old 02-07-2016, 10:52 PM   #21
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You seem to know what you are doing, but any OBDII codes?
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Old 02-08-2016, 02:06 AM   #22
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I had a Dodge Durango that this. Turned out that a computer board had a bad solder weld that when heated up the expansion caused a short . Changed board and was fine for best 110k miles
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Old 02-08-2016, 07:12 AM   #23
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I had a Dodge Durango that this. Turned out that a computer board had a bad solder weld that when heated up the expansion caused a short . Changed board and was fine for best 110k miles
This is my thinking as well. The bad solder joint in the PCM is preventing a relay from energizing. Maybe even a bad relay in the PCM. Remove it and look at all connections for burn marks and under magnification for cracked solder joints.
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Old 02-09-2016, 11:15 PM
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Mthompson33 - re TSB I have taken it in for outstanding bulletins but will have to check this as I don't recall it. I do get the starter continuing to crank (#3), but the 2 attempts to start is more like 20 for me, and it's not just long crank time, but no result from cranking. This said, I have a symptom and since its a free fix it makes sense to try it. As in original post I get occasional lean codes, both banks - cam sensor a factor in that to your knowledge?
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Old 02-09-2016, 11:23 PM
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Nepeddler - sounds reasonable and on my list to check prior to new pump. The other thing that has steered me toward pump is the low pressure when I tested at the rail - no leak down and only around 40 when running vs spec of I think 58. Regardless, I think you make a good point.
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Old 02-09-2016, 11:27 PM
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Tweak - I get random lean fuel codes, both banks - no other codes. Comes and goes, maybe once every couple of weeks.
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Old 02-09-2016, 11:44 PM
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Ripa and Sparkie - I tried to go the relay route but ran into a problem - from what I've seen on a post of the PCM layout, it has layers of boards - the pump fuse is on the top board, but the relay is on a board under the top board. I took the whole PCM out and tried for a half hour to figure out how to separate them to get to the relay - had to put it back in or I was gonna break it. Do you know how to separate the PCM layers? Thanks in advance.
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Old 02-11-2016, 08:57 AM   #28
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Mthompson33 - re TSB I have taken it in for outstanding bulletins but will have to check this as I don't recall it. I do get the starter continuing to crank (#3), but the 2 attempts to start is more like 20 for me, and it's not just long crank time, but no result from cranking. This said, I have a symptom and since its a free fix it makes sense to try it. As in original post I get occasional lean codes, both banks - cam sensor a factor in that to your knowledge?

Not sure exactly how the the cam position sensor would drive EGT temps to indicate a lean condition...

However, I would like to report that after replacing plugs, wires, coil, cam position sens & crank position sens (at 68k miles), the drive-ability of the jeep has improved drastically. Also that after replacing the coil, a good deal of noise from under the hood just disappeared. I can still hear an exhaust leak, but the sharp tapping noise I was also experiencing is gone. This is relative to the noise after replacing plugs and wires (Coil came in a couple of days after I did the plugs and wires).

To re-cap, I changed the cam position sensor first. No noticeable improvement. Experienced a definite no-start-when-hot condition that may have been exacerbated by the intake filter box being left open by the dealership.

Then I changed the crank position sensor, with a noticeable improvement in drive-ability. (It should be noted that cam and crank sensors work together to provide the ignition system with accurate timing reference. The crank position sensor was providing an RPM Signal, but my guess is that it was glitchy and providing a poor quality signal to the TIPM. To back this up, the resistance of the Crank Position Sensor changed dramatically after tapping it against a hard surface...). started when hot, but did have a rough start that then died if I didn't pump the accelerator.

Based on the way these things operate, I would probably replace the crank and cam position sensors as a pair.

Then I changed plugs and wires. Factory Champion Platinum plugs and OmixAda wires. I honestly didn't seem to get much difference with new plugs and wires. At 68k miles, this didn't surprise me much, but the dealer made an issue that my plugs were due per maintenance schedule (8 years), so I figured if I continued to have a problem and wanted them to address it, I would have to either replace the plugs myself or pay them to do it... However, after changing the plugs and wires I was unable to recreate the rough starting when hot.

Changed Coil Pack - Drastically quieter operation of the engine.

Basic thoughts, I agree that this may be a weak-spark condition causing this, and that Mopar ignition systems are notoriously weak (going back to the 70's). When one thing goes wrong on a Mopar ignition in my experience, it's basically time to do a full system refresh...

Any other sensors I should replace based on this principle?

Another thing that popped up on my radar, but doesn't seem to be my issue... I just learned about the evaporative Canister and purge valve. I wasn't familiar with this piece of equipment, but it can cause a similar condition after filling up the tank with fuel. You might check your purge valve to make sure it hasn't failed open. Pretty easy, right next to the battery. I just pulled the fuel lines loose and tried to suck on the outlet (intake) side of the valve. no leak. Might also try pulling the line to the intake and plugging the intake, next time you have the problem before using the starter fluid.
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Old 02-11-2016, 10:07 PM
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Thanks for the info, mthompson - so you are still experiencing no start after all of those replacements? As for your question on other sensors I will say that when I cleaned my throttle body I took the map sensor out and it was near completely clogged with gunk. Used sensor cleaner and cleaned it out - after all this much quieter but no change on hot start (but at $25 I should likely have just replaced it). I'm going to spend some time this weekend testing the coil, voltage to pump, etc. and if that points me to the problem I'll start replacing things next weekend.
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Old 02-12-2016, 01:21 PM   #30
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I have not had a "no start" condition, or even a "slow start" condition since replacing the plugs & wires.

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