Long engine crank before firing - Jeep Commander Forums: Jeep Commander Forum
Problems / Dealer Service Having a problem with your vehicle? Were you treated fairly or poorly at a dealer? Warranty issues? Let us know.

 
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post #1 of 5 (permalink) Old 01-02-2013, 06:46 PM Thread Starter
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Long engine crank before firing

Looking for some help!

After searching thru the threads for months, I have not been able to find any threads about a problem I'm having with my 06 3.7L (QT1).

When starting, the engine cranks and cranks (between 7 to 10 seconds) before it fires. Long enough that anytime anybody is around or in the car with me, they always point it out. It has been doing this for over 4 years now and about 80k. While it was under warranty (about 31k) I took it to the dealer and they were not able to find a problem.

Despite the long crank time, it has never failed to start, and when it runs, it runs fine.

Also it only has this long crank time when I haven't driven it for over 4 hours or so. The engine will fire much more quickly when it have been driven recently. That's why the dealer cannot ever find a problem. (Leads me to believe that possibly the fuel pump loses its prime over time and the engine needs to crank longer for the fuel pump to re-prime and send the fuel, but that is an uneducated guess only!)

A couple things to note:
-current mileage is 110,000
-on the original battery (not sure if an aging battery could contribute to this)
-PCM and ESM replaced recently (original units failed)
-I'm religious to all maintenance intervals

Any help would be very much appreciated! I'm clueless and cannot seem to find answers elsewhere
Thanks!
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post #2 of 5 (permalink) Old 01-03-2013, 09:20 PM
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Is there any difference when you Prime it before starting the vehicle. You should be able to put the key in, go to Run and sit there for about 4 seconds and here the pump prime. Once it shuts off or the dash light shuts off, crank it and see how long it takes. That should let you know if its a priming issue.
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post #3 of 5 (permalink) Old 01-04-2013, 12:20 PM
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Great advise hemi! I usually do this before turning it over anyways, just habits.


2006 3.7l Silver black and crome Sport W QT1
K&N cai. Aridium 1X plugs. 1.5" Spider Trax...
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post #4 of 5 (permalink) Old 01-04-2013, 02:34 PM
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I mean thats what comes to mind, with mine, i can hear the wine when it primes.. after that i would take it to get a battery test done on it, there free at any autoparts store. that rules out the battery.. but so long as it is spinning up it should be fine... Thx rhob btw. Also since it takes a while for the issue to re-ocure i would rent or borrow a fuel pressure guage to watch what the lines doing when its primed.
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post #5 of 5 (permalink) Old 01-13-2013, 08:18 PM Thread Starter
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So letting the fuel pump prime does seem to help. Maybe cuts down on those rough starts half of the time, and I can definitely hear the pump prime.

I took it down to AutoZone and they checked the battery, everything checked out fine with it.

Hooking up a fuel pressure gauge is a great thought, that's next on my list. Since priming the pump does seem to help, but not completely, leads me to believe it is a fuel pressure issue.....but I guess in the end since it has been doing this for so long without any noticeable consequences, if I can't figure it out I won't lose too much sleep over it.
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