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Thread: Cranks but won't start

  1. #1
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    Feb 2007
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    Longmont, CO
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    Default Cranks but won't start

    Cranks but won't start
    This is on a 2006 LJ, manual.

    The jeep suddenly did not start after work.
    It will crank just fine, but will not start.
    If I spray starter fluid in the throttle body, it will run few a seconds.
    I used the Horn relay as a replacement for the fuel pump relay. Still does not start. The horn work, regardless of which relay I use.
    There are no OBDII codes. I figure is the Cam Position Sensor or Crank Position sensor were out, they would throw a code. I replaced both of them about 10000miles ago.
    Are there other Fuel Pump fuses besides just the relay in the PDC?
    How can I prove the fuel pump is shot?
    Would a dead fuel pump throw a code?
    What else could it be?






    Update: 04-JAN-2018

    It was indeed the fuel pump. When I took off the fuel line there were only a few drops of gas. Upon installation of the new pump, putting the ignition in start produced the normal pressurization sound. Engine started immediately and ran great on my morning commute.

    Here is the pump I used as a replacement.

    https://www.amazon.com/Bosch-67756-O.../dp/B000BZGCWY
    Last edited by Beowulf; 01-04-2018 at 10:53 PM.
    2006 AEV Unlimited Rubicon. Silver. 6-speed. 34x10.5R17 BFG KO2. OME ZJ/LJ. Nth TT. Alloy Shafts. 4.56 gears.

  2. #2
    Join Date
    Jun 2014
    Location
    Louisville Kentucky
    Posts
    850
    Crank sensor is always a likely culprit. Did you replace them with OEM parts or autostore parts?

    Have someone turn the key to on (not crank) while you listen back at the tank for the fuel pump to kick on for approximately 3 seconds to prime the fuel lines. Dead pump won't throw a code.

    The computer uses the crank and cam sensors in conjunction to time the injectors. Since starting fluid will get it started, it sounds like you have a fuel issue and I would start there for sure.

    Try swapping the horn with the ASD relay... ASD is the built in security function that won't allow injectors to fire if it doesn't work... This is unlikely but worth eliminating as a possibility

  3. #3
    Join Date
    Nov 2015
    Location
    York, PA
    Posts
    77
    Had the same problem with my now 20 year old TJ three separate times over the years. First two times it was the fuel pump and the most recent time a few months ago, it was the PCM.

    If it is your fuel pump, make sure you buy a Bosch. The AeroTek is junk and was my first replacement pump that only lasted 3 years before it failed and left me stranded jn the woods.

    A few months ago, a year after replacing my fuel pump and both sensors it wouldn't start. It would start with starting fluid but woyld not stay running. Ended up being the oroginal PCM finally going bad.

    I bought a remanufactured PCM with a lifetime warranty from a company in New York for $200 versus buying a new one from MOPAR for $600 that only had a one year and 12k mile warranty.

    Never had an issue with my sensors, but hoping to avoid problems down the road I did replace them at 150k with MOPAR OEM replacements a year ago after reading some other users problems with AutoZone and NAPA knockoffs that failed prematurely.

    Good Luck!

    Sent from my SAMSUNG-SM-G891A using Tapatalk

  4. #4
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    Aug 2016
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    las Vegas
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    60
    Beowulf

    Get a fuel pressure guage and see what ya got going on.

  5. #5
    Join Date
    Feb 2011
    Location
    SouthEastern Michigan
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    217
    Quote Originally Posted by BulldoginaJeepwithaColt View Post
    Had the same problem with my now 20 year old TJ three separate times over the years. First two times it was the fuel pump and the most recent time a few months ago, it was the PCM.

    If it is your fuel pump, make sure you buy a Bosch. The AeroTek is junk and was my first replacement pump that only lasted 3 years before it failed and left me stranded jn the woods.

    A few months ago, a year after replacing my fuel pump and both sensors it wouldn't start. It would start with starting fluid but woyld not stay running. Ended up being the oroginal PCM finally going bad.

    I bought a remanufactured PCM with a lifetime warranty from a company in New York for $200 versus buying a new one from MOPAR for $600 that only had a one year and 12k mile warranty.

    Never had an issue with my sensors, but hoping to avoid problems down the road I did replace them at 150k with MOPAR OEM replacements a year ago after reading some other users problems with AutoZone and NAPA knockoffs that failed prematurely.

    Good Luck!

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    Do you have a link to your PCM source, for future reference?
    JEEP The AR-15 of the automotive world

  6. #6
    Join Date
    Nov 2015
    Location
    York, PA
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    77
    Quote Originally Posted by Zeep View Post
    Do you have a link to your PCM source, for future reference?
    The company was called Flagship One Inc, out of Rockaway, NY. Just Google the company for their internet address, I ended up just calling them on the phone to place my order.

    Replacement PCM was right around $200 including priority US Mail. Took about two weeks to get receive it since they didn't have one in stock at the time.

    Most other places wanted well over $600 for a replacement. I also found another company that I could send my original to for repair, but depending upon the degree of or what all was was damaged they would NOT guarantee that they could repair it. In that event I would have had to buy another one in addition to paying for their labor and effort on the orginal. So I nixed that as an option.

    I might just buy another one to have a spare since I plan on keeping this TJ as long as I can.

    Sent from my SAMSUNG-SM-G891A using Tapatalk

  7. #7
    Join Date
    Feb 2011
    Location
    SouthEastern Michigan
    Posts
    217
    Just had a quick look, $640 for a '05!
    JEEP The AR-15 of the automotive world

  8. #8
    Join Date
    Feb 2007
    Location
    Longmont, CO
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    I'm really hoping it is not the PCM. I have the tank down now. Sadly, no one in town has a new pump. I ordered up the Bosch unit. I'll have it in on Wednesday. Once in, I will report back.
    2006 AEV Unlimited Rubicon. Silver. 6-speed. 34x10.5R17 BFG KO2. OME ZJ/LJ. Nth TT. Alloy Shafts. 4.56 gears.

  9. #9
    Join Date
    Jun 2014
    Location
    Louisville Kentucky
    Posts
    850
    Quote Originally Posted by Beowulf View Post
    I'm really hoping it is not the PCM. I have the tank down now. Sadly, no one in town has a new pump. I ordered up the Bosch unit. I'll have it in on Wednesday. Once in, I will report back.
    Did you listen for it to make noise when you turned the key? You can also do a "spot check" of the fuel rail... Prime the system by turning the key and not starting it, and then use a rag to push in on the Schrader valve and see if gaS "shoots" out.

    Doesn't mean it has the correct fuel pressure. But if it has none then that's a problem

  10. #10
    Join Date
    Feb 2011
    Location
    Calgary, alberta
    Posts
    61
    My 05 didn’t have the schrader valve on the fuel rail.

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