Intermittent crank no start - '13 5.0

Discussion in '2011+ Mustang GT 5.0L Tech' started by Gabe, Jul 30, 2017.

  1. Gabe

    Gabe Whippled Coyote

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    My car started doing a crank-no-start recently, did it twice so far, once after it sat for about 2 hours as I was in for a Dr appointment 2 days ago (Friday afternoon), and again yesterday afternoon after it sat for about 1 hour.
    The first time it cranked long, no start, I tried it about 3-4 times, I paused a few seconds in-between as my wife and I looked at each other wondering if we were gonna need a tow, then tried it one more time and it started.
    Yesterday it was cranking and almost catching, but still not actually starting.
    Again, 3-4 tries, a pause, then last try it started rough but it started and stayed running.
    Once it starts, it runs great.
    Makes me think "crank position sensor".

    Car has a KB bap, and the first time it happened I was showing 38 miles to empty, so I chalked it up to maybe being low on gas and the BAP somehow caused it, but the second time it happened the tank was full, and I don't over-fill, ever.

    No codes stored, and can't blame it on the latest tune revision since it went in yesterday morning.
    Thinking it's a part starting to fail, I've heard the CPS on the 4.6 3V is known to fail, am wondering if anybody on here has any thoughts on this issue.

    Thanks in advance.
     
  2. travelers

    travelers Senior Member

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    If you have or have access to a fuel pressure cage I would check the fuel pressure. I believe it should be 65psi. If you have that with the key on and cranking then it's some where else.
    This is just a starting point to eliminate the fuel system..

    I just saw a post on another site that he had the same problem as you when he would turn the key and release it before the car started. So he found that if he held the key in the start position the car would start.
     
    Last edited: Jul 30, 2017
  3. 5lho

    5lho forum member

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    The starter is semi-computer controlled on these cars. If you crank the motor and the comp detects a no start, it can continue to turn the starter until the motor catches, even if you release the key. I've had this on both my Coyotes. i get it on the 14 now that I run E85 and have cold plugs in there.

    I've also had the system just get confused, throw a big slug of fuel in there and the motor bangs around for a sec, clearing it out. This used to happen occasionally to the 12 when I started and stopped the engine before a full warmup-drive cycle was completed.

    So, there may be nothing wrong at all, is what I'm saying.
     
  4. travelers

    travelers Senior Member

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    Now that I think of it mine did it once.
     
  5. Gabe

    Gabe Whippled Coyote

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    Haven't had a chance to test anything on it.
    Partially afraid I'll mess something up and the emissions readiness will get all screwed up, haha.
    Going for a sticker in the morning, once I get home I'll see if I can do the fuel psi test

    I did end up ordering a crank position sensor since it was only $18 shipped off eBay.
     
  6. Sky Render

    Sky Render Stig's Retarded Cousin S197 Team Member

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    Gabe, what fuel rails do you have? Can you easily hook up a cheap fuel pressure gauge?
     
  7. Gabe

    Gabe Whippled Coyote

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    Stock rails. Not sure.
     
  8. Boaisy

    Boaisy Dark Knight

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    My car had done it once, but after a couple tanks of gas, it went away. Especially the rough start part. Was probably around 30k-50k on the odo. I chalked it up to being bad gas.
     
  9. Gabe

    Gabe Whippled Coyote

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    Well, just did it again, and I noticed that as I was turning the key to the ON position I wasn't hearing the fuel pump kick on.
    So I grabbed my laptop and using the FORScan software I checked for codes and found DTC P025A - Fuel Pump Module control circuit/open

    Then it started raining and since I was outside I just grabbed the laptop and went back in the house.

    Guess I gotta check for some loose wiring.

    I recently moved some wires around back there, at the BAP and fuel pump module, so maybe I knocked something slightly loose.
     
  10. Gabe

    Gabe Whippled Coyote

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    Well, the only questionable wiring issue I found was this connector going to the ground wire which goes into the factory wiring.

    [​IMG]


    With everything connected and the car running, I could wiggle the wires and the relay and a buzzing sound would show up from the area.
    Since everything's so close together it was impossible to figure out if it was the relay or the BAP that was buzzing.
    I cut that connector off, crimped on a new connector and re-assembled, car started right up.
    I tried wiggling the wires and relay again, I think I briefly heard some buzzing again, but can't get the car NOT to start right now, so we'll see.
     
  11. Sky Render

    Sky Render Stig's Retarded Cousin S197 Team Member

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    Did you use a butt crimp connector?
     
  12. Gabe

    Gabe Whippled Coyote

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    Yes. The original connector was installed by whoever I bought the wiring or the BAP from.
     
  13. travelers

    travelers Senior Member

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    Is that gray connector a home wiring connector?
     
  14. Gabe

    Gabe Whippled Coyote

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    Lol, yeah, I capped off an unused wire. The BAP is wired to run all the time, I think that wire would've been used for the Hobbs switch.
     
  15. Sky Render

    Sky Render Stig's Retarded Cousin S197 Team Member

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    Most don't realize this, but a butt connector actually requires FOUR total crimps. You need to crimp the actual wires in the center and crimp over the insulation at the ends. The second set of crimps prevents stresses on the connection.

    I can take a picture if my description sucked.
     
  16. Gabe

    Gabe Whippled Coyote

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    I'll take a look, sure!
     
  17. Sky Render

    Sky Render Stig's Retarded Cousin S197 Team Member

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    OK, you see how there are 4 crimps? The middle two crimp the bare copper conductors and the metal part of the connector to create electrical continuity. The outer 2 are on the edges of the connector where there is no metal. Those plastic edges are crimped onto the insulated part of the wire. Those outer crimps prevents any strain forces from reaching the actual connection.

    You should then wrap this connection in heat shrink or at least electrical tape.

    Yes, I just ran down to the garage and made this just for this post.
     

    Attached Files:

  18. redfirepearlgt

    redfirepearlgt forum member

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    Poor ground would cause the problem. Not hearing that familiar FP prime sound at key on would def be a tell tail. When you get past your SMOG or E-check or whatever it is, you may wish to verify voltage @ Connector C4033 pin 1 violet /gren stripe on the FPDM module int he trunk with key on. This will verify wiring to the module and teh fuel pump control relay. You may also monitor the PWM voltage driving the pump (until prime is satisfied thus stopping the pump from running) and see if the voltage is there AND the pump in fact primes every time.

    And don't forget the fuel filter which is easily overlooked. I doubt its a crank trigger. I would expect you would have gotten a DTC/CEL for that.
     
  19. Gabe

    Gabe Whippled Coyote

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    Awesome, thanks guys!


    .
     
  20. travelers

    travelers Senior Member

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    I prefer the heat shrink connectors. They don't come apart.