hard start and dies after quick revs

Discussion in 'Troubleshooting & Diagnosis' started by 7.62fmj, Sep 30, 2017.

  1. 7.62fmj

    7.62fmj Member

    55
    0
    May 16, 2017
    Jacksonville, Fl
    Hopefully someone can help me out with this.

    Motor is a 307 bored and stroked to 333. Prior owner had it built and swapped in in 2009. It has a Holley 650 4bbl. I am unsure whether the carb was new or rebuilt at this time.

    If the car sits longer than over night it takes several 5 second cranks to start. I do two pumps then turn the key to start it up. It fires up strong then stumbles and dies. Once it's running it runs good and starts easily so I'm thinking maybe the choke is the problem.

    The other problem I'm experiencing is that cold or hot the engine will die after a quick stab of the throttle. It happens most often when parking or in a k turn like when I'm in drive, go into reverse, and then back into drive. If I accelerate in reverse then stop and go into drive it will die suddenly after I let off the gas before I can shift into drive (no stuttering or choking out that I can tell). I feel like this could also be a choke issue, but I am not sure; I'm still pretty new to this.

    Trans is a T350 if that makes any difference.
     
  2. 7.62fmj

    7.62fmj Member

    55
    0
    May 16, 2017
    Jacksonville, Fl
    A little further detail, when the car dies on startup the rpm slowly drops as it sputters out. There also doesn't go into a fast idle at all, starts up to 600rpm and settles at 500
     
  3. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    8,813
    133
    Nov 4, 2004
    Ringgold, GA
    Definitely sounds like a carb problem. Holley has some pretty good tips online. Click on link below and go to "Carburetor Tuning and Adjustments", click on the "see more" button and you should find some relevant info for your issue. https://www.holley.com/support/carburetor/
     
  4. Rdobbs1977

    Rdobbs1977 Veteran Member

    263
    8
    Dec 1, 2014
    TN
    I agree with CorkyE. Will ask just to get out of way--you've not adjusted timing lately have you? Also, have you thought about putting a vacuum gauge on there to see what your vacuum is and what the needle is doing?
     
    Cardinal likes this.
  5. 80sz

    80sz Veteran Member

    2,155
    144
    Feb 2, 2014
    Buffalo,n.y.
    Check to see if choke is closed on a cold start. Pump pedal then check removing air cleaner. Verify it has 12volts also.
     
  6. 7.62fmj

    7.62fmj Member

    55
    0
    May 16, 2017
    Jacksonville, Fl
    Good info on the Holley page; having the videos helps. Will check the choke, but the issues after reaching operating temp make me think it's either not that or there are multiple things that need adjustment/fixing. Unfortunately I'll be out of state this weekend.
     
  7. 7.62fmj

    7.62fmj Member

    55
    0
    May 16, 2017
    Jacksonville, Fl
    No timing adjustments lately. The vac gauge is on my to buy list.
     
  8. Camaro75LT

    Camaro75LT Masshole Staff Member Lifetime Gold Member

    6,539
    55
    May 17, 2001
    Boston-ish
    Are you able to verify fuel pressure? If you were losing pressure or sucking air into the line, you might experience these same issues.
     
  9. 7.62fmj

    7.62fmj Member

    55
    0
    May 16, 2017
    Jacksonville, Fl
    Had some time before work today, got the choke adjusted and she fires up beautifully. When I pulled the air filter off the choke was wide open. No longer dies after a blip of the throttle. But the fast idle is only 700. Is this ok?
     
  10. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

    1,185
    41
    Oct 2, 2013
    Milford,CT
    Most fast idles run around 1600. Sure it's on the fast idle cam?
     

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