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Thread: 1996 Chevy C1500 silverado 5.7l vortec engine 2wd CRANK NO START ISSUE.

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  1. #1
    Carb and Points!
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    1996 Chevy C1500 silverado 5.7l vortec engine 2wd CRANK NO START ISSUE.

    Hello,
    As the title says I have a crank no start issue on my truck. Brief history, engine is a new gm factory 5.7l engine installed a year ago but has not been ran much untill last few months. Alot of new components on this engine all stock. New distributor, plugs, wires ,sensors, cats, and AC delco mpfi injectors. Truck was running fine good fuel trims. No codes, started up 1 morning and it fired right up and I had walked back inside for a few minutes and when I cam out it had quit running. Tried to restart and would not fire, good crank though, I have confirmed Good spark, good fuel pressure 61psi, new Delphi fuel pump, holds at 55psi for good 10 minutes. I have determined that the issue is most likely a flooded engine, oil smells like gas and the level is more then it should be. Cylinder wash. I pulled off peluim to confirm no.leaks and inspected each injector for open condition and if they were functioning as they should everything seems to be as it should be. My question is this what should my next step be, to determine the problem that caused the flood issue in the first place.I will drain and refill oil this weekend and install new plugs and hopefully get it running and post some live data as well as compression readings and fuel pressure readings.

  2. #2
    Super Moderator dave w's Avatar
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    The injectors are triggered on by the computer sending a ground pulse to the injectors. The injectors are wired with constant 12 volts when the ignition switch is in the On or Start position.

    I curious about the injector drivers in the computer? A Noid light test would be helpful information, but connecting a Noid light to the Vortec injector pod requires some out of the box thinking and creative wiring.

    dave w

  3. #3
    Fuel Injected!
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    Possible leaky poppet valve on the spider.
    6395, BHDF, 7.4 BBC lightly modded now 6395 BMHM back to BHDF

  4. #4
    Carb and Points!
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    Quote Originally Posted by myburb View Post
    Possible leaky poppet valve on the spider.
    This truck has the upgraded MPFI spider injector assy installed. No poppets. I visually inspected each injector as I was having a helper crank engine over. Also performed a leak down test. System held a steady 55 psi for over 10 minutes.

  5. #5
    Fuel Injected!
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    Is it throwing any codes? I'd check sensors that can contribute to a rich condition. Frigid coolant temp sensor, high volts on throttle position sensor, high map, etc.

  6. #6
    Carb and Points!
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    No codes. Thanks I will check all the sensors. I back off the truck let my mind and frustration clear a bit overnight. I believe that I am most likely responsible for the flooded engine issue, what with the constant cranking and starting attempts. 1 of the first things I did after a quick check as to spark and fuel status was to change the fuel pump. I also went ahead and change the coil. I just really didn't think of the engine getting flooded or it even being an issue. But it is definitely flooded so I will get that cleared out and see what we have after that. Thanks for your help, I will update asap. Got to prepare for hurricane Dorian today.

  7. #7
    Carb and Points!
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    Quote Originally Posted by dave w View Post
    The injectors are triggered on by the computer sending a ground pulse to the injectors. The injectors are wired with constant 12 volts when the ignition switch is in the On or Start position.

    I curious about the injector drivers in the computer? A Noid light test would be helpful information, but connecting a Noid light to the Vortec injector pod requires some out of the box thinking and creative wiring.

    dave w
    Yes I am aware of that I did check the plug for the injectors assy with a test light. I do have 12v and I was getting a pulse from the other side for each injector. I have never used a noid light but I know they can be a valuable dignostic tool. (Should get a set.). I am curious if I am having a issue with the ECM . It the EGR and MAF sensors are all original or at least I have not replaced them. The ECM pretty sure its original. Truck was a 1 owner and has 320000 miles on it. Engine and tranny about 200 I would have to check my notes. Same on MPFI by the way. Thanks

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