73 Z28 Hard to Start.

Discussion in 'Troubleshooting & Diagnosis' started by JRowe, Dec 26, 2019.

  1. JRowe

    JRowe Veteran Member

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    I actually have an 80 z28 with a holley and it's hard to start too. My cars sit and work for about 6 months none stop. I used to see fuel come out when I had pumped the throttle but now I dont. So it sounds like I need to pump diaphragm. Thanks, I can google hot to do that. Thanks.
     
  2. berg2695

    berg2695 Veteran Member

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    Maybe the fuel in the tank is too old and sour and hard to light.
     
    Last edited: Dec 26, 2019
  3. ronzz572

    ronzz572 Veteran Member Lifetime Gold Member

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    The needle valve could be stuck closed if it sat for a long time. Ethanol fuels will turn into a sticky gummy substance in the carb and gum it up. If you get fuel at the carb fuel line and it still won't start. That probably the problem. What I recently did on a similar situation was poor some fresh gas into the carb vent stack and let it sit for about a hour or so. About a shot glass full or 2. It worked for me. After the car ran for a while it will flush out the gummy residue. Then put some fuel stabilizer in it and run it some more before you let it sit again. I use only racing gas in my hi performance engines my 70 L78 and Z28. Never had any problems. Todays Ethanol fuels are crap for our old muscle cars.
     
  4. JRowe

    JRowe Veteran Member

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    I checked the fuel pump and it seems to work good. So I guess it's the carb...the quadrajet. I can rebuild a holley but the quads seem harder.
     
  5. Gary S

    Gary S Administrator Lifetime Gold Member

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    I'm still not sure you have a problem. Try driving it every day and see if the hard start goes away. With a carb and today's fuel, it evaporates out quite fast when not used. Then, cranking the engine to get the fuel back to the carb is normal. If it starts right up when used regularly, you don't have a problem at all.
     
  6. Vettenick

    Vettenick Vettenick

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    If you look down the carb's primary and move the throttle (with the engine off), you should see fuel coming out of the nozzles. If not, it's probably the accel pump cup in the carb. If that's the case, even when you do get it started, you should get some kind of hesitation when under acceleration, especially when cold.
     
  7. grzewnicki

    grzewnicki Veteran Member Lifetime Gold Member

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    My car has sat for weeks here in Florida and I've never had any problems starting it, I really don't think fuel is evaporating that quickly.
     
  8. Gary S

    Gary S Administrator Lifetime Gold Member

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    Replace all rubber hoses between the fuel pump and the tank. Even the smallest crack in a hose will allow it to draw in air so the fuel runs freely back to the tank. The hose can leak air, but never leak fuel because when it is running, there is vacuum in the line preventing gas leaks. When shut off, air draws in easier than fuel leaks out so you still don't have a fuel leak.
     
  9. JRowe

    JRowe Veteran Member

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    Thanks fellows for the suggestions. When I get back home I will them out.
     
  10. JRowe

    JRowe Veteran Member

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    I have replaced all the lines etc. Got a new rebuilt quadrajet from O'Reillys and it worked for awhile. I have a semi clear fuel filter and I see gas so the guess isn't leaking back out. I just have to pour some fuel in the carb and it starts and stays running and I can drive it around and it seems fine. Next morning it wont start again with out pouring more gas down it. Someone side to check the needle valve? How do I do that?
     

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