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cold start vs hot start wtf

Discussion in 'The Garage' started by bobalob, Oct 29, 2005.

  1. bobalob

    bobalob 1/2 ton status

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    So for cold starts two pumps and she will fire right up but if engine is warm, like when getting gas or running errands, I can pump as much as I want but get nothing so I have to crank it with WOT and that gives me about 50% chance of start up. Failing that it takes about 30 minutes for it to cool down enough to want to start. :mad: I have a carter afb on a 350 and am wondering if choke is supposed to close on warm start or is that just on cold? :confused: I guess I just figured when I put the clutch all the way to the floor on warm start up it would close choke. maybe I just invented that in my head :( . Obviously I am a noob so any thoughts, advice , or trouble shooting would be great. :bow:
     
  2. 1977k5

    1977k5 3/4 ton status Vendor

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    Pumping the gas is what sets the choke (at least on every carb I have ever dealt with). The choke should still close (activate) even when the engine is warm (if you pump the gas), then when the engine starts it will sense that the engine is warm and the choke will open. Your problem sounds like vapor lock to me. It could be a general carb problem as well (you may need to rebuild and readjust your carb). I would make sure that none of your fuel lines are running close to any heat source, and consider switching to an electric fuel pump (you can get one from any auto parts store for ~$30-40).
     
  3. 3 on the tree

    3 on the tree 1/2 ton status

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    Choke SHOULD be open on hot start. I have had quite a few Carter carbs on different vehicles. Hot start all you should have to do is hit the key, no pumping the gas pedal. On a couple of them that were not right, I had to just crack the gas pedal and crank it to start.
     
  4. bobalob

    bobalob 1/2 ton status

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    what exzactly is vapor lock?
     
  5. beater_k20

    beater_k20 Banned

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    the WOT makes me think that its too rich, and flooding itself. how old is the carb? when was the last time it was rebuilt?
    that is how to start a flooded engine. stop pumping it so many times, and i bet you dont have the problem anymore. is this your first carbed vehicle? my '77 is dead stock. pump it twice after its been sitting for a week or two, and once its warm, just hit the key.
     
  6. bobalob

    bobalob 1/2 ton status

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    when I dont pump it or give it WOT the starter just grinds away until batt gives out :dunno:
     
  7. 1977k5

    1977k5 3/4 ton status Vendor

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    Vapor lock is when the fuel in your fuel lines boils (becomes vapor). Your pump can only pump fluid, so no fuel gets moved through the lines and your engine doesn't get any fuel. You may want to check out your cap and rotor, spark plugs and wires. They can cause hard starts as well (and they are easy to check).
     
  8. diesel4me

    diesel4me 1 ton status Premium Member

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    do ya??

    If its an older AFB,it might have passages casted into the base for exhaust gasses to pre heat the carb's base(old Buick and Caddy carbs had it set up that way--not sure what yours might be like,the later aftermarket AFB's just had a smooth flat base-)..those older style ones needed a stainless steel "shim" gasket sandwiched between 2 paper gaskets to seal it properly to the manifold..I recall those carbs having hot re-start problems,and poor idle, if that shim gasket was left off..

    Some carbs need a thick base "insulator" gasket to help keep heat from boiling the gas after shutting it off after driving awhile..if you have an aluminum adaptor or spacer,they act as an insulator,so ignore this if you do..

    If you used an adaptor to put the AFB on a Q-jet stock manifold,be sure its installed with the right side facing the intake (that matches the Q-jet base)--I see lots of them installed upside down,or with the wrong gaskets-and sometimes the resulting vacuum leak wont show up until the motor heats up,affecting starting and idle..

    It could just be your choke is closing too soon after a warm shut down--or the carb is leaking gas into the intake and flooding it while it sits..time to do some detective work...try wiring the choke open,and see if it still does it.. :doah: :crazy:
     
  9. jhellwig

    jhellwig 1/2 ton status

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    I have the same problem with a brand new edelbrock preformer. It wasn't as extream though. I belieave I have the problem narrowed down to the carb getting to hot and boiling the fuel out of it.
     
  10. 88trailblazer

    88trailblazer 1/2 ton status

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    When its warm and not starting, manually pull on the trottle bracket and look in the carb to see if gas is actually making it in. That should tell you if its vapor lock. I just got my 78 started yesterday. I kept on screwing with the carb which didn't help. Finally, I did a full ignition tuneup (wires, cap, rotor, module, coil) which solved the problem. Unfortunatly, I fried the starter from cranking it so many times and now i have to try and re-adjust the carb back to the original settings
     
  11. bobalob

    bobalob 1/2 ton status

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    i did pull throttle manually and it squirts just fine, so no vapor lock. leaning towards flooding now.
     

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