Thread: Engine won't run with choke flap fully closed

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With a manual choke you have to mimic the action of the thermostatic choke control as the engine warms. If you fully close the choke you will get no air through the carburetor, and yes it is normal for the engine to die - no air, no fuel, nothing to burn. An automatic choke is going to be adjusted to be cracked open about 1/8" to 3/16" when fully closed (a drill bit of that size will fit between the choke plate and the carb housing, front & back) to compensate for cold fuel & air (less atomization), plus it has a choke pulloff link that will open the choke plate at WOT - that's why you can "floor it" to clear a flooded condition with an automatic choke. As the engine warms the choke will open proportionally with temperature so that it is fully open as your water temp gauge is getting to mid-range. With a manual choke you have to find that "sweet spot" where your engine is getting just enough air to start, but not too much so that it's too lean to fire with fuel that's too cold to atomize fully. You never want to close the choke plate 100%.

Ahh, interesting, I really appreciate the thorough response. Well that's definitely a relief to hear. So there's less atomization because the gas is cooler and therefore denser?

Perhaps I should start a new thread for this, but I got a vacuum gauge to do some carb tuning and I found the intake manifold vacuum (at idle) is very low, approximately 6". And what really worries me is the lack of fluctuation upon accelerating/decelerating.

I'm thinking it's most likely a vacuum leak, however I am also considering a timing issue. I'll evaluate the situation more when I get the carb rebuilt though. Thanks again for the awesome and quick response!