> I have always wondered why a cold engine stalls. You have spark, air and
> fuel. Isn't that enough?
> Why does it have to warm up.
> I know it does, but just curious why.
There are several reasons, probably the most significant is that the fuel
doesn't mix thoroughly with the air (evaporate) and large droplets don't burn as
well. The droplets of fuel also have a tendency to settle out and puddle in the
intake manifold. There's also the problem that carburetors mix fuel & air based
on volume, while the optimum mixture is determined by relative masses. Cold air
is denser (less volume for the same mass) and so the mixture goes lean when the
carb is sucking cold air.
It's also harder to light a cold fuel/air mix, plus the coil resistance is high
and the battery voltage low, which tends to amplify any limitations of the
ignition system.
Randall
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