Tom :
As I see it, true vapor lock is, as Roy described, when the fuel boils
in the line between the pump and the tank (or inside the pump), and the
pump no longer delivers liquid fuel to the carbs. Leaving you on the
side of the road, in a bad mood <g>
However, the term tends to be applied to other problems with fuel
vaporizing in the wrong place, the most common of which is the float
bowl. This is also called percolation, which strictly speaking refers
to extra fuel being carried through the jets by rising bubbles of vapor,
like a percolator coffee pot. Usually, the result is just an extremely
rich mixture and the engine will still run with lots of throttle
opening, clouds of black smoke, etc.
Since the line between the pump and the carbs is under pressure, the
boiling point is higher, and problems here are much less common. They
are also usually less severe, since the vapor just gets blown out
through the bowl vents (causing the mixture to go rich if the bowl vents
to the carb throat), and the new liquid fuel coming in will cool the hot
spot.
So, the answer to your question is yes, there are several distinct
problems, with different symptoms, that tend to be lumped together under
the term 'vapor lock'.
Randall
Tom Parker wrote:
>
> Perhaps there is more than one problem, first the pump itself (assuming
> mechanical) can cause the fuel within it to vaporise, preventing the pump from
> pumping much. Second, the carb can vaporise the fuel in the float chamber,
> causing all sorts of weirdness to the mixture.
>
> Comments?
>
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