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since 'vapor lock' seems to affect many of you on hot days, it is
important to understand what it is. gasoline has a fuel vapor pressure,
and when it is heated above a certain temp in relation to the pressure
it will vaporize. some cars with weak fuel pump pressure will actually
stop running while traveling. now the problem is that most mechanical
fuel pumps run very low pressure AND the fuel line is poorly situated in
a hot engine compartment. when you shut down the engine, the engine heat
heats the fuel line and vaporizes the fuel. when you restart the fuel
vapor flows to the carb slowly through the float valve, but any new fuel
introduced to the fuel line just vaporizes so you are in a 'loop'. there
are several good ways to reduce/eliminate this problem. one is to raise
the fuel pressure by taking the pump apart and using a stronger spring
to push the diaphragm. another is to put a metered return line to the
tank so that the circulating fuel cools the line. still another is to
cover the lines with insulation or route them where there will be less
heat. ( you certainly don't want them running over the exhaust for
instance.) also be sure your engine is not running any hotter than it
need be.
tom
This archive was generated by hypermail 2b29 : Mon Feb 21 2000 - 18:15:14 PST