Originally Posted by Fordguy545
Ummm, I think I was having this problem at the track yesterday also, and I have the electric pump near the tank(prostar500) to the regulator mounted off the carb studs. Could it be not running enough pressure into the carb?? The cheap mechanical gauge says 3psi but the electric autometer says 6 3/4psi. I have been having this problem for quite some time, and havent been able to figure out why it does it, until somebody asked if it was vaporlock yesterday :shock:
Unless the mechanical pump is failing to a point where the engine vacume is pulling the fuel faster than the pump can supply it, its not vapor lock.
Could simply be lack of delivery. (ie not enough pump) and the engine is going lean.
Vapor lock, is a function of diaphram (mechanical) pumps sucking the fuel from a fuel tank, if the fuel is too warm, from either atmospheric temps, or close proximity to a heat source (brakes or exhaust) when the pump tries to "suck" the fuel forward, instead of flowing as a liquid it flashes to vapors, and of course we cant/don't want to meter vapor gas, the carbs need liquid flow. So long as you continue to attempt to "suck" the gas forward, it continues to flash to vapor.
Thats why rear mounted electric pumps were implimented, to prevent vaporlock problems. AS you apply pressure from the source, fuel is compressed versus sucked, and is unlikly (wont) flash to vapor in the fuel line.