Re: Vapor lock poll

Posted by Owen_Dyneto On 2011/3/13 14:11:44

JW, sure - putting the fuel under pressure raises its boiling point and hence makes it more resistant to vaporizing. Everything else being equal (like ambient heat, proximity to hot surfaces, etc.) the least likely place to have vapor lock is in the line between the fuel pump and carb as it is under modest pressure (3-5 psi) much of the time. Most likely is the fuel line from the tank which is under suction as its boiling point will be slightly depressed. The fuel in the carb is under atmostpheric pressure if the percolator valve or vent is functional so it would be a candidate before the fuel line from the pump to the carb, again everything else being equal (which would be really uncommon). Knowing just where the vapor lock occurs would be fundamental to solving the problem. If the carburetor, a stuck (closed) heat riser valve would be a likely culprit.