Re: electric fuel pumps

Posted by Lex On 2016/7/29 21:20:04

The "redundancy" of the electric pump is twofold. First, and most importantly, it cycles fuel through the system more quickly than with a mechanical pump to help prevent vapor lock, but this will only be effective if the system is plumbed with a return loop. Instead of any vaporized fuel or air pockets needing to be pulled through the returnless system and the carburetor by the factory mechanical pump, vaporized fuel is returned to the tank, and the carb can draw from a more solid stream of cooler fuel.

Second, it takes some work away from the mechanical pump, extending its life somewhat. Note that an electric pump can fully replace a mechanical pump, if the pressure doesn't pulse too much and the pressure regulator is set properly.

Regarding the problems while driving, vapor lock is most likely while restarting the vehicle after a heat soak. Engine and chassis heat bleeds into the lines, with no fast-moving air to cool it, and vaporizes some fuel. It is definitely possible to have this problem while driving, but I suspect a weak mechanical pump delivering substandard pressure is a more likely culprit.