My understanding of vapor lock is the following:
In a fuel injected aircraft, a hot engine or nearby exhaust manifold can cause the liquid fuel being pumped through the fuel lines to vaporize, or as most people say, boil over. Thus, two things happen: one, the fuel pumps aren't designed to efficiently pump fuel vapors, and two, the pressure in the fuel lines as a result of the vapor attempting to occupy more space can cause the fuel not to flow through the injector and into the engine. Also, this can be caused by enough air being trapped in the fuel line either by improper venting or running a tank dry before switching.
One question, can vapor lock occur when an engine is running? If so, what's the appropriate procedure to take? Run the aux fuel pump? I know it can occur before start-up, and I'm assuming that it then takes quite some time to restart the engine as the vaporized fuel is forced out of the line. Please, if there's any flaws in what I'm stating, correct me! That's the entire purpose of this post, I need education when it comes to vapor lock. Thanks!
[Edited 2004-11-02 01:03:29]