Volkswagen: Bus does not keep running, vacuum lines, pressure fuel

Question
I just replace the engine (long block) in my 79 bus. When I try to start, the
engine runs for 3 seconds and then dies. I sort-circuited the fuel pump and the
problem persists. I checked all vacuum lines, and cannot find a leak. All
connectors are in place. What can it be?

Answer
It sounds like you are getting fuel to the cold start valve (known as the 5th injector) but not the actual injectors.  This could explain the 3 second run time, but hard to say.  You should try pulling one of the injectors, place it in a jar, have someone crank the engine and see if it sprays fuel.  If not, the reasons could be: no fuel pressure(fuel pump), no signal (from computer), or a fuel line/injector blockage(dirt/rust).  Try it and get back with your results.