I have an '82 Westy, formerly diesel, converted to gasoline with a Rabbit engine.

Occasionally, when I turn the key to start, it does not turn over.  When I turn it to the "ON" position, I hear an electric motor run for several seconds, and then stop (the fuel pump?).  When I continue to turn it to the start position, on these occasions, nothing further happens.  If I then repeatedly turn the key off and back to start, usually still nothing happens.  If I then hold the key in the start position for an extended time without movement, say for 3-5 seconds, othen suddenly the engine will turn over and start.  This seems to happen more often when the engine is cold than hot.

So far I have always managed to get it to start as described.  For a couple of months it has done this maybe once every couple of weeks, but I fear the problem is getting worse as it happened four times in the last two days.

Is this an ignition switch problem?  Some solenoid?

Any help would be appreciated before it gets any worse and disables me.  
Thank you,
Paul Chubbuck