[Vwdiesel] Oil Pressure

[Libbybapa at wmconnect.com]

I have an '84 vanagon that is converted to an I4 2.0L gas motor using diesel 
vanagon parts.  I bought it already converted (if I had done the conversion it 
would be diesel).  I park it in my driveway in the same spot.  I have a 
mechanical oil pressure gauge that reads pressure from the head.  When I start it 
up after it has been sitting overnight, sometimes it has oil pressure 
immediately, sometimes it is many seconds (and lifter noise) before there is pressure.  
Sometimes it will tick away at idle reading 0 seemingly indefinitely until I 
raise the idle to 1000 rpm.  Then oil pressure is almost immediate.  Is the 
relief valve the only possible culprit?  I vaguely recall someone talking about 
oil passageway check valves in the crank?  Could that be the issue?
Andrew