what would cause this? when i turn the key on..pump primes and shuts off as it is suppose to..I have a gauge hooked to the rail and she holds a steady 43 psi...crank the engine and pump starts running again..turn key off or stop cranking and pump continues to run for about 30 seconds before shutting off..what gives? oh and car is an 85 iroc..305 auto...

 

My first guess is that the auxiliary oil pressure switch is holding closed until the oil pressure bleeds off. That does seem like a long time, since my '86 only does that for about five seconds after shutdown. Either the oil pressure switch is sluggish, you have very high oil pressure and low flow, or the port which feeds the switch may be filled with sludge.