Your regulator may need adjusting.  I purchased a new regulator.  Worked
fine but was just on the low end of the green arc on the suction gauge.  So.
I removed the safety wire and turned the regulator adjusting screw ( cannot
remember which direction) started up the engine and found the setting to be
approximately in the middle of the green arch at runup speeds.  Task
completed.  Safty wired the regulator and buttoned up the operation.  If
memory serves me correct, I think I turned the screw about two turns.

Identifying leaks are your first task. adjustment is the second.  I am under
the impression that pumps either work or they fail. Any one else have
experience on slow failures?

Bob Smiley
N94RJ.