The say use the oil pressure switch so the pump shuts off when you stall, if you do use the OPS it should only be used as the source to switch a relay with the power for the pump coming from the ignition.
On mine, the supply for my pump comes off of a relay which operates when the ignition is switched on, this supply goes via a 15amp fuse and a inertia switch to the pump.
I always thought that if the pump did not run until you have sufficient oil pressure it may cause starting problems if the car had been idle especially with carburettors, but that's just my opinion
Guy SB Lowe o *arrowup*o
The ZETEC is now running here