will not restart immediatly after shut down

[The_Big_Hose]

i just swaped a grand national motor into a regal body the car starts and runs fine but when i shut it off and try the restart the engine it cranks and almost starts after letting the car sit key off for a few minutes it starts no problem a few people told me it might be the oil pressure switch any help or ideas will be greatly appreciated

 

[Turbo1dr]

Test the fuel pressure on it and see what that does first.