I have an 89 Civic lx with the 1.5l non-Vtech engine that I recently rebuilt, new pistons and new lower end bearings, head rebuilt, now it is losing oil pressure after about 5 minutes of idling. it is a little out of time, thats a bug I havent worked out yet but it will jump to 50 psi for about 5 minutes and then start slowly falling until it reaches zero. this is the second gauge ive used. and the oil pick up tube has a new gasket on it. is it losing prime or does it need to be perfectly timed or do I just need a new oil pump?? whats up?
Dan McClain

 

Replace your oil pump. Especially if you didnt when you were rebuilding it, otherwise you will be rebuilding it again here real soon. the timing does not matter for pressure. If the crank is turning, the oil pump will create and maintain pressure. If it dont, the pump is going or gone out.