Ok, my friends 540 just had the lower end gone through. New crank and bearings. A Moroso high volume pump was used. Oil pressure is good when first started runs up to 60psi at speed, come off plane and at idle it drops to 0 zip nothing. What the hell is going on here? It is almost like the pump loses its prime.

Shut it off and restart and it climbs up again.

Maybe pick-up tube came off pump. Full pan, pump is below the oil line.

I am positive it is welded

What oil filter are you using ? A couple guys here have had filters fail and cause a lack of pressure in the past few months .

Not my motor but the same guy built my old motor and he used napa/wix performance filter.

Well that's a great filter . I would check to make sure , always check the stupid overlooked stuff first .

that was the first thing I told him to do...change oil and filter.

It was welded, I have seen them come off before.

Pick up is off or the pump was never tightened to the main
cap. Pull it apart before you hurt it. Cut filter open and if clean you should be ok.

Thanks for the advise, I just want to stress that this is NOT MY MOTOR once again as I have a boat for sale here in the classifieds. Jesus, no good deed goes unpunished! This motor has a sister motor in a big tub powerquest with an interweb retarded owner.

What is being suggested does not make sense, how does the pump still make pressure under high rpm when oil is low in the pan and in the upper end?