I have a new remanufactured amc 360 long block. When i installed it i put on a new timing cover, new pump gears, new pump gear cover, and a new pickup tube in the pan. When i first fired it up it had great oil pressure, would jump up to about 50-60 psi cold. Then when warm it would go back around 20-25ish. Maybe a little lower sometimes but well within the acceptable range. The jeep sat for a while and i took it out yesterday right before i was going riding just to test things out. When i started it up it jumped to 25psi..stayed there the entire time i was riding even when it got warm. I go out this morning fire it up and get nothing registering on the gauge. Maybe just barely above what it is when you turn the key on. Its not a sender problem, i have an electric and a mechanical gauge. Any ideas?