Hey all, I am new to this forum as well as the problem I am gonna try to describe. I was given a 1990 Ford Ranger 2.3 Liter with 60,000 miles on it. When the truck was brought to me the lifters were extremely loud. The owner of the truck told me it sat for a while. I decided to do a tune up to the truck (oil and filter change plugs wires, ect.....)to see if that cured the problem. No such luck. Lifter noise was still there. At this point I remover the valve cover and started the engine. There was really no oil....not like there should be....laying in the head. After starting I noticed no oil to the lifters or cam. I brought the engine RPM's up to approx. 2000 and still no oil. I should of been splattered in the face with oil at that RPM but there was no oil. I did some reading on the possibility of oil pump being clogged on these engines due to oil pan gasket material getting stuck in the pick-up screen. So I removed the oil filter and started truck momentarily to see if there is any pressure and there is. There is no noise from the bottom end bearings at all everything is happening up top. My questions are....
1. Is there a possibility that the oil pickup screen is partially blocked?
2. I am assuming there is a pressure relief on the pump......could this be the problem?
3 Does anyone have a break down of the upper oiling system of this engine so I can see the possible problem spots?

I have kinda drawn a blank here and any help would be great.