Ford Repair: oil psi, psi gage, oil pickup

Question
hello ken
           i have a 1992 ford expoler i can see that the oil psi gage will run nomle for day or two then it will say low oil psi for a day or more/it will move form low to to med way from time to time can you tell me why it is doing this  

Answer
CRAIG

the oil pump may be going bad.the oil pickup screen may also be plugged.i would also check the oil pressure unit,its located by the oil filter.i would replace this first.changing the oil pump or cleaning the pickup screen is a big job.the oil pump is about 20 bucks but you have to take off the intake manifold,to get the oil pan off.the reason for this you have to lift the engine up.there is alot more to this job,i just gave you a over view.hope this helps.

ken