either your oil pump screen is clogged or you need a new pump
The oil pressure is dropping at this time. A clogged oil filter, clogged oil pump screen or failing oil pump can be the cause.
The oil could be dirty or the filter could be clogged. The oil pump screen could be clogged or the pump could be going bad.
Weak oil pump? Clogged oil screen?
Check the oil pressure sending unit first. The oil filter could be bad or clogged. The oil pump filter screen might be clogged, or the fuel pump could be bad.
get a new engine
Shaft from distributor could be stripped or the screen on oil pump my be clogged but most likely its the shaft coming from pump to the distributor is stripped or broke
fuel filter clogged fuel pump weak fuel line clogged
Incorrect filter, defective filter, weak oil pump, clogged oil pump strainer, clogged oil galleys, worn engine bearings, defective oil pressure gage, or defective oil pressure sending unit.
Several causes (list is not all inclusive); Clogged oil channels due to sludge or oil additive buildup, broken oil pump, low oil level.
If you have oil pressure it is working.
The 1998 F150 could have low oil pressure due to a stopped up filter, clogged screen, or bad oil pump. The pump and screen are inside of the oil pan.