How hard is it to fix a 1990 f150 inline 6 engine with no oil pressure?
Depends on the problem. If just a sensor. (which it usually is) Easy. $12-15 dollar part screws into engine block (usually on drivers side - or at least it is on my 1986 F-150 - 4.9L 300ci inline 6cyl) If an oil pump... then more money, time and trouble.
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