Oil pressure drops

[c1500deathtrap]

Is this a motor rebuild? I would drop the pan to verify the oil pickup is properly installed and the right pickup for the pan.Either that or run a borescope through the dipstick hole.

 

[Schurkey]

1. The oil pressure sending unit on my '88 is known for short service life--it's cheap junk that fails often. I don't know if your truck uses the same crappy sending unit. (BWD S4320, NAPA 6729, Auto Zone PS150)

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2. Pressure going to zero on acceleration, then coming back to "normal" pressure , and the problem goes away after topping-off the oil sounds a lot like the screened pickup tube fell off the oil pump. As said, poke a bore scope into the pan via the drain plug.