I refer to it has the "need a new engine light".
My oil pressure switch in the KE70 comes on at 5 psi,
You may have something stuck in the relief valve of the pump holding it open, as it is unfiltered oil maybe some bearing material or dirt?
I modified my oil pump, was a bit of stuffing about, but I put in the gears from a 18R motor and run a spacer the same as those in 2TG/18RG oil pumps to make the body longer, gave me 3mm wider gears and a sh#t load more oil volume.
I have a brand new still in the Toyota box #k oil pump, was going to use it in the upright motor. PM me If you need