I'm glad you have good pressure.

Seems funny tho that you said you had pressure numerous times at idle...then at 4000 rpm's you got zero.

Run i till it won't run, the you know you have a problem

in spite of what some want to tell you these senders go bad all the time. I have changed out dozens over the years and all acted like yours. oil pressure will not jump around that rapidly or radically in a motor. if you are losing pressure it will go up and down but not "jump" or only work at certain rpm. the sender however will develop dead spots and as pressure changes by even a half pound could put it a dead spot. any time pressure is jumpy you should change out the sender before you worry about anything else.

I believe we said to change the sender first...numerous times. Thanks for the input tho.

theres a trick to making all these piezo type sensors for oil press and fuel pressure etc live.... assuming you don't want to run mechanical gages , you use a short piece of high pressure rubber line with the appropriate fittings to remote locate the sensor from the motor and you externally ground it. what this does is isolate it from all the vibration and heat that kills these things and gives it a nice solid reliable ground.. these consumer grade electric sensors are just scrap on their best day anyway and personally, i would never run anything other than a mech oil pess gage anyway but thats just me. on all of these applications you can just remote mount the sensors out of harms way and it will make all the dif in them living and dieing all the time...

That was my first guess also. I've replaced gages with the same part exact part number and the new gage would not act right with the old sender. New gage and sender is in order.

I like the electric gauge in the dash, but also like to mount a mechanical gauge in the engine room for double checking.

Something like this (ignore the STBD one, I dropped it and the needle was off. It was replaced shortly after the pic):

I like that idea sir.

sure. i understand completely... but you aren't standing in the engine bay when you are going 75 mph at 5300 rpm... and wouldn't it sort of be a better idea if the gages you were actually looking at and relying on to save your ass actually worked ? think about it... with this set up you are saying " gee the gages in my dash are such sht that i have to have a back up set somewhere else " huh ? that's like the guy that told me the reason he loved the MSD stuff was because it was cheap so he could carry spares and it was easy to replace every time it failed...

Here we go