I have a 95 F-350 I have no oil pressure at idle acording to the factory gauge. I soon as I touch the gas it come up where it has been any ideas. I am also fighting a problem of running rough and smoking. I hope the 2 are conected.
It all started begining of June smoking and running ruff. Couldn't find the problem so after a few day of working on it decided to just drive it and see what happens. IT cleared up after about 10 miles. Ran great for about 50 miles. Then it came back. Never cleared up. It died and I had to change the IPR to get it to fire back up. It will run now just the gauge is barried in the corner at idle, but as soon as u touch the gas it jumps up. I have the oil cooler off it now to look at the check valve. I don't know anything about it. It has a carbon fibr looking piece on the bottom towards the oil filter, but on the side towards the block it has a piece that is pressed in with a spring behind it. Should it have some kind of plunger too? I was told something in there can go bad. Guys sorry so long, But I want my truck to run again. Oh yeah it has 90,000 on it.

 

The factory gauge is fake: under 7psi the needle goes to the far left, over 7psi the needle stays in the middle.The fiber disk in the oil cooler is to dump oil pressure if it gets to high. I've only heard that if the disk falls out of place you would have low oil psi (i think).

 

Did you try a new LP sending unit ,,,If the truck will run ,,you will have oil pressure

If the by pass valves on the cooler are still capped there should not be an issue there...

 

Put a manual gauge on it. The stocker just won't give you a clear story especially if its not working correctly.