I have a 1996 f150 5.0 129k on it.. oil pressure gauge is going nuts this started a week ago. The min.this stated I parked truck.. things we have done in order replaced oil sending unit.. didn't work side questions does this model have 2 oil sending units?.. than we did oil pump this did have issues along with play.. than put together problem stayed.. so we did the oil pump pick up screen.. along with new oil and a oil system cleaner. Problem stayed.. did one more cleaning and pulled the valve covers thinking it was slugg there was none but there was oil up there. When truck is running it goes nuts when it warms up. I seen something about a oil pressure valve any insight on that will help too..ty all I know I have seen this problem talked about a lot but I am running into a wall should I get a new motor

 

There's a small chance that there might be something stuck in the opening for the oil pressure sending unit. I've only seen it happen once but it caused the gauge to jump around at times. Get a barbed brass fitting that will screw in where the sending unit goes. Hook a piece of hose to it and run it to a catch bottle. Start the truck up for about 10 seconds then shut it off. Put the sending unit back in and see if it still does it.

Also, while the sending unit is out check to make sure there's nothing in the opening on it.

 

OK cool do you know if there is 2 sending units on this motor? I only found one and we replaced it

 

There should only be one unit. More than that would confuse the dash gauge.

 

Yep, only 1 oil sending unit.

 

Considering the cost of a new motor it might be worthwhile to get a real oil pressure gauge that will screw into the oil pressure sending unit hole so that (after you flush it a touch the way crownman said) you can fire it up and see what a real gauge says the pressure actually is.
Don't want to spend any more money trying to fix a problem that may not even actually exist.
The dash gauge is an electrical readout of a signal provided by an electrical sending unit. Lots of room for readout error there.
I had one once that had an intermittently plugged pickup screen (long story) but the other indicator besides the dash gauge was that when the pressure dropped, the lifters would start clacking like crazy.

 

Thanks bud I will be giving this a try. So if gauge is going crazy the engine may still make a little knock when pressure is at low?