Ok, got my headlights working from a previous post, was a corroded wire in the bulkhead connection, now my issue.....Let me start with the back story.
My 94' dakota 3.9L had sat for about 6mo, one day i took it to town and lost oil pressure, (gauge and light). After i got it home and the engine had cooled down, I started it back up, thinking maybe it was just the sending unit, i had oil pressure, after about 10 minutes, it would drop down to zero again. After talking to a friend of mine, he said a durango he had did the same thing and it ended up being the oil pump. (As the oil heated up, gunk from the oil pan clogged the pickup screen. So i decided to change the oil pump, not a big deal, except its a 4x4 and i had to do this by myself. I got the pump changed, I put a melling HV pump in it, cleaned the oil pan, it had a lot of gunk in it. I had also ran Marvel Mystery oil, and engine flush through it both in seperate oil changes to help clean the engine, before i changed the pump. After the new pump, i started had good pressure, everything seemed fine. I let it run this morning for about 35-40 minutes, while i was tinkering outside, went to turn it off and the guage read zero, and the light was on, i do not know for how long, but the engine was still running smooth, and not lifter noise, or knocking or anything, if i give it gas, the pressure jumps back up.I read another post with almost the same problem, but not quite like mine. Any other ideas before i put a new sending unit in it? When i changed my pump i looked at the crank and the rods, and from what i could see and feel everything was ok, there was no metal in the pan that i noticed. Thanks for reading...

 

The oil pressure sensing units are notorious for being bad even new out the box. It probably is bad and replacing it is the best option. The only other thing you can do is get a mechanical gauge and check to see what the pressure reading is at those times the light should come on.

 

I had a 99 Ram that did the same thing with the 5.2. Bought it with 160k miles and it did the same thing prettymuch from the get go, but like you say no lifter noise. Ended up putting 2 oil pumps in it sending units, everything. One day before work on a -40 degree farenheight day I started my pickup to let it warm up, went in took a shower and got ready, came out and it was knockin away, got in, no oil pressure, but never heard it knock. I was angry, said the heck with it and went to work, usually turning the pickup off and on the guage would go back up, well it didn't. So off to work I went knocking away. 6 miles down the road it locked up (yes, stupid out of anger). Brought home dropped oil pan put another new pump and new mains in and its still going to this day I sold it to my mom, 260k miles and counting, and it did the losing oil pressure thing on and off until about 240k and has since started normally holding oil pressure. So my advise to you would be not to worry to much about it if it's NOT making noise or knocking. Never did get to the bottom of why, maybe guage faulty, but replaced a few sensors and 3 oil pumps, very strange....

 

Ok, finally got around to changing the oil sending unit, and everything seems to be back in working order, after i installed and tried to start it up the engine seemed to stumble on itself and ran kind rough, and my tach was way out of wack, but after a few minutes and a couple of restarts everything fell back in to place. Thanks all for your comments and advice.