I changed the oil pump in my 96 jeep grand cherokee, and now it's not reading any pressure on the dash gauge.
The oil filter is filling up with oil as soon as I crank the engine, so I figure it's pumping oil. Any Idea what might cause this?
I dont have a mechanical gauge so I cant test pressure at the sending unit....

 

It turns out that the cheap paper gasket that came with the pump failed and pushed out. There was a small gap between the motor and the pump. This was enough to keep any pressure from building up, even though oil was making it to the filter.
I got a better gasket, and the oil pressure is great now.
Hope this helps someone!