1992 no oil pressure

I rebuilt the top end (heads rebuilt) on the 3800 motor non supercharged (180,000 miles), installed new timing gears and chain all new timing sensors and magnet (main purpose for tear down). new plunger and spring (made sure they were the exact ones in it), new oil sending sensor, new balancer. Didn't touch the pistons, they look good as does the cylinder walls (Cleaned real good). Took the plenum apart from the manifold, cleaned all parts inside and out, with new gaskets. Also the crank parts are new because when I started the first time after rebuild the motor ceased (sleaves overlapped) up on me (was told the system needed oil pressurisation on startup), and had no oil pressure. This time I have pressurised the oil system and still no oil pressure. What is the deal? I dont want to ruin it again. I bought a mechanical oil pressure gauge and installed it where the sending unit goes thinking I might have an electric gauge problem, still no oil pressure. Help!!!!!!!!!!! Please!!!!!!!!!! The repair book says on start up to take the plugs out and the ECM fuse out crank the engine untill pressure builds, nothing! Is this the right procedure? out of frustration I put the plugs back in and the ECM fuse back in, it started right up but no pressure, only let run for 5 seconds for fear of ruining the motor again NO OIL PRESSURE.

Why didn't you change the oil pump while you had it apart? They're less than $50 for your car. It's actually a kit to repair it.

Guess I left that out in my thread, a new oil pump kit was installed as well.

did you pack the oil pump housing with Vaseline or grease to prime it? you need to pack it with grease or other semi-solid lubricant to prime it or you won't get any oil pressure.

The housing was packed full of petroleum jelly as my repair manual stated. Today I took the oil filter housing off and checked the plunger and spring the plunger did not want to come out. Finallay got it out blew out the ports real good with compressed air. Put the plunger back in and it seemed to slide in and out no problem (I think it was stuck with the petrolem jelly by vacuum)Then put all back together reprimed the engine with compressed oil still no pressure? Something tells me there is a problem with the oil pump gears. Isnt there only one way to put those gears on? Any suggestions?

I would just like to let you know about my experience with no oil pressure in a 3.1 that I overhauled. When I first started the engine the oil light would stay on and after speeding up the engine it would flicker and then go out. At idle it would come back on. I put a gauge on the engine at the oil sending unit and the oil pressure was fine. I think there was air between the oil pump and the sending unit and it was giving a faulty reading. After I replaced the sending unit it was fine. Another thing I did on this same engine is when I put the timing chain on I used the wrong mark for a timing mark and The engine would lock up. Thank God I figured it out before I ruined the engine. Hope this helps you.

Appreciate the remarks, I haven't fixed the problem yet, it still sets in my shop, been kind of putting the thing off, real discouraged after all the work and rework, but, I appreciate your help, what about the oil pump, isn't their really only one way to put it back together, i don't know by just reading my repair manual, looks like only one way?