Paint Gun pressure drop

I have done a lot of auto painting before but I have never ran into this problem. While free-flowing the air pressure flows fine. But as soon as I fully depress the trigger for painting the pressure starts to fluctuate. It paints for 1-4 seconds then stops painting then starts painting again. This is consistant for paints and primers. I have even tried different paint guns which I have about 5. All I can think of is the regulator which I usually run at about 50psi and fine tune at the gun. So I brought the pressure up to 60-65psi and the problem persists. All I can think is that it HAS to be the regulator, but I run all my power tools with no problems, it doesn't seem to do that with anything else. Does anyone have any idea. I have even tried adding more reducer thinking that maybe it was the paint viscos. Anybody have any ideas? ...am I an idiot? What am I missing?:screwy:

Is this a HVLP or Suction gun
If HVLP check the regulator at the gun.
If it is a suction gun, check the vent that lets air into your paint cup as the paint is pulled out. This vent can get clogged easily.

This happens immediatly as I start painting. Paint gun is clean and clear. The vent hole was my first guess. I definatly checked that. It continues to spray steady air. I have even disassembled the gun and cleaned the entire insides. I switched guns and the other ones do the same thing. Even the touch up guns. It HAS to be the regulator. I have an old cheap primer gun and that is the only gun it doesn't seem to do anything to. I have even dilluted my paints. It still does it. I was thinking of getting a smaller pressure regulator and using it, then raising the original regulator up to about 90psi. I tried raising the pressure up to 70psi and the problem seems to have supressed. However, I can't exactly do a descent paint job at 70psi. It's about 50% overspray. I haven't pulled the regulator apart. I think I am going to try that. Maybe there is something causing this in the line. It's just such a wierd problem. Thanks again!

I run 100 psi regulated at the air compressor, to 40 psi at a regulated water separator, to 10 psi regulated at the gun.
Your suction gun may work OK because it has a lower air flow requirement.
I found that if I tried to regulate from the moisture separator, it didn't work worth a crap. By doing the middle regulator and the regulator at the gun my spray pressure became more consistend and controllable. The surge of air that you get when you first hit the trigger was eliminated.
It also helped to have the moisture separator to reduce the water sprayed out of the gun into your paint job.
Even if you replace the suspected bad requlator, I would definately add a regulator at the gun.