Primer Very Weak

I have a primer that seems very weak.  I put in new o'rings from Vernon and that part seems to be okay.  The problem is that when pushing the primer in, it does not seem to develop any pressure.  When I bench test it with avgas, it will pump okay with both ends open but the slightest bit of back pressure on the output port causes the fuel to pump back out the input port.  When installed in the airplane it does not feel right, it feels like there is nothing there.  Other aircraft I have flown (cessnas) have had a definite pressure I could feel when pushing in the primer.  This pump supplies fuel to 2 orifices in the forward 2 cylinders of the engine so there will be some pressure needed to inject the fuel.
In the picture, the top blue AN fitting is at the output port.  It is not a plain fitting. It has a check valve inside, even though from the outside it appears to be a simple fitting.  The bottom blue AN fitting is the input port and this fitting does not have a check valve.
The spring-loaded center pin on the pump shaft only seats when the primer is in the closed position and this seems to be okay.
My question is, does anyone have experience with this primer or know where I could get support for it?

Thanks!

John Earl
1946 415-C
C85-12F
N99891