Bostich trim air cap 1512 over pressure and won't shut off
I read your trouble shooting page and I'm not sure I follow or my compressor isn't following the exact symptoms...
The compressor builds pressure normally right up to 150psi which is where it's supposed to shut off. Instead, the pressure relief valve (unloader?) kicks open and spews air while the compressor keeps running. If I turn the compressor off and hold the valve shut with my hand, I can shoot a few nails but of course it runs out of pressure soon enough. That makes me think the relief valve is working properly but is it likely to be the check valve or the pressure switch? (I haven't figured out where the pressure switch is yet)
I took the end off of the check valve and the spring loaded seal looks ok to me...