Finely got a chance to do some more testing of the pump today I disconnected the weep tube for the heck of it no improvement. I installed a tee and some hose between the pump and carb with another gauge, both gauges reed the same 4.5 psi but when I clamp off the line to the carb I won't get any more than 5 psi from the pump and the gauge at the carb will drop to 0 as it should. Starting to think its the cam loab since I have two pumps with low pressure and I can't get the rated pressure out of the new one. Any thoughts?

The SBC fuel pump eccentric should have a lift of .345"-.334". This came directly from Crane tech support.

how about the metal tube going from filter to pump, have seen gunk build up in them.

many marine engine remaners regrind the cams they used for the build. You either have the fuel pump cam lobe too small or the incorrect fuel pump rod (tad too short) that is under stroking the fuel pump causing your low fuel pressure.

We see these new mechanical fuel pumps that cause too much fuel pressure from being over stroked - the fix for that is thicker gaskets and or a proper spacer to obtain the proper fuel pressure - this has been a very common problem for the last 2 years (at least 20 to 25 apps) even buying OEM Mercruiser mechanical fuel pumps.

IMO the fuel pump arm might be the problem as it is under stroking causing your low fuel pressure issue. Make sure you are using the correct mechanical fuel pump for your app also (just saying). What Sierra part # being use for your appd. I just had one that would not pump at all for a 2008 - 3.0 Mercruiser.