2001 Mercury 200 XL stalls on WOT

Please someone help me. I have a 2001 Mercury 200HP 2 stroke that runs perfect at idle and low RPMs. Soon as I get over 3200 RPM the boat stalls out. I have to pump the primer ball and than she runs fine at idle but will not go at a high RPM under low. The water separater is almost empty until I pump the primer ball. I have changed the fuel pump, all the lines and the water separater and housing. still the same thing!! I am thinking of changing the enrichment value as someone said that could be the cause, I was under the impression that was only for the choke and starting. Any advise would be a HUGE help......

It's Not the enrichment valve.

Your mechanical pump is bad/installed wrong or you have an leak letting air in.

Thank you. I will double check all the lines and the pump. Hopefully its something I missed Thanks

Test run with a small portable fuel tank and a good hose.