I have an 01 optimax 225 w/ an 05 power head. Recently I went out and when I got up on plane it was running great. I ran about 3 miles up river and came off plane when passing a small sail boat. When I tried to get going again she would shake, shudder and then stall right away. When i would just gradually increase throttle it will run just fine up to about 220 rpm and then start stalling.
I changed the fuel filter/water separator and drained it out. Also changed the primer bulb.
Took it back out on the river and no better.
I am thinking it is the square diaphragm pump but not sure. Any help is greatly appreciated!