My neighbor's motor would not crank so I removed the fuel supply module and found the high pressure pump locked up. The lift pump would spin and the float switch checked out OK as well. I recommended to my neighbor to replace both pumps, float switch and fuel pressure regulator. I installed both pumps with new seals for each and put it back on the motor. Ran it today and it runs fine up to about 4000 RPMs. Over 4000, it will cut out and when I back off throttle it catches up and will take back off again. Never shuts off or alarms alhtough it is idling a little low sometimes as low as 6500 or as high as 8000. I've checked all fuel lines, changed both fuel filters, checked the tank, tank vent and tank suction tube (does not have anti-siphon valve in tank suction tube fitting) but I installed a primer bulb at tank to provide an in line check valve to prevent gas from flowing back into tank when lift pump shuts off. I do have just under 1/4 tank, maybe 4 gallons so thinking it may be sucking air once the boat get to sloshing that gas around. Any other ideas on what's causing it to cut out at the higher RPMs?
