90hp Mercury cuts off at high rmp

[ranselbon]

I have a 1989 Mercury 90 hp outboard with oil injection that's cutting off at high rpm. It starts and runs great up to 1500 rpm or so, accelerates up to 3500 rpm (where i usually run it at plane) great also, but after 1 to 3 minutes it cuts off completely. After cutting off, the engine starts back fine and runs fine until planing out again. The problem started about half an hour after i put it back in the water after having some work done on the lower unit (was not used in maybe 2 months). Any advice would be greatly appreciated!

 

[guyjg]

Fuel supply to the carbs may not be sufficient due to a failing fuel pump diaphragm. The only way to be 100% sure the diaphragm is failing is to take it apart...might as well rebuild it then. You can try another fuel tank first.

 

[ranselbon]

Thank you for the quick reply! I'll check into the fuel pump and let you know how it goes.