2003 90HP Saltwater Merc

[DonnieG]

Motor starts OK and idles fine but when you put the throttle down it goes for about 1000 yards and the motor either quits or acts like it 's running on 1 cylinder, changed plugs and there does not seem to be a fuel problem as the plugs are wet? No very familiar with boat motors but it seemed like an electrical issue??

 

[guyjg]

Is it carbed or fuel injected? Will it keep running if you squeeze the ball pump in the fuel hose? Is this a four clinder 2+2 engine...it runs on the top two cylinders up to 1800 RPM and then the bottom two cylinders kick into action. Changed fuel filters lately? Check the fuel tank vent line for blockage. If it's carbed then the fuel pump diaphragm may be failing...you will have to take it apart to see. Try running the engine w/an auxilliary fuel tank to rule out the onboard tank.

 

[silvereagle]

Is it carbed or fuel injected? Will it keep running if you squeeze the ball pump in the fuel hose? Is this a four clinder 2+2 engine...it runs on the top two cylinders up to 1800 RPM and then the bottom two cylinders kick into action. Changed fuel filters lately? Check the fuel tank vent line for blockage. If it's carbed then the fuel pump diaphragm may be failing...you will have to take it apart to see. Try running the engine w/an auxilliary fuel tank to rule out the onboard tank.

I too has a similar issue,mine was the check valves/diaphram.