Re: 75 hp Yamaha boat motor
All we know is that you have a 75 HP Yamaha. Model year and S/N might be helpful? Regular gas is what the engine requires so it would not cause fouling of the plugs. Injectors don't generally cause an overly rich condition but rather a lean condition so that too is an unlikely cause. A bad pressure regulator on an EFI engine can cause a very rich condition but at this point we have no idea exactly which engine you have.
