Yamaha 90hp 2 Stroke Outboard Engine 2003 - No Power Underload

gary.claridge84

Recruit
Joined
Sep 30, 2012
Messages
1
I have got a Yamaha 90 hp 2 Stroke Outboard Engine 2003 model.

I have plenty of Power but when I under load it pretty much stalls.

I have checked the Fuel Pump, Carbs, Fuel Lines, Spark Plugs & Coils also checked piston pressure.

When plugged in the mufflers it's running fine but when attached to the boat I get the problems

Has anyone had this problem if so How did you resolve it.
 

Bamaman1

Lieutenant Commander
Joined
May 15, 2011
Messages
1,895
Re: Yamaha 90hp 2 Stroke Outboard Engine 2003 - No Power Underload

I don't understand how you could easily "test" the items mentioned.

When in doubt, change the plugs, fuel pump membrane, clean the carbs and fuel filter. That's a $65 investment--not including a couple hours' time.

Also make sure you're getting adequate fuel volume--checking the fuel lines, bulb and siphon in your fuel tank. You might make sure the fuel tank has adequate ventilation.

When you find the problem, it's probably very minor--as long as your engine has good compression.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Yamaha 90hp 2 Stroke Outboard Engine 2003 - No Power Underload

In 10 years have your carbs ever been removed, disassembled and cleaned?....maybe plugged carb jets...
 
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