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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4716
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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2001 Yamaha 50 hp 2 stroke outboard. When throttle is advanced

Customer Question

2001 Yamaha 50 hp 2 stroke outboard.
When throttle is advanced and forward gear engaged, engine initially stalls or threatens to stall. If you keep trying to get it to take the throttle, it eventually takes off and runs gangbusters at high speed.

What's going on?

JB Lanexa, VA
Submitted: 6 years ago.
Category: Boat
Expert:  Jeff G. replied 6 years ago.
I will be happy to assist you. If you have a question or need clarification please post back at any time.
Easiest thing to try is to richen the idle mixture slightly. The mixture screw is on the top starboard side of each carb. Turn the screw out 1/8 turn (CCW). Try this setting and see if it takes the fuel better. Do this a couple times and see if the take off improves.
If it doesn't then the carbs may need to come apart again and new kits installed, you may still have some trash or gum in the idle/midrange circuit.
Post back with questions.
Customer: replied 6 years ago.
Thanks for your answer, but my son found a small leak in the fuel delivery hose on the top carb.
He is replacingall of the fuel lines. If that doesn't do the trick, we will try enriching the mixture as you suggested.
Expert:  Jeff G. replied 6 years ago.
Keep in mind the engine is using the fuel in the float bowls. While a leaking hose can cause problems, and is a hazard, you will probably find a carb problem. Usually a small leak won't cause the problems you are having. But lets hope luck is with you and that is all you find wrong.

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