My yamaha outboard starts and runs fine at an idle but flutters past 1/4 throtle?

Question

need advise please , thanks

Answer 1

I had this same exact problem with mine. A couple of things you should check. First off clean the carb and air filter. Second off, try adding some dry gas. When the engine is reved it is asking for more fuel and the more fuel the more water. So it runs at idle because there isn't enough water to effect it. Try that. Hope that helps.

Answer 2

carbed or EFI or DFI?  

electronic ignition or points/condenser/distributor?

2 stroke or 4 stroke?

choke plates or primer/enrichener system?

what horsepower?

describe "flutter".  

does it make full RPMs or not?  

will it plane the boat (did it used to plane the boat)?

done any recent maintenance?

with the info you've provided, I can only narrow it down to three possibilities:

low compression.

inadequate spark.

fuel starvation.

compression test and spark test.  

for the spark test, use an inline tester outside the cylinder and set the gap for 1/4" if you have old-school points/condenser, or 7/16" if you have electronic ignition.

report your results.

fuel line holding pressure?

fresh fuel?

fuel tank vent open and clear?

inspect fuel tank for water and debris.

inspect fuel lines for leaks.

Answer 3

I had the problem with the fuel line that made a bend where it left the fuel hatch. Take out one of the fuel cans.

Make sure your electric choke is open. The switch under the ignition.

Answer 4

Clean your carb especially the jets, should work fine.  I make the assumption this is a small engine, like 10 hp.