50 hp can't get past 3000 rpms

[walter405]

My son in law has a 50 HP 2006 2 stroke which will not go past 3000 RPMs. Unable to ID problems which are reoccurring. No problems with the engine until he left it in Florida in the hot sun for several months unused. Had it serviced 2 years ago by authorized yamaha dealer. Rebuilt carbs ran fine for awhile. Then the same issue.

Everybody told him it was his carbs. so he purchased 3 new carbs and fuel pump. Issue still remains. Tried another portable fuel tank, new plugs, spark seems ok. I did compression check for him bottom 105, mid 110 and top 115. Any other idea before I he wasted his money and should have brought to a another authorized yamaha mech.

[99yam40]

stuff hiding in lines and pump will hit carbs when fired up.

Lines may be falling apart due to the fuel we have to run now a days

Cannot let fuel sit for any time and if it does you need to drain and clean the whole system

[walter405]

Thanks for the reply, he should replace all engine fuel supply lines. Any way it could be electrical in nature?

[99yam40]

He can test the CDI inputs and outputs as the service manual calls for along with the spark testing on each plug to make sure there is proper voltage if you think it is voltage problem

[walter405]

Update

After a week with the mechanic mystery solved. Shop owner son's worked on the boat for a few days without any luck. The old man decided to figure it out on his own. Plugged gas supply straight into the engine bypassing gas connecting (as he instructed his sons to do), eureka! Engine took off nearly knocked him out of the boat. Crimped gas connection, 20 buck part (FUEL PIPE JOINT COMP).