90hp 2 stroke , high end problems

[mlaw270]

My 7 year old 90hp 2 stroke will not kick into high speed but will idle and cruise at 5 to 10 knots without much of a problem. Just had the carbs replaced this summer because of this but the problem recurred within weeks. Seems to run ok at high speed when I put the manual choke on. My fuel is clean and new each time I use the boat. Any suggestions?

[robert graham]

The choke is attempting to overcome a lean fuel mixture caused by dirty carbs, may need cleaning, synchronizing, check fuel pump and entire fuel delivery system from tank to carbs. Are your carbs new or just cleaned/rebuilt?

[mlaw270]

The carbs are new and the problem recurred within weeks of putting them on . Ran great for the first week.

[robert graham]

Sounds like dirty carbs/jets. Have you checked/cleaned your fuel filter under cowl? Do you have a fuel/water separater? Good Luck and let us know what you find.

[99yam40]

Why did you replace the carbs instead of just cleaning them?
If they were all corroded from water sitting in them then you need to make sure the fuel tank and lines are clean.

Trash or dried up fuel from the tank, fuel lines, primer bulb, and even the fuel pump will plug up a jet very easily, but is not that hard to clear by pulling carbs and cleaning.

Best to use the 10 micron filter like was stated, but you need to clean or replace the pump and lines on motor also to make sure it does not happen again soon.

[mlaw270]

The carbs were replaced because the dealer said they were too corroded. A 10 micron filter was placed after the carbs were replaced. Is there a place where I can get the step by step instructions for removing and cleaning the carbs? I will replace the fuel pump and lines also.

[robert graham]

Buy a Yamaha Outboard Manual for motor and it explains all this. Drain each carb onto a clean white rag just to get an idea of what's in each one. Also a good idea to drain them a few times a year and before shut-down periods of several weeks or more. With your drain plugs out, pump primer bulb to "flush" float chamber with fresh fuel, then replace plugs, very easy job on the 90HP because carbs are easy to get at. Use Stabil Marine all the time. Good Luck!