See full version: Adjusting idle on EFI 4 stroke
Idle speed is controlled by the ECM and the Idle Air Control valve. The plate in the throttle body should be fully closed at idle. Just check to make sure it is. If it shows any signs of being slightly open, then check your throttle cable adjustment. If it is fully closed and you're still idling high, suspect the IAC is not functioning properly. Pull it out and check that too. here
BTW, there is no idle adjusting screws on EFIs. Idle mixture and idle speed are controlled solely by the ECM. more
[links]
Main jet is located in the bottom of the carb bowl, usually buried behind the carb bowl drain screw.
It's really nothing you did per se. but if you had an error code pop up while posting, a quick freeze up during posting and/or kept clicking on Post Reply trying to get it to post then that could be the reason you and many others may see multiple posts or topics even hours later. It has more to do with forum issues since doing forum software changes that's taking longer than preferred to repair.
Better think again.
The "main jet" you are describing is not the main jet at all. You are describing the fuel inlet needle and seat.
It is merely a valve that allows fuel into the bowl as it is consumed by the engine.
If you or anyone runs across multiple posts inside a topic like this, please feel free to click on the Flag post icon to let someone know to come in and delete them, it would be appreciated. Thank you. more
You need to trash that Clymer or Seloc manual and get an original OMC factory manual for your motor.
[links]
Our certified mobile mechanics can come to you now. more
Faulty Idle Air Control Valve (ICV): Some cars are equipped with an idle air control valve to maintain idle speed. This part can malfunction due to excessive carbon buildup in the intake manifold.
Faulty Fuse: In the majority of vehicles, engine idle speed is controlled via an idle control valve (ICV). A faulty or blown fuse in other electronically controlled systems can cause the Idle Air Control (IAC) motor to malfunction, leading to a higher than normal engine idle speed. [links]
Fair, upfront & transparent pricing for all services more
If disconnected I don't see it damaging the ECU but then your motor may not idle correctly (if at all). The ECU will sense the IAC valve is disconnected and may not allow the motor to run at higher RPM. more
Perhaps the valve has become stuck. Have you tried cleaning it to see if the situation improves?
The IAC valve upon becoming defective has been known to damage an ECU. [links]
Best situation would be for a mechanic to connect the motor to a laptop computer running Yamaha software in which case the IAC valve can be told to open or close. If it is told what to do but doesn't want to do it then either time for a cleaning or a replacement valve. more