2000 Yamaha F50 high rpm in idle.

Andersen222

Cadet
Joined
Jul 20, 2021
Messages
19
Hello guys.

I have a 2000 Yamaha F50 outboard.
When i start the engine cold no problems appear, i will then sail getting the engine to mid range/high rpm without issues, sailing like it should be.

But when i put it out of gear back to neutral, the rpm will slowly increase by itself.
I can then turn of the engine, and the rpm at neutral is normal again, but when i put it in gear and back to neutral, the rpm will raise again..

Any suggestions on what could be wrong?
Could it be something with the Choke Solenoid?

Picture of how my carb linkage looks like attached.
 

Attachments

  • carburetor-link-diagram-yamaha-f50-e-d-t-h-l-x-d2498da931.png
    carburetor-link-diagram-yamaha-f50-e-d-t-h-l-x-d2498da931.png
    41.2 KB · Views: 2

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
you need to inspect the linkages to see if something is sticking and not returning to the idle position.
even the linkage to the timing advance
 

Andersen222

Cadet
Joined
Jul 20, 2021
Messages
19
What pos number is the linkage for timing advance?

I’ve read on some other threads that a faulty choke solenoid could cause this issue aswell, or am i wrong?
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
I would think if it has a choke and the linkage hangs up there could be a problem.
as I said look to see if something is hanging up keeping everything from going to the idle position.
 

Andersen222

Cadet
Joined
Jul 20, 2021
Messages
19
I will have a look when it’s possible, and i will be back for further assistance if i need it 😉
 

Andersen222

Cadet
Joined
Jul 20, 2021
Messages
19
So after having a look on the linkage, it’s not hanging up. And after some search trying to find out how the fuel enrichment system works, i think it maybe could be the prime starter assy?

so as i understand the choke solenoid is only active during startup, as the starter is engaged. What the thermo switch that the solenoid is connected to is for, i dont know? Maybe you can tell?

The thermal plunger(prime starter assy) is extending over time, lowering the idle rmp until the engine is warm.

in case this prime starter is not working, i guess i could be running higher rpm in idle with the engine being warm.
Rpms will be even higher when engine is hot than when the engine is cold?
 

Andersen222

Cadet
Joined
Jul 20, 2021
Messages
19
Maybe the thermal switch which is connected to the choke solenoid, will disable the solenoid function in case the engine is already warm/hot at startup?
 
Top