Yamaha 20hp, water in one cylinder

[99yam40]

float is not closing off the needle properly if fuel is leaking out of bowl vent.

need to verify where the fuel is coming from

[luddovitch]

How do I verify that? Just by looking? All I see know is that fuel is coming out from the air intake when I try to start.

[99yam40]

take the silencer off so you can see the carb,
pump the primer bulb while looking for where fuel is leaking out of

[luddovitch]

take the silencer off so you can see the carb,
pump the primer buld while looking for where fuel is leaking out of

I have the silencer off when I see the fuel leak, and I dont think the fuel is coming when I prime, only when I try to start, but I might be wrong, gonna look more closely next time I try.

[luddovitch]

Ok, the fuel is leaking from the back of the carburetor when im on full choke and trying to start, not when I prime the bulb. Is this normal?

[TownsendsFJR1300]

The carb is ONLY getting fuel when it's running (from the fuel pump).

When the engine is off, the carb will leak down to a certain level

Sounds like the float and needle are stuck open FLOODING your engine.

I would first drain the carb in question(drain plug at the bottom of the bowl) maybe squirt some carb cleaner and tap the carb body (to try and loosen the needle). Might get lucky by squirting some carb cleaner down the carb fuel INLET nipple (and let it drain).

Close it back up and try again. The carb / needle may have varnished up with the old fuel sitting in it.

If that doesn't work, the carb needs to come off and cleaned..

[luddovitch]

The carb is ONLY getting fuel when it's running (from the fuel pump).

When the engine is off, the carb will leak down to a certain level

Sounds like the float and needle are stuck open FLOODING your engine.

I would first drain the carb in question(drain plug at the bottom of the bowl) maybe squirt some carb cleaner and tap the carb body (to try and loosen the needle). Might get lucky by squirting some carb cleaner down the carb fuel INLET nipple (and let it drain).

Close it back up and try again. The carb / needle may have varnished up with the old fuel sitting in it.

If that doesn't work, the carb needs to come off and cleaned..

Thanks for the answer

I have cleaned the carb in ultrasonic so I dont think its dirty but I guess I can take it apart and have a look at it.

When the engine is running it runs really good and have a good idle. It's only really hard to start when cold and sometimes after letting it sit for some minutes after it has been running. And the fuel leak when trying to start on full choke and some throttle, no leak without choke.

[TownsendsFJR1300]

Quote:

It's only really hard to start when cold and sometimes after letting it sit for some minutes after it has been running. And the fuel leak when trying to start on full choke and some throttle, no leak without choke.

Issues starting dead cold, is very likely linked to your choke system.

http://www.yamaha-motor.eu/uk/servic...-uk/index.aspx

From what I can find, (think I have the correct engine) Under the ELECTRIC PARTS 2, (part #15) is the choke solenoid which SHOULD pull the butterfly closed. (Under the INTAKE section, you have one carb with a single choke butterfly. That, of course, should be closing when starting cold.)

Can you confirm if the choke butterfly is working (closing) when activated (or not)


Re:" no leak without choke". I have no idea, doesn't make sense to me...

I'd address the choke /cold start (or lack of) as that sounds like a definite issue, then tackle the leak (if it continues)..



.

[luddovitch]

Quote:

It's only really hard to start when cold and sometimes after letting it sit for some minutes after it has been running. And the fuel leak when trying to start on full choke and some throttle, no leak without choke.

Issues starting dead cold, is very likely linked to your choke system.

Yamaha Online Parts Catalogue - Yamaha Motor UK

From what I can find, (think I have the correct engine) Under the ELECTRIC PARTS 2, (part #15) is the choke solenoid which SHOULD pull the butterfly closed. (Under the INTAKE section, you have one carb with a single choke butterfly. That, of course, should be closing when starting cold.)

Can you confirm if the choke butterfly is working (closing) when activated (or not)


Re:" no leak without choke". I have no idea, doesn't make sense to me...

I'd address the choke /cold start (or lack of) as that sounds like a definite issue, then tackle the leak (if it continues)..



.

This engine has no choke solenoid. Manual choke and start.

I will post a video of the fuel "leak" next time I work on the engine.

[panasonic]

It could be your float set to low when looking at it with bowl off and carb upside down. That is if it has an adjustable float.

Meaning to high a fuel level in the bowl. When you try to start with choke on it pulls to much fuel making it hard to start and leak fuel out the carb throat.

Once engine starts it can overcome this bit of excess fuel, and probably run a bit rich.

Like I said I don't know if it has an adjustable float or not....have a look.