Outboard Blues

[Alan de Enfield]

29 minutes ago, bigfatmatt said:

Engine will now start and run in neutral or in low revs, if I try to push her to higher revs even warm she cuts out. Thinking I need to find a Yamaha outboard specialist at this point. Thanks for suggestions.

 

 

To me that exactly describes a 'main jet' problem. The tickover jet is working but when there is a demand for more fuel (higher revs) a blocked / broken main jet will not supply fuel and the engine will stall.

 

NORMALLY, if you drop the fuel bowl down and remove the float the main jet is directly above where the float sits.

I had the same in one of mine and it was simply a 'globule' of water stuck in the main jet.

[bigfatmatt]

I ran carb cleaner (the stuff that comes in an aerosol can) through the jet, it was spraying properly out of all of the holes.

Edited July 20, 2023 by bigfatmatt

[Mad Harold]

I think you will have to strip the carb to check it properly.

Old petrol turns into a brown gungey jelly and it may be that a blob or two is blocking a jet or perhaps the needle valve (that lets fuel into the float chamber) or even prevents the float from operating properly.

If you havn't stripped a diddy outboard carb before, take some photos as you are doing it to help re-assembly.

I almost forgot.Spread a cloth underneath the carb just in case you drop a screw or something.

Stuff falling inside the outboard leg can prove well nigh impossible to retrieve!

Don't ask me how I know this! 😞

 

Edited July 20, 2023 by Mad Harold

[Dockeroo]

Does the prop turn freely in neutral when the engine is off? You should be able to turn by hand.

 

My outboard had a seized propeller and done this exact same thing, i had to gove.it a bash with a runner mallet.

[bigfatmatt]

On 20/07/2023 at 13:29, Mad Harold said:

I think you will have to strip the carb to check it properly.

Old petrol turns into a brown gungey jelly and it may be that a blob or two is blocking a jet or perhaps the needle valve (that lets fuel into the float chamber) or even prevents the float from operating properly.

If you havn't stripped a diddy outboard carb before, take some photos as you are doing it to help re-assembly.

I almost forgot.Spread a cloth underneath the carb just in case you drop a screw or something.

Stuff falling inside the outboard leg can prove well nigh impossible to retrieve!

Don't ask me how I know this! 😞

 

Yeah this is my thinking, I stripped the part with the jets in and cleaned that out, took the jets out and cleaned them separately, but might need to strip it down entirely and get it in an ultrasonic cleaner.

On 20/07/2023 at 17:27, Dockeroo said:

Does the prop turn freely in neutral when the engine is off? You should be able to turn by hand.

 

My outboard had a seized propeller and done this exact same thing, i had to gove.it a bash with a runner mallet.

Prop turns freely yeah.

Edited July 22, 2023 by bigfatmatt