Yamaha 9.9 solenoid fails

[Richard Harper]

I have had the same failure several times now, every 2-4 years. When starting, the solenoid will click and the starter will rotate a fraction of a turn. After several or many attempts, the starter works and the engine starts.
The voltage at the starter shows that it is the solenoid that is not working properly.
Has anyone else seen this problem and is there any solution other than to have spare solenoids ($60 wow) on hand?
Thanks

[Bean Counter]

Had similar issues on previous boat, and other electric start outboards on runabouts. Regular spraying with WD 40 or CRC seem to make this and other components last a fair bit longer. The problem with outboards hung under cats is that there is a lot of salty dampness down there. They do not sit in the sun and dry out. Just my experience.

[a64pilot]

Usually a solenoid that fails in the manner you describe, fails due to burnt contacts inside of the solenoid. The solenoid is still working just fine, but the burnt points won’t conduct enough power to do the job.
Many years ago they could be disassembled and the contacts filed, that would last a little while but not long because the coating that helps prevent arcing was worn off.

If it’s failing like I think it is, there is no fix, other than installing a larger solenoid with contact points that can carry more current.

So, pretty much carry a $60 spare or two. If your in the Bahamas or similar and have to pay to have one flown in, pay import duties etc., that $60 easily becomes $200 and you stuck for a week or more.

Spraying a good rust preventative can’t hurt, is good for other things, but I doubt it will help the solenoid.
My favorite is Corrosion-X. WD-40 is pretty much useless as a corrosion preventative in my opinion.

[Rapanui]

Had one for many years which occasionally did this. Grease the the gear and all moving parts that move the starter motor pinion to engage the flywheel gear with marine waterproof grease.

[Parttime Sailor]

I had the same symptoms on my 1999 Yamaha 9.9. The problem was a loose connection in the power cables from the battery to the engine where they passed through a bulkhead. The voltmeter showed full voltage at the engine, but the connection was too high of resistance and not enough current was available. I tightened the connection and never had the problem again.

Yamaha has sold a bazillion of these engines. I think it is unlikely that the solenoid is too small.

[jacktheflyer]

Originally Posted by a64pilot

Usually a solenoid that fails in the manner you describe, fails due to burnt contacts inside of the solenoid. The solenoid is still working just fine, but the burnt points won’t conduct enough power to do the job.
.

This can be caused by a battery at the end of its life. When the starter is engaged the battery voltage drops to less than 10V and the current increases to compensate for loss in magnetic reactance.

[GordMay]

Greetings and welcome aboard the CF, Parttime Sailor.