1989 40 HP3 cyl kills @ WOT

[seesaintleo]

I have a 1989 40 HP that kills @ WOT after traveling about 1/2 mile. Have not determined if losing spark or fuel. Will restart, but turns over very slowly. Like the battery is, or almost dead. When problem first started it would immediately restart with no hesitation. Will ***** all day long. Waterpump seems to work good.(New). Carbs have been cleaned. Timing and linkeage all adjusted according to factory specs. Any thoughts???

[ausnoelm]

Need to do some basic trouble shooting when it stops, how were the carbs cleaned

[TownsendsFJR1300]

With it re-cranking VERY SLOWLY, check you battery voltage.

Also check the voltage at the starter when cranking slowly.

If the electrical system isn't charging enough, especially at WOT,
you could be loosing spark.

[99yam40]

loss of all fuel or spark that kills a motor while running at high RPM is not common.

hard to turn over could be the motor seizing up or the lower unit seizing.

check lower unit lube for metal and inspect the cylinders with a bore scope.
I would say to run it without the cowling and flywheel cover on so you can feel how hard the flywheel is to turn after it dies, but that will do even more damage to it if it is seizing up.
Test your alarm system, if it is not working the motor could be overheating and you do not know it. just some things to check on.

[throrope]

I concur with the above.

If your lucky you have a bad electrical connection that gets hot with use. Marine environments exaspirate the problem. With heat, resistance increases causing a voltage drop that acts similar to a low battery. When cooled, the problem appears to disappear. Ground connections are the buggers because they're often the last found and cheapest to fix. These problems are simple to fix; however they can cause conequential stress and failure of batteries, magneto, starter, etc.

Engines on their way to seize act similar to a bad or low battery due to the increasing internal friction. Caught early they are expensive to repair. When seized become expensive to replace.

Both issues often escalate quickly and can leave you dead in the water exactly at the worse possible moment. I suggest resolving yours before the next trip.

[seesaintleo]

89 40 hp Yamaha killing

When this stalling issue first started,the motor would immediately restart with no hesitation. The hard restart condition is a new condition that happened after linkage and idle were adjusted.

[TownsendsFJR1300]

Sounds like the linkage adjustments need to be re-checked and adjusted.

It also sounds like two different issues...

[99yam40]

turning over slowly will not be because of adjusting linkage and idle

[TownsendsFJR1300]

turning over slowly will not be because of adjusting linkage and idle

That's why I posted it sounds like two different issues...

[seesaintleo]

89 40 hp Yamaha killing

thanks for the input from everybody.

[TownsendsFJR1300]

Please post back when you find the issue(s)....