Yamaha 90 2 stroke alarm sounding

[mr2stroke]

Hi all

I have a problem where at full throttle after a minute or so the alarm sounds
and the motor goes into idle mode for like 30 seconds, comes right and is able go again. im not sure as to what the problem could be. the motor has just been serviced by a Yamaha dealership impeller changed and a few other things.

Im not so experienced when it comes to these motors but I wouldn't think it was overheating as the pisser at the back, the water is always rushing out but very cool ? would anyone know what this alarm sound could be.

1 more thing: it runs all day at 3/4 throttle its just at full throttle the alarm sounds.

[ausnoelm]

Just guessing, I would say the water passages are near blocked, pretty common thing, you will need to remove the head and any covers you can to clean them out, then drill out the bolts you broke removing parts.

[mr2stroke]

this would be last resort im hoping. but wouldn't the pisser water be hot if it were overheating?

[ausnoelm]

No....It is a common problem.

[scofflaw]

I had exact symptoms on 94 2 stroke. T stats looked good, pump change, pressure valve good. passages loaded with crap. Gave it a 10 minute soak in muriatic acid, flushed it, and all was well after that. A lot easier than pulling the heads, and not much to lose.

[boscoe99]

A 90 two strokee won't connect to YDIS.

Solo, is Andy giving you a commission for pushing the product?

[mr2stroke]

I had exact symptoms on 94 2 stroke. T stats looked good, pump change, pressure valve good. passages loaded with crap. Gave it a 10 minute soak in muriatic acid, flushed it, and all was well after that. A lot easier than pulling the heads, and not much to lose.

Hi Scofflaw im very interested to try your method first, could you explain your process about "soaking". how did you do it?

Its a 1999 model

Thanks all !

[ausnoelm]

Don't think I would be too thrilled about soaking my alloy motor in acid, but it's your call.

[rodbolt17]

back in the day when merc used chrome cylinders.

we used muratic acid to eat off the aluminium left when a piston burned.

eats AL wont eat chrome.

be careful with it.

[scofflaw]

Hi Scofflaw im very interested to try your method first, could you explain your process about "soaking". how did you do it?

Its a 1999 model

Thanks all !

Stats out, lower unit off. Pour acid into stat openings with funnel.

Repeat for about 10 minutes, flush immediately after with garden hose.

[throrope]

I had exact symptoms on 94 2 stroke. T stats looked good, pump change, pressure valve good. passages loaded with crap. Gave it a 10 minute soak in muriatic acid, flushed it, and all was well after that. A lot easier than pulling the heads, and not much to lose.

***! That's awesome advice. Definitely a cost effective solution if it works and if not, little expense for better knowledge. Thanks

[ausnoelm]

Don't know how cost effective it will be if/when it eats a hole in the block! But as I said, it's your call, either fix it properly, or try the "easy" possible options, that may work, and may also cause major damage.

[robert graham]

Any acid or chemical treatment for deposit removal must be circulated through the motor....not poured on it or in it.....a 55 gallon drum of water would be a good place to start...run motor in drum and then add acid/chemicals under very con*****ed conditions....