90HP Yamaha won't plane my C-Dory 22

Someone earlier suggested connecting a known good fuel source directly up to the motor. Like a 6 gallon tank. Have you tried that? If so, sorry, I missed it.

Charlie
 
You certainly can try the different fuel source--and that is the cheapest and easiest.

Since you already spent some considerable coin for this motor, I would think that the shop should stand behind it. Hopefully they missed something (or maybe didn't do as good as a job as you paid for?)
Did you personally change the pick up screen, and clean the tank? It could take just one little bit of stuff to cause a problem.

I don't know much about the Vapor Separator/High Pressure fuel pump, in that specific outboard, but if Marc says that could be an issue, he is a man who knows those motors! The injectors and injector pumps have to have clean fuel, or there can be issues. Even if cleaned, and one place was missed, then contaminated fuel got down the line, it could now be a problem.

The fact the boat seemed to run well the first for hours, suggests that something was picked up, and is now down the line in the fuel system.

Since you are not getting enough power to plane, at 3800--this certainly rules out the spun hub. I assume that you did pull the plugs, checked the gap and condition.

Good luck--and keep us all in the loop.
 
One question remains unanswered - is it firing on all cylinders?

Begin with a cold motor - take the cowl off - start the motor (either on the water, or on the muffs) - as the motor is warming up, touch your hand to the motor on each cylinder (near the spark plugs works) - are all cylinders heating up the same relative to each other? (You can also do the same with an infrared thermometer if you have access to one...)
 
AK Angler":4xhrq9f3 said:
One question remains unanswered - is it firing on all cylinders?

Begin with a cold motor - take the cowl off - start the motor (either on the water, or on the muffs) - as the motor is warming up, touch your hand to the motor on each cylinder (near the spark plugs works) - are all cylinders heating up the same relative to each other? (You can also do the same with an infrared thermometer if you have access to one...)
Click to expand...

one of these are handy

http://www.summitracing.com/parts/rnb-8 ... MgodrjUA1Q
 
Making fire in an internal combustion takes fuel/air, compression, and spark, all properly timed. Checking for even cylinder temps as the motor is warming up will indicate if there's fire in all cylinders. If one is cold, then you can check for spark. (Using a tool like BrentB linked to makes that easy, but it's not an absolute necessity.) If you have spark on the cold cylinder, check for even compression between cylinders. If you have spark, and good compression on a cold cylinder, the problem almost has to be an issue with fuel delivery. Pretty simple to diagnose, actually...
 
Finally the motor problem is fixed!!! Problem was rusted VST pump and plugged VST filter. Had to put motor in shop to replace the pump and they also changed filter. Of course, warranty didn't cover anything since it was fuel related. Don't know what the previous owner tried to run this motor on, but it wasn't good gas. Before I put the motor in the shop, I replaced the water separator filter with a 2 micron filter. I believe this will help prevent future problems. Motor now runs like it should and boat planes quickly. Thanks to all for their help. I just wanted to follow up to let you all know all is well with the C-Dog.
 
Great that it is fixed! Do you have a 10 micron filter before the 2 micron?

It may cut down on the filter changes.

Try and always run on non ethanol gas if possible. I know MS is enlightened--and 333 "pure gas" stations..
 
I always like to read "how it all turned out." Thanks for posting.

I don't know that much about outboards, and even on inboards there are people who have differing theories on filtration, but one that I tend to believe, at least for inboard engines (because the person from whom I received the info is knowledgeable) is that if you only use a very small filter (such as 2 micron), then it's actually counterproductive because larger particles can "punch" their way through the filter. So if only one filter 10 micron may be better (of course if you have a 10 followed by a 2 then that's different).
 
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