Yammie Power Problems

[TomS]

Tim,

That is great news! Way to go and get it done on your own. Now you have that much more confidence you know what is happening inside your engine, and you have taken care of the major maintenance stuff that must be done to keep that engine going strong!

Did you mention anything to the mechanic about the VST filter that was broken off and rattling around inside your VST tank? That could have caused major problems. The pump sucks fuel through the guts of the motor itself, and could have done significant damage if a piece of plastic or whatever got lodged into the $800 pump.

The low pressure fuel pump with a tear in it is definitely bad, but that is the expected failure mode, and is why people say you have to change them all out every 2-3 years. It definitely contributed to your problems, as that tear meant you were only working on two out of three pumps and wouldn't have been able to keep the VST tank full of fuel at the higher RPMs and caused the surging we discussed in emails.

Thanks for posting the pic of the new VST filter, I haven't seen one before and wonder if this is Yamaha's attempt to deal with the Ethanol related issues a lot of people are having lately. With a lot more surface area, the filter can catch much more stuff without causing problems, and hopefully get it to the point where you don't have to clear it out mid-season.

Congrats again on getting it done right! Like I said before, a lot of guys just start swapping out parts, starting with the most common maint. items and hope for the best. Once they get to the end of the list they start mentioning the more expensive stuff.. I've never read of a Yamaha CPU going bad, and for $1200 that is a lot of money to be guessing with.

-- Tom

 

[TimC2520]

Agreed indeed Tom, thanks again for all your help.
I did not mention to him about the vst filter NOT being attached or the piece of o-ring floating around the bottom just waiting to get sucked up into that $$$$ pump. I was just disgusted and figured I'd leave well enough alone. I felt so satisfied knowing the job worked, was easy and I knew everything was put back in order. And the difference in smoothness and performance was unbelievable. I am going to check the manual again, but I think there is still one more fuel filter somewhere, no? I have a Racor water separator, then there is a screw off, canister under the cowling (with the red floating ring), the vst screen...and something tells me there may be 1 more? Also, I'm sure there is an oil filter I'll be looking for.
When I removed the new vst screen from the box and saw it was different than the one I wanted to replace...I thought, ugh-oh, that thing is the wrong part and will not fit.....but it fit nicely and I agree that has to at least double the filtering capability. Also, they have re-designed the gasket that fits between the block and the O2 sensor mount but I did not take a photo of that, sorry. The new exhaust tube said "re-designed to lengthen the life span of the sensor itself" but it looked the same to me.....but it was covered it carbon and black oily residue and I did not clean it off to see if it was any different from the new exhaut tube.
Lastly, I noticed my fuel hose and primer bulb, the section in front of the
motor that is exposed to salt, soap, sun, etc does not look good at all and I was going to change that section and put a new bulb in...Do you know off hand what size OEM fuel hoses are?

 

[TomS]

On the fuel line/primer bulb, I don't know, but I noticed the same on my 1999 when I did the 100hr service a few weeks ago. Definitely a project for this fall or next spring.

I've seen the redesigned O2 sensor gasket, nothing too different that I can tell there.

The only oil filter that I am aware of is mounted to the external oil tank, behind the black metal piece on the side. Behind the metal cover is the remote oil pump and a small inline fuel filter that is very easy to change out.

Two other fuel filters I can think of (but haven't yet checked them myself).. one is the screen that mounts between the fuel pressure regulator and the VST tank. The other are the filters that are mounted inline with each of the fuel injectors. I think there is a pic of the injector filters on that other post I referenced, with 6 green filters that look like thimbles.

-- Tom

 

[TimC2520]

Thanks again.