Winterizing the VST on Yamaha HPDI and 4-Stroke motors

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DaleH

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FYI:

Just received this tidbit of info from one of our esteemed members here, TomS, in regards to winterizing the VST (Vapor Separator Tank) on the newer Yamaha OBs:

"I didn't do anything special for my VST. I just stabilized the fuel and ran the engine long enough to ensure that the VST was full of stabilized fuel.

I'm basically leaving the VST tank full of fuel. I've heard of people having problems when the vst pump is allowed to run dry, and also to avoid any corrosion on this expensive part that may occur if it is stored dry.

In the Spring, I will drain out all the old fuel out of the VST, clean the filter, replace the gasket, and start it back up with some fresh gas."


Hope this helps others ...
 
I've left my VST tank full for the past 5 years without incident. The fuel is stabilized with Pri-G stabilizer.

I do not drain it in the spring.
 
Well, since I'm the anonymous source of the above info :roll:

I'll clarify that the only reason I'm draining the VST is so that I can clean/inspect the VST filter, just to make sure its in good shape at the start of the season.

-- Tom
 
Just finished processing my F150. Spoke to the local Yamaha mechanic and he recommenced draining the VST. No big deal on the F150 although if the fuel is stabilized I don't know why you have to. Did it anyway.
You folks who have checked the filter did you find anything clogged. With a 10 micron Raycor as the primary filter followed by the engine mounted filted do you really run the risk of the VST filter plugging?


ray
 
The red ring is a water indicator in the primary engine base filter. When water is in the bowl it will start to float or it should. A lot of time the ring expands slightly and falls off the white plastic guide on the fuel filter and then will jam. I was told this is common with etanol and to slightly bend the two guides outward. Be cateful because you can snap the plastic and there goes $25. Hopefully you have a good fuel water seperator before the engine filter because if water gets as far as the engine filter you may have the start of some serious fuel problems. I like the Racorfuel water seperators with the clear bowl which allows you to check each time the boat is used.

Now for the Vapor Separator Tank VST. I just finished winterizing my F150. Nothing was indicated in the owners manual about the VST. But one of the previous posting about draining the VST caught my interests. The local Yamaha Mechanic definately recommended it and Yamaha susequently sent me their 2006 Marine Tech Guide-General Tech Tips on Off Season Storage....page 1-29 DRAIN THE VST...." Gasoline left in the VST for prolonged periods of time will break down and possibly cause the electric fuel pump to stick". This statement was right after the recommendation to stabilize the fuel which raises the question why do you have to drain if you stabilize. In any event it takes maybe 10 minutes to drain the VST so why not. If you do drain then MAKE SURE in the spring you use the primer bulb to prime the system so you avoid running the fuel pump dry even for a few seconds.

I think the vst filter in question is the one on the electric fuel pump which is located within the VST. At least that is what the Service Manual shows. If you are going to drain the tank send me a note and I'll be glad to walk you through it
hope this helps

Ray
 
rplas48":188yrtnn said:
2006 Marine Tech Guide-General Tech Tips on Off Season Storage....page 1-29 DRAIN THE VST...." Gasoline left in the VST for prolonged periods of time will break down and possibly cause the electric fuel pump to stick". This statement was right after the recommendation to stabilize the fuel ...
Thanks for posting that Ray.

What get me is that fuel "breaks down" by oxidizing. To do so, it need exposure to the air. If you leave something full of 'treated fuel', there's no air space, or very little in relation, so there won't be too much oxidation, if any.

But by draining a tank dry ... now one leaves the entire tank volume of air to oxidize what little fuel might be in there ... treated or not. Now I don't run these motors, but I kinda like TomS's info to treat and leave full, but drain in the Spring. The info he got also said it could corrode if not left full.

I tell ya' ... this is a ton of info out in regards to the E10 fuel and much of it contradicts other viewpoints.
 
rplas48":2cd61s9n said:
The red ring is a water indicator in the primary engine base filter...Now for the Vapor Separator Tank VST. I just finished winterizing my F150...I think the vst filter in question is the one on the electric fuel pump which is located within the VST. At least that is what the Service Manual shows...

So the little tubular clear bowl with a filter and red ring is not the VST. What is the VST, where is it, and what is its purpose? Do you have a pic, or a # from the Yami parts manual/diagram?
 
DaleH":1ex30mmn said:
I tell ya' ... this is a ton of info out in regards to the E10 fuel and much of it contradicts other viewpoints.

You've got that right brother! :shock:
It's all a moving target. :roll:
 
Go to yamaha's web site and look at parts and service header. Enter info for the F115. Go to fuel injector pump. I believe the filter is right under the pump...item #8 68V-13915-00-00. The VST is what the pump is housed in at least that is what it is called on the F150. The drain plug is #14. On the F150 it is on the starboard side, mid way, down low and has a clear hose connected to it allowing for easy drainage.

If you haven't had any fuel problems and have a good fuel water separator I'd wait to see what the guys have to say when they pull their filter. Haven't worked on one of these so I don't know how involved it is. My engine is a 2006 so I hope I don't have to for some time.

Ray
 
Thanks.

I have the large clear-bowl 10 micron RACOR filters/separators...one for each motor...in the bilge well ahead of the filter on the motor. Converted to E-10 about mid summer and have not had a bit of water or crud in the filters to this point.
 
Good and the Racor should stop any water before it gets to the engine filters . Hope that when the other folks pull their VST filters they post what they found.

Ray
 
VERY old thread, but it is relevant to my issue. My 2014 F115 was running like a top in the fall. I stabilized it AND I ran the yamaha fogging oil in the gas. On spring startup the vst was overpressurizing and pumping out fuel via the carbon canister. Turns out the VST float had cracked and filled with fuel. The fuel had a real blue color which looks just like the fogging oil. I did not drain the vst.

Did the fuel in the VST freeze and break the float? Does the fogging oil freeze? I know fuel doesn't. I just never heard of the float cracking.
 
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