Self clogging f115 VST?

[UncleDirtnap]

Hey all -

Last year I bought my sister's old deck boat. It had been maintained perfectly by the original owner, but she had some health issues and had let it sit for 2 years.

It didn't take too much to get back on the water- I redid all the normal maintenance things, filters, etc. I had a hard time getting it past 3000 rpm for a month or 2, but some reading on the forum led to the VSP. It was fairly oxidized inside, nice and chalky, and the filter was clogged. I cleaned it up with some copper brushes, new filter, cleaned out the injectors and she ran like new.

A week later my friend borrowed it for his boyscout troop island campout and sank it. Ahem...buy me a beer and I'll tell you all about it.

Some better friends and I had her up and home 6 hours later, and I go through every engine saving strategy I can find. It had gotten wet in the hood (top part didn't go all the way under, but close) and there was salt water in the inline filter. Drain all the gas, drain the VST, replace all the filters... It all pays off - she starts perfect and still runs like a champ with one problem-

After about 30 minutes (sometimes longer, sometimes sooner) the top RPMs stop dropping, until I am crawling back down the channel at 1900 RPM. It's always the VST filter. I have a 10 micron filter on the firewall, and new filter inside the hood (clamp on inline instead of the original yamaha), and the gas looks pristine. I have sprayed out the fuel manifold and changed all the lines. It has happened 4 times now-

The VST filter is always clogged with a white powder. Inside the VST it looks chalky, and there is some corrosion on the surface of the pump inside. I have tried a handful of things- I've used scotchbrite, copper brushes, and steel wool on the pump and the inside of the VST. Once I even filled the bottom half of the tank with vinegar, hoping that the mild acid would exorcize my demons. Nothing seems to help for very long - I go for a test run, it works great, then less great, then barely there at all.

Any advice? It seems that other folks with VST issues seem to have tracked it down to ethanol, so I may be on the wrong track. I started getting her ready for service again, and I would love to finally put and end to this particular problem.

Thanks for your advice!
-rj

[cpostis]

UncleDirtnap:
I had the the same problem "white powder" clogging the VST filter when I first ran my new used boat. After three times finding the "white Powder" clogging the filter, I checked my fuel lines. I found the same "white powder" on the interior lining within the fuel line hoses from the tank to the fuel filter/water separator. Some others have reported that the linings in their hose have deteriorated and "brown bits" broke free and clogged fuel systems. I suspected "ethanol issues" used by the previous owner. I replaced with fuel lines to a good quality marine fuel hose that is compatible/rated for ethanol blends to 15%. I used Goodyear/Novaflex 360-09. No problems since. However, you should access your fuel tank and peek in to see if the surfaces are "nice and shinny, mine were. I always use non-ethanol gasoline.

[fairdeal]

It was fairly oxidized inside, nice and chalky,

...and sank it....and there was salt water in the inline filter.

The VST filter is always clogged with a white powder. Inside the VST it looks chalky....

I'm thinking the "white powder" comes from corrosion of aluminum surfaces -

brought on either/and/or by E-10 and seawater.

Sounds like the anodizing of the interior of the VST has been stripped - that can't help.
Who knows what the inner surface of the fuel rail and fuel cooler look like.

And, possibly, by far the largest surface area - do you have an aluminum fuel tank?

(btw I'm unable to imagine how saltwater got into the "inline filter" even if the boat sank...)

What to do about it? I doubt filtration is the answer,
"salts" could pass right through even 2 micron,
and then settle out upon sitting in the VST...

A tough problem.

[DennisG01]

The boat sank, but no water entered the fuel tank? How did you verify the fuel quality was/is good?

Re-plumb the engine with a portable tank (and new hose) and use that for a while. It'll be a little cumbersome, but keep a jerry can, or two, onboard for extra fuel. If all goes well with that, then you know the issue is in the lines or the tank. Which, of course, is most likely the issue, anyways.

[throrope]

I had repeat fuel issues after several runs through the carbs until I realized the fuel supply system was contaminated and I undid my work with the next key turn. Issues want away after replacing the tank and all hose and materials including the connector on the outboard.

Many materials are rated for 10% ethanol, but I haven't seen many rated for 100%, which can happen with phase separation typical of old fuel.

You may be struggling with damaged surfaces that continue to shed clutter and dissolve into your fuel. Also, boats often sit unused with little attention long before the decision is made to sell. Like our boat, you may be enduring much more than two years of inattention.

Since then I learned, while our Yamaha's materials are manufactured for ethanol, this very dependable system was engineered prior to ethanol fuels. I also ran 3/8" copper for fuel line to minimize hose to short lengths at the tank and outboard and change the hose every couple years. I pump all fuel from the boat, drain carb bowls and leave tanks open and upside down between trips. The boat hasn't been out much in the last two years and runs like a swarm of angry hornets every time.

[UncleDirtnap]

I wasn't very clear about this - there was LOTS of salt water in the tank. That was a miserable ordeal to handle. The tank is a plastic one - I can see it but can't remove/replace it without a sawzall and a new marriage. Every spare neighborhood gas can, along with a few buckets. Drain, let separate, remove water, repeat, then cycle the gas-ish stuff back into the tank, drain again. In the end I had a empty tank that had been flushed out pretty good. Left it open for a day or 2, put 5 gallons in, swished it around, and drained that out and put it in my daughters bulletproof volvo. I then filled the tank up halfway at the gas station. Hope that was enough-gas polisher folks wanted $500 to come out

Not sure how the inline filter had some water in it, but it did - not much, but you could see it separated out.

I replaced the hoses after I put everything back together- I need to cut an access hatch to change the fuel sender this weekend, and I'll take a flashlight and get a reading on the interior of the tank.

-rj

[fairdeal]

ahh - huge plus that its a plastic tank - IMO that eliminates much concern there.

Pardon me if the answer is already above -

since you've been having this problem,

have you been running E-10 - or "real" gasoline?

[99yam40]

Sounds like you did not drain the tank and lines ( fuel system) completely if you still have water showing up in filter, or you have water getting in from some where.

If you used the fuel pick up to drain the tank, it does not sit on the very bottom and cannot get all of the water out of a tank

[rodbolt17]

once E fuels are contaminated by water it is now trash fuel suitable for starting fires in the back forty.
not as an engine fuel.
if you are trying to reuse contaminated fuel your simply shooting at your toes.

[cpostis]

I wasn't very clear about this - there was LOTS of salt water in the tank. That was a miserable ordeal to handle. The tank is a plastic one - I can see it but can't remove/replace it without a sawzall and a new marriage. Every spare neighborhood gas can, along with a few buckets. Drain, let separate, remove water, repeat, then cycle the gas-ish stuff back into the tank, drain again. In the end I had a empty tank that had been flushed out pretty good. Left it open for a day or 2, put 5 gallons in, swished it around, and drained that out and put it in my daughters bulletproof volvo. I then filled the tank up halfway at the gas station. Hope that was enough-gas polisher folks wanted $500 to come out

Not sure how the inline filter had some water in it, but it did - not much, but you could see it separated out.

I replaced the hoses after I put everything back together- I need to cut an access hatch to change the fuel sender this weekend, and I'll take a flashlight and get a reading on the interior of the tank.

-rj

Uncle Dirt not reuse the contaminated fuel in his boat tank. He also said he had "a empty tank that had been flushed out pretty good", Said he replaced fuel lines after the flushing/cleaning. But, poor Volvo!

Make sure you flush your fuel lines (even though new) and change/clean fuel filters/and all portions of your fuel system again, like 99Yam says!
Now you say your VST filter is clogging repeatedly, I wonder about debris past the VST? Did you check/clean injectors? You might as well check that you have water flow through your fuel cooler (#13 in diagram) while you are at it. "Complete Fuel System Check/Clean".

F115.FuelInjection by Charles Postis, on Flickr

[boscoe99]

If the coating on the interior of the VST has been removed, and particularly if the interior of the VST has been scrubbed within anything copper, I suspect the VST is toast. Copper is death to aluminium. Copper will become embedded in the aluminum and start doing what copper does. Corroding aluminium.