Coating for the inside of the VST

[Hpracer]

The moderator closed my previous thread on this subject because it got onto a contentious debate about Ethanol in Marine engines. Because of this I was unable to get any suggestions about what if anything could be used to coat the inside of a VST that had experienced the early signs of corrosion due to getting water in the fuel, and the resulting acidic or galvanic attack on the inside of the tank. These flakes of metal clog the small filter screen of the high pressure fuel pump and keep the motor from running at WOT. Getting at this filter screen is not an easy job and I would like to not have to do it again.

​Does anyone know of a coating that would be impervious to fuel and could seal the inside of the tank and guard against this condition?

 

[Faztbullet]

This might as I use it on my go-kart and ATV tank. Have one that going on 4 yrs and no leaks or particles in fuel filter....

https://www.kbs-coatings.com/cycle-tank-sealer-kit.html

 

[hemi rt]

Why not remove the tank and replace it with an aluminum or plastic tank.

 

[Faztbullet]

The VST is aluminum......

 

[jerryjerry05]

They even make a VST tank in plastic?
​I think the pressure in the tank might preclude plastic.
OR get a new one.
Used on e-bay.
​It always helps if you mention what motor were working on?

 

[Chris1956]

Gee, use some fine sandpaper to remove the loose particles and clean it out. Now make sure your water separator is working and keep the water out of it.

 

[Scott Danforth]

buy used VST tank off of ebay, send out for hard anodizing, fix your fuel/water separator issue and go boating

 

[bruceb58]

Like Scott said, keep the water out of your fuel. You assumed it was ethanol that is causing the corrosion which it isn't.

What are you experiencing that makes you think you are getting a clogged screen? Have any pictures that you can show?

When you clean this screen does it make your engine run normal at WOT?

EDIT: Looked at your previous posts. you have a 2001 Mercury 115. What ave you replaced? Have you replaced the 2 filters on the engine before including the cartridge for the water separator filter?

 

[dingbat]

If this is a Yama-merc, Yamaha recommends the use of a 5 micron seperator filter to minimize problems with VST screens.

 

[bruceb58]

I have a 2006 Merc 90 which is the Yama-Merc. I am religious in replacing the small water separator cartridge in the filter holder that is inside the engine cowl. According to Mercury, an external water separator filter is not recommended as it could reduce proper fuel flow.

 

[dingbat]

According to Mercury, an external water separator filter is not recommended as it could reduce proper fuel flow.

The key word here is "could".

The small Racor separator filters rated at 30 gph will give you a pressure drop of less than 0.1 PSI at your max. flow of 12 gallon per hour. Betting your small in-line filter is more restrictive than that.

I was incorrect about the 5 micron filter, It's actually a 2 micron filter.

Don't know anything about a 90HP. The guys running 150HP and up HPDI are running 2 micron filters behind a 10 to keep the VST clean. Easier to replace a filter a couple of times a year than clean a VST or worst yet, clog an injector and blow the motor.

 

[bruceb58]

dingbat Thanks. I will look into that myself.

Is that what you are running on your engine? Does your engine have the cam driven lift pump before it goes to the VST?

 

[dingbat]

dingbat Thanks. I will look into that myself.

Is that what you are running on your engine? Does your engine have the cam driven lift pump before it goes to the VST?

I use a Racor 10 um S3214 filter on my personal boat (carbed)

I run a Hydra-sport Vector with twin150 HPDI for a guy from time to time. He runs the 10/2 I'm combo on that

 

[Hpracer]

Thank you for the information about the coating for the VST tank and the suggestion to get it hard anodized. I would be interested if someone has actually done that (anodizing) and it solved the problem.

​To the other people who have been good enough to suggest solutions, I am not sure that you understand the problem. I do run a 10 micron external water separator and change it religiously, sometimes twice a year. The internal little visual filter/separator inside the cover never shows any water. The problem in my situation is caused, as I have been told by the local marina, by fuel that has dissolved water in it sitting in the VST and attacking the inside of the tank, causing flakes that clog the very small (undersize) filter on the inlet to the high pressure pump. No filter leading up to the VST will help a situation where the flakes come from inside the VST, since it would be after any such filter.

​Maybe they make better water separators than what I use. I have one of those Rancor type Sierra 10 micron external filters that is supposed to separate water. The marina tech people tell me it is the dissolved water that creates an acidic condition and that causes the corrosion and flaking off of the inside of the VST. And with the screen to the fuel pump being so small it doesn't take much to partially clog it and keep it from going to WOT. Will water separators take dissolved water out of the fuel or just the undissolved variety?

 

[hemi rt]

I don't think there is a water separator that is normally available to the general public that will remove suspended moisture from gasoline. If the gasoline sits the water will eventually separate but seeing most fuels now have ethanol mixed in this would make the separation just about impossible. You may get phase separation with ethanol fuels with the water staying with the ethanol though. If this is causing your problems then I would look at a different place to purchase your fuel

 

[jakedaawg]

Why not replace the vst? Just curious.

How many times has this happened? I take care of a lot of outboards and have had a few failures over the years but of all the vst/high pressure fuel pumps none have ever had corrosion or the fine filter filter be the contributing cause to the failure. It has always been the pump itself or the integral pressure regulator depending on make, model and so forth.

 

[Hpracer]

No Title

Why not replace the vst? Just curious.

How many times has this happened? .

I replaced the VST the first time this happened. I brought it to the local marina and $1500 later I hoped it would never happen again. The VST is about $350 alone as a part. The second time it happened I took it all apart myself and, thinking that there must be a lot of crap in the VST, cleaned it out and had the injectors cleaned. I took a picture (below) of the inside of the VST thinking that it would show that it was clean, When it happened for the third time I went back to the marina and showed them the picture and they pointed out that the small spots at the bottom of the tank were in fact corrosion, and that was all that was needed to cause a problem because the screen to the pump is so small.

​I haven't done the job for the third time because I want to do it once and for all, if that is possible. I think I may have mentioned that the mechanic at the marina has the same motor that I have, and because he does a lot of fishing pretty far out, and doesn't want to have trouble, takes his motor apart and cleans the screen three times a year. You can be pretty sure that if there was some way around this he would be doing it.

​I am surprised that more people aren't having this problem. I laugh when some say just use good fuel and a separator and you won't have any problem. Maybe other states sell gas without Ethanol, but that is not the case in Massachusetts, even at the marinas. This marina has added this job to the PM list for all of their customers.

 

[jakedaawg]

So, are you using a fuel additive? That does not look as much like corrosion to me as it does the effects of Stabil.

 

[Watermann]

One option would be POR-15 tank sealer, there's a kit you can buy to clean and prime the inside of the tank before application of the sealer.

http://www.por15.com/POR-15-Fuel-Tank-Repair-Kit_p_62.html

 

[Hpracer]

One option would be POR-15 tank sealer, there's a kit you can buy to clean and prime the inside of the tank before application of the sealer.

http://www.por15.com/POR-15-Fuel-Tank-Repair-Kit_p_62.html

​Thanks - I have asked them whether that product would work on the inside of an aluminum tank.