F225 VST filter & fuel pressure

[dkg]

I have a 2006 Yamaha F225 with only 15 hours on it. When I put it in the water this season, I have a problem of it losing power when accelerating right around 3800 RPM. If I carefully feather the throttle, I can get the boat up on plane and past that apparent limit. The motor ran great last year (during break-in and after). It seems to run fine now except when I try to accelerate to full speed.

This is a consistent problem. I have checked the fuel lines and replace the sep filter and blew out the fuel intake in the tank thinking there might be a restriction with no change in performance.

I have been reading the forums and some of the symptoms sound like I probably need to clean the VST filter (after only 15 hours???). However, I first checked the fuel pressure while running the motor through the problem acceleration and it is a constant 40psi on the rail.

So with good fuel pressure is it still possible this symptom can be caused by the VST filter?

The only other change on the boat for this season is that I replaced the main electrical harness (the 23 year old harness had developed an open on a critical wire -- power to the ignition switch and gauges). I can't imagine the new harness could cause the motor to behave this way but if anyone thinks it could let me know.

The only other test I just thought of was to hook in a 6 gal tank and use "newer" fuel to see if the problem goes away.

Any thoughts would be appreciated.

Thanks,
Dave G.

 

[dkg]

Re: F225 VST filter & fuel pressure

I just ran the motor for a while on a shop tank with fresh fuel. It seems to behave a little better. However, I still have that spot of the acceleration where the power plateaus or drops. If I slowly back off on the throttle there is a point where it suddenly has more power and can accelerate past that point.

Still hoping someone can suggest what I should look at next.

Thanks,
Dave G.

 

[rodbolt]

Re: F225 VST filter & fuel pressure

next step is to test rail pressure and clean the injector screens.
typically with 4 year old motors with that low hour count we see bad fuel systems.
any fuel in the boat over 6 months old should be pumped out and disposed of.
that engine has no knock detect system.

 

[dkg]

Re: F225 VST filter & fuel pressure

As mentioned in original post, rail pressure was tested and it was a constant 40psi through the whole run. The original question was, if the pressure is good, can I assume then that the filters are clean?

Although this is a 2006 motor, it was in a warehouse new in crate until last year. The low hours is because the boat was repowered last summer -- I have a full 3 year warranty starting last summer.

 

[rodbolt]

Re: F225 VST filter & fuel pressure

if rail pressure is good then its most likly stopped up injector filters.
could be a failing TPS but if its still under warrenty take it in.
most fuel issues are NOT warrenty.
defective materiels or workmanship are warrenty,bad gas aint.

 

[dkg]

Re: F225 VST filter & fuel pressure

if rail pressure is good then its most likly stopped up injector filters.
could be a failing TPS but if its still under warrenty take it in.
most fuel issues are NOT warrenty.
defective materiels or workmanship are warrenty,bad gas aint.

Thanks for the info Rod.

I understand fuel issues are not warranty -- that is why I was asking for input on the forums. Nearest authorized Yamaha service is over 100 miles away on rough roads. So I am trying to eliminate non-warranty issues before making that trip.

 

[rodbolt]

Re: F225 VST filter & fuel pressure

I know, its a bummer.
but most issues we have with that engine are fuel
you can try back flushing the injectors or sending them to flagship marine,or any injector shop local to you, and retesting.
I also test spark plug fireing KV.
its amazing if one plug fails it drops about 1000 RPM.
depending on what failed it can take out 2 cylinders.

 

[rib4charter]

Re: F225 VST filter & fuel pressure

It sounds like you have the same issue I am battling. I replaced my vst tank because the tech told me it was corroded and the filter was clogged withthe corrosion. When I went to throttle up I couldn't go over 3800 rpm just like yours on my 2004 F225. After I had the VST Tank replaced, I ran it for 10 hours and the filter just clogged again. This was after new fuel put in that was treated with Startron and ring free, and run through a 2 micron water separator fitler.

Before you chase any more ghosts in the machine, spend a couple of hours and check your VST filter by following these instructions.

http://www.simyamaha.com/category_s/1993.htm

Please document what the vst filter looks like before you clean it and what it looks like after you clean it. You don't need to buy a new one, just clean it it first with soap and water. Try soaking it first before using anything aggressive to clean it. If it is sodium sulfate it should dissolve in the water and the remaing deposits you will have to try something else as they may be other contaminents that were dissolved in the fuel that were released in the VST tank. If you can save a piece of the material clogging the filter please do before you clean it. If you can also save a sample of the fuel in your tank that would be great, to have for future reference on the ethanol and water content in the fuel (make sure it is a sealed class container) Please record any fuel additives you are using and what sort of water separator you are using and its micron rating. My sense is this is a huge problem that is being mis diagnosed by a lot of mechanics and yamaha needs to address this issue as I don't think these engines can run ethanol fuel at all even though they say they can run ethanol e-10. I am talking to a few people having this same issue. Your engine having only a few hours on it would be another clear example that the particles clogging the VST tank filter are being created by the fuel breaking down in the VST tank due to the excess heat inside the VST tank. Please message me with what you find out. I am going to be doing the same thing next week to mine, again as it just clogged.

 

[dkg]

Re: F225 VST filter & fuel pressure

Thank you for responding but I wish I had gotten this information yesterday

I just spent yesterday delivering the boat to a Yamaha certified service center to look at the problem. Not yet having a service manual, not knowing about the online guides for specific maintenance tasks like the VST filter replacement, and thinking that with so few hours on the motor it might be a warranty issue, I made the decision to bite the bullet and suffer the 3 hour trip each way over lousy roads

I'll let you know what they find. And if it acts up again, I'll certainly follow your advise.

Thanks again for the help.

Dave G.

 

[rib4charter]

Re: F225 VST filter & fuel pressure

Make sure you verify what they are going to check and what it will cost you. Diagnostic work isn't always covered by the warranty, only parts and the labor to replace the part. Make sure you mention the VST tank issue and have them check it. See if they can send you pictures if you are 3 hours away.

 

[rodbolt]

Re: F225 VST filter & fuel pressure

bad fuel isnt warrenty.
its just bad fuel.
VST maint is just that,maint.
best thing is to keep clean fresh fuel and turn it over completly at least every 3 months.
if you treated your car like your boat you would walk a lot more.
cars have sealed fuel systems that are not constantly vented to the atmosphere,most boats have a 5/8ths vent line directly to the outside air.
E fuels will absorb water from the humidity in the air.
most boats tend to operate in a humid environment.
once the Efuel has sucked up all it can the water and ethanol seperate from the gas and the nasty begins.
ONLY solution at this point is drain and clean the tank,replace all lines and clean the engines fuel system and dont let it happen again.
let your fuel lines dry overnight after removing them,shine a light down the line.
if you see any yelowish stuff on the line its time for replacement.
that yellow stuff will redissolve and reclog the VST and injector filters rapidly.
its NOT a yamaha,suzuki,mercury or BRP problem.
its stupid gubbermint.