VST Filter on '05 F115

[pilot4net]

I do not yet have a service manual for this motor. I am planning on ordering one this fall. I am having a little problem with sluggish throttle response and low top end rpms and want to check the VST filter on this motor. First of all I am new to outboard motors. I think I see the VST on my motor. On the port side of the motor, I see an rather long aluminum (looks like aluminum anyway) squared cylindrical piece that has hoses going into it that has the words "water" and "Fuel" written on it. Is this the VST?

If not, could someone please try to explain to me where the VST is on my motor and where the filter is and how to change it. I would appreciate any help you all can give me. Thanks.

 

[yamamarinetech40]

Re: VST Filter on '05 F115

No, that is not the VST(Vapor Seperating Tank), that is a fuel cooler...if you don't get the concept of what it is, it's probably not a good idea to get into it...but if you must-it's the aluminium(unpainted) TANK that's also on the port side but toward the front of the motor....you shouldn't need to change this filter for some time...you do need to replace the fuel/water seperating filter(10 micron!) in your boat on a REGULAR basis...don't empty it out and then reinstall it either, that contaminates the filter.
The filter inside the VST is very expensive and you have not one, or two, but THREE filters BEFORE this one...look up above the VST, hidden behind and above everything is an inline metal canister filter....you might pull and examine the contents of this one(empty it backwards into palm with taps)....

 

[rodbolt]

Re: VST Filter on '05 F115

the VST is located port side behind the intake manifold. manifold removal is mandatory for VST maintenance.
and it must be serviced occasionally.
the high pressure pump is a flow through design and debris from the motor brushes will affect the filter.
not that its much of a filter. a fuel pressure test guage is invaluable when servicing EFI motors. in fact its mandatory.