Rodbolt, why is this used

[boscoe99]

on some models only. It is a $40 fuel filter that is in the vent line from the charcoal canister to the over board vent. Installed on the F150 and F200/F225 but not the SHO or Offshore models.

Why would a vent line need a filter?

[rodbolt17]

why is it 40n bucks, cause they can get it.

its used to filter air.
why is it not used on various other 4 strokes, dunno.

maybe someones bro in law makes filters.

[Nautical]

Why are any of those U or F shaped filters 40 bucks? and why do they have to be U shaped ?? I suppose fitment is the answer , but a straight one 10 micron probably 10 bucks. ???

[boscoe99]

Why are any of those U or F shaped filters 40 bucks? and why do they have to be U shaped ?? I suppose fitment is the answer , but a straight one 10 micron probably 10 bucks. ???

$40 plus because it is from Yamaha.

Why they are U shaped is so that they can contribute to a restriction to fuel flow in a fuel system. Yamaha uses hoses with a small ID, uses many fittings and hoses, filters that make 180 turns, and then cautions people to be wary of an overall restriction to fuel flow. DUH!

I guess the use of the vent filter comes from my thinking about Yamaha's thinking, which is if three parts are needed to do a job then we will use 6.

I dream of the day when there is just one hose from the fuel tank going through one inline filter on the motor. From the filter the hose go directly to the pressure regulator which is attached to the EFI rail. Smooth and unrestricted flow for the gasoline.

[Nautical]

LOL..you are sooo right.One uncomplicated fuel system would be nirvana..

[rodbolt17]

air has to flow both ways into and out of the VST. that's why they filter it.
the vapor shut off valve#15 controls air out of the VST at shut down, EPA says no venting of vapors to the atmosphere.
at engine start there is a delay then the ecu starts opening the shutoff valve to allow vapors in the charcoal canister to enter the air box to be burned.

cars been doing it for 30 years or so,back when cars had charcoal canisters and carbs anyway.

[boscoe99]

air has to flow both ways into and out of the VST. that's why they filter it.
the vapor shut off valve#15 controls air out of the VST at shut down, EPA says no venting of vapors to the atmosphere.
at engine start there is a delay then the ecu starts opening the shutoff valve to allow vapors in the charcoal canister to enter the air box to be burned.

cars been doing it for 30 years or so,back when cars had charcoal canisters and carbs anyway.

The air being filtered is to the charcoal canister, not the VST. In some models only. Later models don't have any filter at all to the canister.

[rodbolt17]

if you follow it far enough #9 in the last diagram is the VST vent to canister.
that line is the ONLY way air/vapors may enter OR exit the VST .
the early F200/F225 used a oneway check valve setup.
similar to the valve on the lift pump bypass.

sometime about 2008 or so the EPA said no more venting vapors to the atmosphere.
at engine shutdown the vapors are routed to the charcoal canister where they are trapped.
at the next engine start,based on a few sensor inputs, the ECU can toggle or completely open the vapor shut off valve allowing intake air to draw the previously trapped vapors back into the intake,IF additional air is needed in the VST it is drawn through the overboard vent line,typically on one of the rear cowl latches,,through the canister, filter and finely back into the VST.
why some have filters and others don't? your guess is as good as mine yet about all EFI 4 strokes since about 2010 have the VST vapor shut off valve.
the canister allows air one way,if we vented the VST directly to the intake,remember cant vent it to the atmosphere,then excessive fuel vapors can and will cause a hot restart problem that was erroneously called vapor lock.

all the EFI 4 stroke VST venting is done about the same since about 2010, why some use a filter and some don't is way beyond my pay grade.
I just gotta figgure out how to make them run correctly.



wait till you get the first one that dubbers got in the vent line at the cowl release.