60L-13490-00-00 RELIEF VALVE ASSY testing

[fairdeal]

So this is one of the two devices which allow venting of the VST on the F225 txrd.
(the other is 69J-14989-00-00 ORIFICE, AIR VENT)

Testing with air, discharged through a bubble stone into water for visualizing flow.

This part is similar to the relief valve used with the lift pump, but it has a "white" (presumably polymeric) "ball"
and appears to "regulate" at ~2 psi.

Unlike the lift pump relief valve, which acts on fuel, this valve acts on "vapor".

So it is interesting that it is NOT "air tight" - some flow was visible under the slightest pressure, below that needed to deflect the gauge needle.

But it clearly "opened" by ~2 psi, and effectively prevented pressure from rising above that point.

Video of testing:

https://vid.me/48E9

Still shot of "ball":

[rodbolt17]

here again.
this aint rocket science.
that valve prevents MOST vapors from entering the air box.
at engine shut down if all the vapors entered the airbox the fuel mix would be to rich for a hot restart.
the EPA mandated part of that.
it is also why later versions vented into a charcoal canister and even later versions use a canister vapor valve.

all ya gotta do is think.
all the engineering work has been done.

[pstephens46]

here again.
this aint rocket science.
that valve prevents MOST vapors from entering the air box.
at engine shut down if all the vapors entered the airbox the fuel mix would be to rich for a hot restart.
the EPA mandated part of that.
it is also why later versions vented into a charcoal canister and even later versions use a canister vapor valve.

all ya gotta do is think.
all the engineering work has been done.

I think everyone understands the reason for this valve. The above exercise was to to determine if 2lbs pressure was the breakpoint.