VST relief valve assembly

[fairdeal]

Yes, we are all off in the weeds.
Rodbolt, then I, jumped to the conclusion that it was a F200/225/250 part:
69J-24460-00-00 (RELIEF VALVE ASSY)

Which regulates the pressure supplied to the VST by the electric lift pump.

But as later pointed out, the OP has an F150txrd. Which has a mechanical lift pump.

But it does have a similar device on the VST vent :
63P-24460-00-00 RELIEF VALVE ASSY

The purpose of which is to allow excess fuel vapors to leave the VST and go to the airbox.

Some models of F200/225 also have such a valve, for the same function, although a different part number:
60L-13490-00-00 RELIEF VALVE ASSY

Here is my F225txrd with both nearly side by side:



As Rodbolt has stated, the lift pump relief "goes off" at about 10 psi.
I have posted some early material from the F250 which (to me) seems to state 11 psi.

I once played with the other (VST vent) valve from my F225, but my gauge was not sensitive enough to get a good value for when it "opens".

IIRC somewhere near, or less than, 2 psi.

[pstephens46]

Just got back from boating and I fear I will need an umbrella....yes F150 TXRD. The barracuda man has it correct. Valve in between VST and intake. I did use the term from diagram...other than that not enough detail. I ask due to the "hot starting," issues posted many times before. Price is still shocking...

[fairdeal]

Yamaha made a few tweaks to the VST venting through the early years of the F200/225.

Some engines had problems with "hot restart" -
they became "flooded" after being shut down hot, due to excessive fuel vapor from the VST collecting in the intake silencer.

Yours was the first iteration, with only "69J-13490-00-00 RELIEF VALVE ASSY"

Which - from your picture/description - is not a "valve" but rather a kind of "orifice" -

similar to "69J-14989-00-00 ORIFICE " which replaced 69J-13490-00-00 for the 2003 model, and continued in that position until 2008.


They both apparently are a "restrictor" - allow air/fuel vapor to vent from the VST - but only as a con*****ed rate.


I posted my "testing" of the "69J-14989-00-00 ORIFICE "

since I was set up to test the relief valves, I went ahead and did the same with the "orifice" which allows vapor to vent from the VST to the intake silencer.

As the name implies, there is no moving part.
Exactly what is inside is not apparent; the view at either end resembles, to me, a cigarette filter.




As expected, very different behavior from the valves. Flow seemed fairly constant regardless of the pressure applied, and there was no "relief" - I easily maxed out the gauge.

Here is video of the testing:

https://vid.me/hIOa

If your "69J-13490-00-00 RELIEF VALVE ASSY" became "plugged" - it would cause the VST to no longer be vented.


Without a vent, if you drained the VST, you would be unable to fill it with the primer -

but once fuel is in the VST, I'm not able to imagine that lack of venting would cause a problem at idle.



You can certainly just remove your "69J-13490-00-00 RELIEF VALVE ASSY" and run without it, to see what difference it makes.

Just be aware that there will be some fuel vapors escaping the hose that it is plugged into

[seahorse5]

Would the inner "foam like" substance be to protect the VST from an intake manifold backfire flame? Some outboard companies in the past used steel mesh or a slightly open reed valve to accomplish the same thing.

[fairdeal]

flashback arrestor
makes sense

[99yam40]

I am sure you also would not want a good solid stream of liquid fuel to be heading to the intake manifold if the needle and seat stuck open for some reason in the VST.
restricts both ways

If it is not in the same line it will not prevent flames from backing up it