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2013 BF150 fuel filter/Vent hose question

R

R-W

New member
Hi everyone new to the forum..
I was changing fuel filters on my BF150 and ran into a suspicious line that I’m questioning. The inline filter behind the intake has a T in the fuel line above the filter that goes to a check valve (#16 in link below) then a short 90* hose that appears to be open ended (#8 in link below)
My question, is #8 short 90* hose supposed to be connected somewhere that I’m missing? Seems strange to be open ended but It’s a bit hard to see behind the intake manifold so I may have just missed something.


 
Hi R-W,
Welcome to the forum.

That 90°.elbow...item 8... doesn't have anything else attached. It is supposed to be open to atmosphere for venting of your VST.

Maybe you could help clear up a mystery your question has raised.for me though.
Could you tell me where the hose...item 4... attached to to the 3 way T fitting...item...15...goes?
The one that has F9 printed at the other end.

I think it may be a drain but I would like to know for sure.

Thank you.
 
Thanks for the reply. I assumed it was a vent but thought it should have some sort of cap on the end to keeps bugs or whatever out?

As far as #4… I will take a look, as I still have mine apart.

Edit: It goes to a drain out of the engine compartment
 
Last edited:
Ok, thanks. I appreciate it.

As an explanation for why I'm asking, I want to be able to explain the reason for that vent and to accuratly describe how it functions.
Problem is, I can't yet satifactorily explain it to myself so I'm doing some "homework" on the subject.

it would also be a great help if you might be able to look at the check valve..item 16 on yours and determine the direction it will allow flow. I can't find that info in the shop manuals I have.

Most check valves are marked to indicate flow either with an arrow or painted in a particular way but the pictures in the parts pages are no help and, again, I haven't found what I need in a manual. Google and AI don't explain the system well either in my opinion.

Sorry to ask you to work on your first day here but much appreciation for anything you can provide.
 
jgmo said:
Ok, thanks. I appreciate it.

As an explanation for why I'm asking, I want to be able to explain the reason for that vent and to accuratly describe how it functions.
Problem is, I can't yet satifactorily explain it to myself so I'm doing some "homework" on the subject.

it would also be a great help if you might be able to look at the check valve..item 16 on yours and determine the direction it will allow flow. I can't find that info in the shop manuals I have.

Most check valves are marked to indicate flow either with an arrow or painted in a particular way but the pictures in the parts pages are no help and, again, I haven't found what I need in a manual. Google and AI don't explain the system well either in my opinion.

Sorry to ask you to work on your first day here but much appreciation for anything you can provide.
Click to expand...
No problem, I tried to upload a pic of the line you asked about but it said “It was just to much” or something along those lines…
As for the check valve it has an arrow pointing toward the T labeled “VLV open”
I’m assuming this allows air into the line? That’s how it appears to work..
This engine I’m working on has 189 hrs and had 132 when I bought the boat.. I don’t think it’s been tampered with much, Runs great just doing maintenance.
 
Yes, uploading pics here isn't always easy. I find that I have to resize down to 40 and sometimes.even 20% to get them to go. It's a good thing the cameras on most phones these days are so good.

Not surprised that the check valve is labeled so cryptically. As in "clear as mud". Oh well, I guess I'll assume that flow does happen in the direction of the arrow. Which, by the way, is opposite to what I find in AI.

AI states that the fumes from the float tank during filling are vented to atmosphere after being "scrubbed" by the filter.

With flow entering the T in the opposite direction and traveling toward the VST, that would make the system act as a vacuum break.

But with hose 4 attached to the T, it would need one heck of a restriction or even blockage for that to make any sense.

Thanks for trying. I guess I need to keep investigating.
 
I’m wondering if the check valve allows air into system, to break the vacuum… allowing fuel to drain out of hose #4 outside engine compartment where it won’t be a fire hazard…
I believe this would only become a concern if the filter I replaced becomes restricted?
The check valve positioned in the direction it is, would keep fuel from being able to reach engine compartment?
I also see the direction of flow on the filter is going into the VST so I am thinking it’s a return line from the fuel rail..
 
I can agree with most of what you propose but if hose 4 is simply open to atmosphere, then I can't see the purpose of hose 8 or even a check valve and T fitting.

Air flow or vapor flow would simply occur through hose 4 as it has to requure at least a small amount of force to open a check valve making hose 4 the path of least resistance.

I'm missing something fundamental here and hope I can eventually locate "description of opeeation" buried somewhere in one of the manuals.

I did find a discussion about the VST vent for an OMC outboard where a T fitting and a hose similar to hose 4 was used. But the engineers were using that hose to direct the vented fuel vapors to the intake manifold so the engine could burn them. A form of evaporative emission control.
But the "#4 hose" in that system was described as having a brass tube with a "carburetor jet type tiny orifice" molded inside and hidden in the rubber hose.

The problem there was that those guys were trying to figure out exactly how that system worked and were confused themselves. So, I'm not convinced their info was entirely accurate.

Oh well, I'm gonna sleep on it and try again tomorrow.

Cheers and good night!
 
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