Install additional fuel vent hose into existing line?

[JerseyBoater]

Hi,

Been having a problem with my fuel vent line, looks like quite a bit of fuel gets into it which makes filling up a slow process. It doesn't seem to affect engine performance as I guess it sucks it into the tank at that point and gets good vent flow.

The vent is currently part of the filler cap, so it runs almost vertically down about 3ft, but then goes horizontal about 4ft before a short drop towards the fuel tank. The boat is a Regal 2650 and seems a fairly standard way of doing it. The hose is also fairly well tucked in between the engine manifold and storage compartments.

What I think will solve my issue to add an additional vent line to a thru hull vent with a nice loop in it, and use a T connector right by the tank? I could even put a tap on this vent line so it's only open when I'm refuelling the boat rather than all the time?

Images attached of existing fill and vent line, and where I think a T connector could work.

Thanks

 

[mr 88]

Do not think you want a loop in a vent line. Seems to me your creating a possible fuel trap as in fuel gets to the bottom of loop and no air is getting by. I have never seen a boat with a loop in the airline A second vent line is not going to hurt anything. Nothing wrong with just Teeing it in without a shut off valve ,which wouldn't serve a purpose that I can see anyway.

 

[dingbat]

I would start by replacing the 21 year old fill hose and see where it leads you.

Have you blown air back thru the vent to confirm a blockage?

You would be amazed at how much stuff gets stuck/trapped in there over time

 

[Bondo]

Ayuh,...... There shouldn't need to add a 2nd vent hose, if it's properly designed in the 1st place,......

The vent hose should come off the "vent to outside" fittin', 'n loop Up, then loop down, falling all the way to the tank,......

The concept is,.... any water introduced into the vent will back up in the loop up, 'n then drain back out,..... not down into the tank,.....
'n so long as the loop down to the tank is continuously droppin', there'll be no resistance to the escapin' air when refillin',....

 

[JerseyBoater]

I removed the vent hose on the tank side, and trained a fair bit of gas out of it. Gas was in good condition with nothing floating in it. Blasted air through and confirmed nothing odd came out. Refilled perfectly after that for a few weeks then same problem again, gas in the vent line. At the moment the current vent hose goes straight to the filler and vent cap as it's a single unit type. (see attached photo)

I've also put an inspection camera down the filler and vent hose, no blocks and looked in ok condition although I was just looking for any delamination type issues.

 

[Bondo]

I removed the vent hose on the tank side, and trained a fair bit of gas out of it. Gas was in good condition with nothing floating in it. Blasted air through and confirmed nothing odd came out. Refilled perfectly after that for a few weeks then same problem again, gas in the vent line. At the moment the current vent hose goes straight to the filler and vent cap as it's a single unit type. (see attached photo)

I've also put an inspection camera down the filler and vent hose, no blocks and looked in ok condition although I was just looking for any delamination type issues.

Ayuh,..... You need to reroute the vent line, so it doesn't allow standin' gas in it,....

 

[ahicks]

Agreed. NO low points that might allow gas to pool in the vent line. You want to run the vent line so gas will either run toward the filler, or the tank.

 

[JerseyBoater]

Sounds like I'm going to have to bite the bullet and try and extract that vent line from it's current location and run it a bit higher up before dropping down to the tank. Thanks all

 

[dingbat]

Interesting setup.
Have never seen a situation where the fill and vent lines are on the same plane. Looks like topping off the tank would back flow into the vent line

Is this a new to you boat?

Did you or someone else change the elbow on the vent line?
They are normally a bit taller.

Gives you problems both in and out of the water?
I've seen this issue presents itself with the boat on the trailer but not in the water. Raising the trailer tongue resolved the issue

 

[Scott Danforth]

my guess is your vent line is too long and it has a dip in it. simply disconnect it from the fill assembly, and see how much extra line you have.

then trim as needed.

 

[JerseyBoater]

Had it 2 seasons now, 1st season didn't go very far so lots of short trips with small fuel ups. This season with longer trips been filling the tank before we set off which is when the problem became very noticeable. Boat is kept on a slip during the summer, out the water at the moment.

I rerouted the vent hose today, gives a much better rise straight off the tank before going horizontal and then up to the filler. I've just cable tied it whilst I go get some proper clips and in case I need to move it around but that should do the job.

Also found there is a spare valve on the tank itself, so if I did just run a new vent hose I wouldn't need to T into the existing one anyway! Hopefully this new route solves the problem but won't find out until next summer.

 

[Scott Danforth]

the ventline will collect fuel because you built in a P-trap.

shorten the run, it should be all uphill.