fuel tank vents ?

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5 years 2 months ago #2121 by David Irwin
fuel tank vents ? was created by David Irwin
I have a problem with filling the starboard side fuel tank. With anything more than a trickle the fuel blows back up the pipe onto the deck to be soaked up by "diesel diapers". I was wondering if I was missing some conventional wisdom about not putting vents lines to these port and starboard tanks. WaS it a common oversite on Whitbys that none of my previous owners ever got around to?
thanks in advance for any and all information

Regards
David Irwin
S/V Comfort #121
The following user(s) said Thank You: Robert Snelling

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5 years 2 months ago #2122 by C. William Eilers, Jr
Replied by C. William Eilers, Jr on topic fuel tank vents ?
I had the same problem and determined that the tanks were vented but the vent line was getting filled when the boat heeled. On my brewer 12.8 the vent hoses pass through the aft end of the starboard locker in the aft cabin. I inserted a 3 way valve in the vent hose with a 2 foot piece if hose on the third leg. Before I fuel up, I open the tank filler and through the valve so that I can blow through the vent line to the tank and clear it of trapped fuel. This also stops fuel from spitting out the vent line when filling the tank. As soon as the line is blown clear of course you have to through the valve back to vent the tank to overboard.

Would have been a better solution to try to reroute the vent line so that the fuel would drain back by gravity but much more difficult.

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5 years 2 months ago #2123 by Frank Fitzpatrick
Replied by Frank Fitzpatrick on topic fuel tank vents ?
Just Desserts (ex Menehune) has only the stbd and center tanks, but has vents on both and both work OK (for details about "ok", read on -).

John Cece (the P.O.) made several changes in the tank vents. They originally exited through the transom (much too low, to my thinking), and John rerouted them to exit through the after ends of the cockpit coaming boxes (much better). John also installed Racor "Lifeguard" fuel/air separators in each vent line. As a result of John's efforts, we have never had fuel exit the vent lines. So the combination of better routing and the Lifeguard gizmos are apparently doing their job.

The vent lines are nicely run (continuously upward, with no low spots to trap fuel). But I suspect the Lifeguard gizmos create a bit of resistance in the vent line because filling can sometimes be a bit slow and there has been the rare "diesel belch" back through the fill pipe if I fill too rapidly. (I've learned to listen for some advance warning in the form of a change in the "gurgling" sound if I'm filling too rapidly.) (Also, there is a small valve on top of each tank that can be opened to insert a dipstick, and if I open this valve while filling, air would much rather vent through the valve than through the vent line.)

I'm not entirely certain the fuel/air separators are necessary, and John would be the best person to address the following and his reasons for installing the fuel/air separators -
- Both vents now exit through the after end of the cockpit coaming boxes. This is probably about 8" - 12" higher than the fill plates, so I wouldn't expect fuel would come out the vent line if the tank were filled beyond "full". And they are certainly enough above the top of the tanks that fuel would probably never come out of the vent line due to heeling. Perhaps the fuel/air separator's job is to trap any fuel "spray" being carried up the vent lines with the venting air? I don't know.

John gave a presentation on the new vent system during the 2014 Whitby Rendezvous at West River. Unfortunately I wasn't able to attend, so I don't have his information to offer here. I'm sure John is reading this and perhaps he can let us know his experience with the issue.

Hope this helps,
Frank
Just Desserts (#195)

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5 years 2 months ago #2125 by Robert Strickland
Replied by Robert Strickland on topic fuel tank vents ?
We also added a larger vent hose(5/8") to all tanks and routed them up behind the cockpit combing. Tha t really helped a lot.
The starboard tank fill makes a sharp right angle turm as it enters the tank, which can also contribute to the back up, but putting the larger vent lines in made it much improved. I have found that if I start the flow slowly and then gradually increase it, I can run the fill at full blast.
Dee
Allegria 199

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5 years 2 months ago #2126 by Edward Schwiebert
Replied by Edward Schwiebert on topic fuel tank vents ?
If the tanks have been filled in the past without incident (and that has to have been the case given the vessel's vintage), I would suspect a recent change in circumstances. On our B44, we had bugs build very intricate nests of leaves that prevented the vents from performing. We cleaned that out, installed new screening, and all has been fine since.

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5 years 2 months ago #2127 by John Cece
Replied by John Cece on topic fuel tank vents ?
My friend, Frank, knows me better than I thought !

The fuel tank vents were changed after I had overfilled the starboard tank, and subsequently spilled fuel out of the vent (located at the transom).

The now shorter, vertical vents have worked very well. If overfilling the tank, fuel will escape at the fuel-fill, first.... should never escape from the vent, which is approx. 6" above the fuel-fill.

The Racor fuel-air separator(s) located in the vent lines were not needed, but installed as extra precaution so as to NOT ever spill fuel again !

John Cece
ex-owner MENEHUNE (#195); now: JUST DESSERTS

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5 years 2 months ago #2128 by Frederick Chance
Replied by Frederick Chance on topic fuel tank vents ?
Check to see if your vent fitting as it exits the boat is blocked by a mud dobber nest Mine has been a couple of times Once cleared it works fine again

Brewer 44 Hull #281 Wild Oats Fred Chance

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5 years 2 months ago #2129 by David Irwin
Replied by David Irwin on topic fuel tank vents ?
Thanks you for all the replies, I am blown away.
There is no vent visible on the outside of this boat except the at the stern which I figured was the center fuel tank.
Sounds like the best route for this boat is up into the cockpit coming cuby and out over the fill point.

Thanks again for your efforts

Regards
David Irwin
S/V Comfort hull 122

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5 years 2 months ago #2130 by Frank Fitzpatrick
Replied by Frank Fitzpatrick on topic fuel tank vents ?
Be careful what vent you disconnect. On Just Desserts (ex Menehune) there are two vent fittings going through the transom. One apparently was for the fuel system (currently disconnected and capped on the inside - see previous posts), however the second is the vent for the holding tank.

Judging by what I see now - and I don't know if this is the normal Whitby setup - the fuel tank vent line was copper tubing and went to the port transom vent fitting, whereas the holding tank vent line is rubber hose and goes to the stbd. transom vent fitting. (It appears that the center and stbd fuel tank vent lines joined together at the one transom vent fitting. Just Desserts doesn't have a port tank, so no idea whether the port tank vent normally went to the same fitting or had its own somewhere else.)

[P.S. - if your holding tank vent is not through the transom, please let me know where it is and how well it works. I don't think the transom is the best place for ours - long run and NOT continuously upward - but I don't know where else would be better.]

Hope this helps
Frank

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5 years 2 months ago #2131 by Mark Popiel
Replied by Mark Popiel on topic fuel tank vents ?
Hi

I had the same issue. The reason was that my centre tank was over full and fuel blocked the vent line. On #153 the stbd vent lines goes down to the centre tank, and they vent together.


The solution is to move some fuel from the centre tank until the vent line is no longer blocked


hope it works for you.
mp

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5 years 2 months ago #2132 by Jack Dexter
Replied by Jack Dexter on topic fuel tank vents ?
I had this problem with the fill belching back fuel. I even had it worked on by a professional who re-routed the vent line which helped but did not eliminate the problem. I then discovered that if I used a large funnel (not Baha) and ran the fuel into the funnel the problem went away. I use the largest funnel with the largest hole in the pointy end that will fit in the fill pipe. I can get fuel in more quickly this way, too. If I'm fueling too quickly the fuel simply backs up in the funnel and doesn't go all over the deck.

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5 years 2 months ago #2133 by Dale Kramer
Replied by Dale Kramer on topic fuel tank vents ?
All our fuel vents were re-run to the outside of the winch deck years ago. This gives the vents an almost straight run to the tank.

We have had no problems filling at a full rate.

Dale Kramer
S/V Puffin #169

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