Fuel squirting out vent

Bob J. · Jul 9, 2016

Diesel foams when you fill a tank so the issue on a boat becomes too little relief from the vent system, too much pressure on the fill side so as the tank gets closer to being filled the vent burps taking the foam with it. Not much you can do about it except slow the fill process when the tank is close to full. Easier said than done.

seadaddler · Jul 9, 2016

I do get fuel come out the vent before where the hose full up is,no idea why and just go slow
and I can look under my bed to check if tank is full and fuel gauge is some what accurate.
Nick

Davidasailor26 · Jul 9, 2016

Fuel coming out the vent before the fill port is pretty common, although usually the vent is lower than the fill port. Just be glad that in your setup the spilled fuel is just on the deck instead of in the water. Filling at the minimum speed and stopping when the gurgling noise stops is pretty typical. You probably wouldn't want to fill the fill line with fuel anyway, as it will expand as it warms and could then spill out.

31seahorse · Jul 9, 2016

Just a trickle flow is difficult to achieve at some fuel pumps. Fortunately, our sailboats are not overly fuel thirsty. Whenever possible I put the fuel into a 5 gallon diesel jug and then dispense the fuel into the boat using a siphon of some sort. That slows the flow into the tank to a rate that the breather can deal with. Recently I have been using the type of siphon that has the orange squeeze bulb at the top, clear tubing, and a pressure relief twist cap to stop the flow. That prevents most fuel spill or overflow problems. Of course there are many other siphon gadgets on the market.

dlochner · Jul 9, 2016

Make sure there are no low spots in the vent hose. Fuel can collect in the low spots and then be forced out of the vent as the tank fills.

Place a fuel absorbent pad under the vent when fueling the tank. It will collect the fuel that spits out.

Look for a fuel dock that has a low pressure pump. Some docks that service large diesel power boats have pumps that will put out 40-50 gallons a minute. Hard to get just 10 gallons into the tank without spilling with one of these high pressure pumps. These pumps often have a larger diameter spout that does not fit into the typical sailboat fuel inlet.

Maine Sail · Jul 9, 2016

dlochner said:
Make sure there are no low spots in the vent hose. Fuel can collect in the low spots and then be forced out of the vent as the tank fills.

This is usually the #1 cause. Just like bilge pump discharge hoses there can be no dips, sags, low spots or even horizontal runs in a fuel vent hose. With the Installation of fuel fill & vent hoses it is critical to keep pitch and not create any "traps"...

All U Get · Jul 9, 2016

I added a whistle to the vent line which on our boat is higher than the deck fill. Any change in the sound and I stop fueling. My wife also gives the count-down on the fuel gauge, ours can be tuned to the full level. I also have a spill bottle which uses suction cups to hold the bottle over the vent in case some foam burps out (I don't think you can buy these anymore). We've traveled three times from Maine to Florida with only a handful of burps all caught with that bottle. Usually I stop at about 95% full, believe it or not you can find fuel about everywhere so we have one jerry-can for looks only.

All U Get

JamesG161 · Jul 9, 2016

Mark Maulden said:
I normally quit filling when i hear the deck fill noise starting to go up in gurgling sound... Here's the configuration:

I have a new fuel gauge (2 yrs old) that I calibrate each time I fill.

I keep rough log on fuel consumption to know ±gallon required to fill. I calibrated, my near empty 50 gal tank, with a slow 5 gallon , wait for gauge to stabilize, record gauge, 5 gallon more, Rinse and Repeat until ±95%.

Then verify my calibration and sensor each time I refuel and can rely on my gauge.

@Maine Sail is right on the only way to burp a vent, if you are filling it, very very slowly and pause for a minute after, say every 3 gallon, until you are close to your estimated fuel consumption.

All U Get said:
Usually I stop at about 95% full, believe it or not you can find fuel about everywhere so we have one jerry-can for looks only.

My calibration is good to ±5 gallons or I never fill the last 3 gallons, and thus my jerry can to us in a pinch.
I suggest you rotate the diesel in that jerry can, every 3 fills or so.

I am totally amazed that diesel fuel fill lines are not like cars, where the fill line and vent are combined with a back pressure cut off. I guess they would prefer the $10k fine versus stopping the spill.
Jim...

PS: IMHO your auxiliary power is top on your list of Safety devices, like PFD's.

All U Get · Jul 9, 2016

OK, took me a while, http://www.allpointsmarineco.com/view/8097/335788/
Hope the link works. This ought to be worth a beer.

All U Get

SFS · Jul 9, 2016

I like the idea, but it wouldn't work on my boat. The vent fitting doesn't stick out very far from the hull, and wouldn't put effluent anywhere near the mouth of the bottle, unless I've misjudged the scale.

All U Get · Jul 9, 2016

There's actually an opening on the back of the bottle with a foam gasket that snugs tight against the boat. I have the typical vent that sticks out about 3/4 " from the boat and it gets nearly every drop. You do need room around the vent for the bottle.

All U Get

Rich Stidger · Jul 9, 2016

I second the use of the No Spill bottle. I have used on for 18 years. A great device. Yes I sometimes get a spurt in the bottle just before the fuel rises in the fill tube. After removing the bottle, just pour the ounce or so back into the tank.

Maine Sail · Jul 9, 2016

The easiest way to solve the problem is a Racor LG100 Fuel/Air Separator.. I run one of these before my H2Out filter and they work tremendously well.

dlochner · Jul 9, 2016

Maine Sail said:
The easiest way to solve the problem is a Racor LG100 Fuel/Air Separator.. I run one of these before my H2Out filter and they work tremendously well.

Certainly, the Racor Separator is an elegant solution. However, 200 OIL ABSORB SHEETS PERFORATED 15 X 19 (EACH OR BALE) can be had for less money.

Stu Jackson · Jul 9, 2016

Gentlemen, I believe you may be unnecessarily complicating this issue.

Mark, IIRC your first post, your vent is ABOVE your deck fill. How one could even envision having the vent, well, uhm, vent fuel out when refueling, before the deck fill overflows, is something I do not comprehend, based on fluid mechanics and gravity. You say it did for you before, and I accept that on your word, but find it hard to believe.

My vent is a tad lower than my deck fill. If I am not very, very careful in filling, I will get a spurt out of the vent, and I stop immediately. As a few have mentioned, slow filling to avoid foaming is always helpful.

My recommened solution is to KISS

--- fill slowly

--- lower your vent, or forget using it for anything other than a tank vent which is there to avoid creating suction in your fuel tank as the fuel is used by the engine

--- don't use your vent as a "telltale" for fuel fills

--- use your engine fuel consumption instead of your fuel gauge and fill to what your consumption rates tell you (Once I started doing this 17 years ago, I have rarely had a spill; yeah, maybe I had a few ounces less than absolutely full, but, really, who cares?)

Good luck.

All U Get · Jul 10, 2016

If I could explain: When you're washing your deck and the water pools along the toe rail, do you use the force of the hose water to push the pool to a scupper or overboard? The same thing happens when you fill your tank. Pumping fuel down the 1 1/2 fill hose has some force and it makes pressure in the tank. With the air forced out the vent hose the only thing left is fuel that squirts out. Once you stop pumping the level of fuel in both hoses reaches equal levels.

(Filling a fire truck with a 4" hose does the same with water if you pump too fast. The result is water spouting out like a whale or the tank splitting along the seams. Sorry for this reference.)

All U Get

Fuel squirting out vent

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SBO Weather and Forecasting Forum Jim & John

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