Diesel Fuel Overflow line

[Alika]

My previous boat, an Ericson, had a vent outlet on the transom more than an arms length from the filler pipe. I bought a drip catcher designed for that purpose sold at the fuel dock. It was to be held in place with suction cups that never worked. I put two snap fasteners with an elastic strap to hold the drip catcher bottle in place. Worked great and allowed me to refuel safely without a crew member.

[Terra Nova]

Originally Posted by JOHNMARDALL

...The suggestion to blow the vent line out with compressed air, toward the tank, with the fill cap off, is a good one...

Sorry but this is not a good idea.

Don't apply any more pressure than just blowing your breath into the line . That will tell you if there is an obstruction. If there is an obstruction, you probably don't want it inside your tank, either. So remove and clean or replace vent hose.

[Bill Seal]

I guess too much time at sea affects reading comprehension.

When we started fueling, almost immediately the diesel OVERFLOW LINE high on the transom started leaking diesel

He said the VENT line started puking fuel. Everybody then came onboard stating it was plugged vent. He did NOT say the fuel was coming out of the fill pipe, but rather the VENT.
BTW, the idea of a water/fuel catcher in the vent line is a good idea, I'll put that on my to do list.

[Cheechako]

It's very common to have that happen when filling. However you say it didn't before? That seems strange. My theory is that any horizontal run in the vent line causes it. Fuel sits in the line low spot, when you fill, the air pressure burps that fuel to the outside vent constantly. Check your vent line runs and see if there is any way to make the horizontal section run only up hill to the vent, even if just slightly so.

[artisanmach]

I have a Vetus splash stop installed and vent is in cockpit. It totally solved my slow fill problems... I would recommend it to anyone...

[boatbod]

Look folks this is really quite simple. If fuel is trapped in a low spot in the vent hose, when you start filling the tank the increasing air pressure inside the tank eventually expels some or all of the trapped fuel out the vent. The velocity with which it is expelled directly related to how fast you try to fill.

Vent lines need a continual downward slope so they don't trap fuel and quit working.

[roygee]

Originally Posted by Alika

I installed a trap for diesel bubbles right at the vent line exit from the boat. It is a re-purposed water line filter. It has a drain plug at the bottom, the cylinder is clear so it is easy to look in the lazarette and view any diesel that needs to be drained off. Also plan to fit it with a desiccant in the airway to prevent moist air entering the vent line. I should patent it.
The action of the boat with a diesel tank near full will cause diesel fuel to bubble up in the vent line and even the most vertical vent hose is not always so vertical when the boat heels.

Practical Sailor has already talked about this it is called H2O gas vent filter, very good for gasoline tanks with ethanol in the fuel. Concerning the desiccant for moisture infiltration.