External Gas Filler Cap

Discussion in 'Wooden Boat Building and Restoration' started by Liam Conway, Jul 9, 2019.

  1. Liam Conway
    Joined: Jul 2019
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    Location: Pennsylvania

    Liam Conway New Member

    Hello, I have recently discovered boat building, please pardon any missed terminology. I have found a boat design by a company called Glen-L. (14' Zip - twin cockpit runabout-boatdesign https://www.boatdesigns.com/14-Zip-twin-cockpit-runabout/products/378/) While I like the boat overall, it feels incomplete. This boat is meant to be used with an outboard motor, I'm thinking if I do end up building it, I will use this, Yamaha 40 HP 4-Stroke F40LEHA Outboard Motor https://puarto.com/yamaha-40-hp-4-stroke-f40leha-outboard-motor.html?gclid=EAIaIQobChMItbGOvu2o4wIVB2SGCh0DYwc1EAQYAiABEgLY6_D_BwE. However, unlike boats that are built by companies, this lacks a gas cap, please excuse me if I use the term wrong, but it's the filler cap on the outside of the boat, where you would normally put the gas if you went to a (Boat) gas station. However, non of the videos online have answered my question. The gas tank is located at the bow underneath the front deck, you can see it from the cockpit. But I want the boat to feel more finished, so I would prefer to be able to gas up at a dock easier. My family and a few other close friends share a house at Lake George, NY. The camp's boat is a 2002 Chaparral 220 SSI. It's an inboard-outboard and has the kind of filler cap that i'm talking about. I'm sure you could find it on almost any boat. My second concern is the primer bulb. On our boat in NY, it doesn't have one, as it is an inboard-outboard. I am wondering if there is a way to automate it, or remove the need for it. With the gas tank being at the front. I would like the gas tank to be at the front, iv'e seen people talk about using gravity, but I don't want to risk anything. If both of these are possible, and you know how to do it, please let me know! Thank you.
     
  2. Ike
    Joined: Apr 2006
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    Ike Senior Member

    Is this a permanently installed tank or a portable tank? If it is a portable then the cap is on the tank itself. If it is a permanently installed tank then it should have a filler tube (actually hose) that goes up to the deck or gunwale and has a fill fitting on the top . The cap is built into the fill fitting. You can get them with a lock or without. See PERKO Inc. https://www.perko.com/catalog/non_epa_fill/fuel_system_components/ or Attwood Marine http://www.attwoodmarine.com/store/category/integrated-fuel/components-parts/deck-fills
    See here for diagrams of permanently installed fuel tank systems Boat Building Regulations | Boat Fuel System | Fuel Tank Diagram http://newboatbuilders.com/pages/fuel_tank.html When people talk about gravity feed they are referring to the tank being higher than the fuel inlet on the engine. The fuel then can gravity feed to the fuel pump on the engine so the engine does not have to primed. that's how it works on an inboard. Otherwise the fuel pump on the engine has to suck the fuel up hill to the engine. Actually this is not a problem on inboards. The fuel pumps on inboards do not normally need to be primed . They are self priming. But an outboard engine needs to be primed first, that's what the squeeze bulb is for. Portable tanks are usually near the engine and don't need long hose runs. The engine manufacturer supplies a hose, with a squeeze bulb, that simply plugs into the tank. With a permanently installed tank at the bow you need a long hose run back to the outboard. This should be USCG type A hose. But since it's an outboard you will need to transition near the stern, from USCG type A fuel hose to the Original Equipment Manufacturer (OEM) supplied hose with a squeeze bulb, to prime the engine. These setups are quite common and you can get all the parts needed from any marine retailer or online supplier. And no you should not eliminate the squeeze bulb. Just so you know, which modern fuel systems you may not have to do this very often. I have a small outboard on my 18 foot Sea Ray (an I/O) that I use for trolling. I prime it only at the beginning of the season. I've never had to do it again unless I unplug the hose. It holds the very slight pressure (about 1 psi) easily.
     
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  3. Liam Conway
    Joined: Jul 2019
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    Location: Pennsylvania

    Liam Conway New Member

    Thank you! All of this has helped greatly. I just wanted to confirm a few things, in the diagram, it shows the grade valve connecting to the vent hose. Is there a certain valve that allows 3-way connections? Additionally, is there a certain keyword I'm missing when I search "Vent with a Flame screen"? Thank you, you have helped greatly.
     
  4. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

  5. Liam Conway
    Joined: Jul 2019
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    Location: Pennsylvania

    Liam Conway New Member

    Thank you so much. You have been extremely helpful.
     
  6. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    Dont bother with an outside fuel vent out the side of the boat.
    Use a Perko VPR fuel cap and vented fuel fill.
    Example cap, they come in all sorts of metals and colors. The VPR is what you want.
    Buy it as a complete set, sealed cap with VPR and the vented fuel fill.
    PERKO Inc. - Catalog - Fuel System Components - EPA Compliant Sealed Replacement Cap with VPR [0660] https://www.perko.com/catalog/category/fuel_system_components/product/1104/
    I also used an Attwood fuel demand valve, that only allows fuel to be drawn out of a fuel tank when a fuel pump sucks fuel. Perko sells the same thing that screws into a tank, its a combination fuel demand valve and dip tube, but the attwood one is a lot less costly and goes inline with the fuel hose. So you dont have to mess around with your tanks fuel pickup tube.

    And I used a Perko anti well back one way valve that slides into the fuel fill hose. Prevents a fuel geyser out of the fuel fill if boat is rocking when filling up.

    This makes the system like your car, the Perko VPR is double vented, and lets air in or out of the tank after tank pressure exceeds 1 PSI difference to the atmosphere.

    the big advantage, it keeps your gasoline fresh, it also aids you in preventing fuel spills when fueling up.
    I no longer have to worry about water in the gas, or the gas going bad, I no longer use fuel preservatives.
    I notice usually the tank is under a very slight vacuum.
    It is very simple in concept.
     
  7. Barry
    Joined: Mar 2002
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    Barry Senior Member

    ABYC H 24.5.2 The entire system must be liquid and vapor tight to the interior spaces of the hull.
    So if the filler is a combination filler-vent, then this cap must not be inside the gunnel area, ie the interior spaces of the hull
    If your run is over 12 feet, you need a valve at the draw hose at the tank and one at the engine
    Any connections to the engine have to be outside the interior spaces of the hull, ie engine well
    ABYC 24.17.3 Overflow from the fuel tank vent at the rate of two gpm or less shall not enter the boat

    Summary
    If you have a vapor tight fuel fill cap, then it appears that it can be in an area that a kick back of fuel can enter the boat compartment ( I had understood that the deck fill had to be
    outside any engine/living/general interior compartment so that any blow back could not enter the boat hull)
    The vent cannot be over an area that any fuel leaving the vent can enter the hull
     
  8. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    I guess people are unfamiliar with the new Perko fuel fills or they would not say these things. Dont you think Perko knows what they are doing? They are EPA and ABYC compliant. The vent does not exist except in the cap itself, the vent hose is entirely sealed and turns back to the fuel fill. there is no vent over the side anymore.

    The large vent hose just vents the tank when refueling the tank as in rapidly filling it with fuel. Since the incoming fuel displaces air it has to come out and quickly.

    Then the cap screws down tight to the fill, the vent hose now does nothing at all.
    All the venting is provided by the valve in the cap, it is spring loaded and is normally sealed, If the pressure changes and exceeds 1 psi, it either vents out or is sucks air in.

    Thus it works like your car, except the car fuel cap is set to 2 psi, not 1 psi. they did that because the car tank is much smaller and the plastic car tank can take it. I am not bothering mention a charcoal canister cause on a boat retrofit who cares. And frankly I dont like keeping the vent open to the atmosphere and using a charcoal can on a boat to catch the vapors and having a 100 % sealed cap with no vent valve, I think that system sucks. See there are 2 approved ways, one is sealed cap no vpr valve, use charcoal cannister which vents to atmosphere=== sucks big time bad idea.
    The other is keep it 100 % sealed and let a sealed valve open and close but most of the time is not open to atmosphere === much much better, less humid air getting into ethanol gas, no charcoal canister needed. Gas stays much fresher
    You want to have as little as possible air exposure to gas, humid air gets into fuel, acetobactor grow, acids form, gas seriously degrades, maybe even phase separates.
     
    Last edited: Jul 29, 2019
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  9. Ike
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    Ike Senior Member

    I was the USCG liaison to the EPA on these new fuel systems back in 2001-2004 when they were developing the regulations. I tried telling the EPA that and got nowhere. Having a canister soaking up vapors is a safety hazard! Got nowhere. Having a pressurized fuel system is a safety hazard. Got nowhere. So now new boats are stuck with it. I have one of the new portable fuel tanks. In warm weather, like we are having right now, it blows up like a balloon. I have to unscrew the cap to relieve the pressure. Where the fuel line connects to the tank it is a simple press on fitting. I had to glue it in place to stop it from leaking when there is pressure in the tank.
     
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  10. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    yes, the small portable tanks no longer vent at all, they swell up.
    The big builtin tanks still vent through the double valved normally sealed fuel caps, a much better idea.
    I refurbished an old Quicksilver 5 gallon marine tank. It needed a new cap, I used one made for a I think Ford truck that is double valve vented, meaning it is normally sealed but lets in air as fuel comes out. And it vents out air if PSI rises. It works well the few times I have used it. It does not screw on, fuel cap is all steel and has 2 prongs. Another big advantage, if boat is bouncing, no fuel spills out, which can happen with a cap using a screw down vent valve.
    I mostly use it on a portable generator here at the house as extra fuel storage.
    I dont like highly pressurized gas cans like the new ones are.
    I have bought small yellow fuel can plastic vents and drill a 1/2 " hole and press them in, then the tank can be vented. And the gas comes out a lot better, no more splurting out all over everything making a mess, cause it cant flow out smoothly.
    Seems all the EPA cared about was a gas can sitting there to not leak out vapors and cared nothing for the usability factor.
     
  11. Ike
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    Ike Senior Member

    By the way, the EPA started out wanting a completely pressurized fuel system like in cars. They didn't have a clue as to what would happen if a leak developed. We finally beat them down to what is now the regs. I can only take a small part of the credit. Between us (my boss and I), ABYC, NMMA, the fuel tank manufacturers, and a few other organizations we finally got them to realize it would be a safety disaster. They had no one on their staff that knew squat about fuel systems on boats.
     

  12. sdowney717
    Joined: Nov 2010
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    sdowney717 Senior Member

    Interesting, well the right choice was made to lower the max PSI to 1 psi.
    I converted to the epa compliant Perko VPR caps a few years ago, and for practical reasons with today's gas with ethanol, it has made a huge difference in keeping the gas fresher.
    I have found the tank generally has zero pressure most of the time, you can tell when opening the cap no sound of air whooshing in or out, the other times it has developed a slight vacuum, I open the cap hear a whooshing noise, place hand or paper over opening and it has a slight vacuum.
    In fact it made no sound so often made me wonder if the valve in the VPR Fuel Cap worked at all, like just open venting the tank, that when I finally heard the whooshing noise I was happy, cause then I knew it was ok.

    Honestly you have a large lake of gas in a tank which takes a lot of temperature change over a long time to change the vapor pressure, so most of the time the cap is going to keep it sealed from the air, which has great benefits. I have thought the same idea for diesel would be good, since water in diesel is also bad.

    But you must use a fuel demand valve at the tank outlet with this type cap setup, and that has also worked well.
     
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