External Fuel Tanks for Gas Outboards on Hobie Islands

Greetings,

I know there are a couple people who have added external fuel tanks to their Hobie Tandem Islands. I was curious how people chose their external tanks (maximum size, placement in the boat). I would love to add a 6 gallon with 5/16" adapter, but cannot find one that fits in the hull of the boat. A lot of the ones I see on Amazon have reviews saying they swelled in size under the sun without proper ventilation because of new EPA regulations for the gas cap and leaked all over the place. Has this happened to those who have external tanks or how was this issue tackled (e.g., install old venting caps and then risk losing fuel volatility, fuel demand valve)?

Thanks!
Frondwonderland

Hello FW!
Have you considered making a mount out on the akas for the external tank? This is what I am planning to do. I only have a 3 gallon tank and that seems to be plenty. If my calculations are correct 3 gallons will give me a range of about 150-200km depending on speed etc! Its a regular boat tank with a std venting cap. I have had no spills or leakage so far but I try to close the vent valve when the motor is off and try to remember to vent of some pressure now and then if its a hot day.
The extra weight of the fuel dont seem to be a big issue anyway with the 3 gallon tank werever I place it, front or rear. I figure a smaller tank and an extra "jerry-can" if you are going for a really long trip might be a better more practical sollution? You can spread the weight better on the kayak and its also easier to carry.
Just a few thoghts... hope it helps...

All the best!
/Gustav

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Sailing my TI and fishing.... thats bliss!!

In general, an external tank will not work with smaller outboards (3.5HP and under).

I guess some outboards can be converted to use an external tank if you add a valve and T-connector but it all depends on the fuel line setup inside the motor and a little on the type of carburettor used in the specific engine.
It can be pretty messy to fill up the internal tank out on the water so I just love having the full range in the external tank. Never even filled up the internal tank on my 5hp so far, but I will use it as a safety backup in the future.

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Sailing my TI and fishing.... thats bliss!!

For my 3.5hp two-stroke, I rely on the 1.5 litre built-in tank, plus I bought a couple of 1 litre aluminium bottles, which I store on deck. If going away for a really long time, I would add a 5 litre plastic container, but I hardly think this will be necessary. After all, my TI is a sailboat!

Tipping fuel from the 1 Litre bottle into a small funnel is easy...

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Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker

FWIW I modded a 1 gal plastic can per Walt's idea to fill my Honda 2.3. Also carried an additional 1.75 in a Rotopax on my recent frolic. The auto-stop works like a charm - not a drop spilled - but I did shelter in coves to avoid mishaps while refilling. Having a larger tank connected to the Honda 2.3 would be nice but I'm not sure that it's possible....

Thanks everyone for responding. I have a T splitter on my Suzuki 2.5 HP so that I can use the internal tank and an external tank. Unfortunately my planned trips are 75 nautical miles (86 miles) each way, so an external tank is the solution I will choose as I do not want to refill and restart my motor every 8-9 miles. I am mainly looking for solutions to carrying 6 gallons or more and not having a gas leak so that I have to call my unlimited Gold towing service.

Assuming you have one of the small outboards that only have the small internal tank (ignore this if your outboard already is set up for an external tank) woops.. I see in your last post you have the Suzuki 2.5..

Some friends with small sailboats using the tank motors have a setup that might work??

This setup uses a standard outboard external gas tank - fuel line - bulb pump - fuel line - open/ close valve - fuel line that gets put into the outboard tank during refils.

The bulb pump has a one way valve on either end so it will pump gas from the external tank to the outboard tank. When pumping gas, you open the valve in the fuel line. When done you close the valve otherwise the tube could siphon gas out of external tank. Closing that valve can be very important if you lay the end of the fuel fill line lower than the gas tank.. it will siphon all the gas out of the tank as the bulb one way valves would allow this.

Im not sure how they tell when the outboard tank is full. A refil on the water might involve removing the outboard gas cap, putting the hose into the tank - opening the valve in the gas line and pumping the bulb until you see the gas near the top of the tank.

Man.. didnt read your post.. Is that T splitter after the outboard fuel shut off valve and before what looks like its probably a fuel pump - sort of situated above the cylinder head?

Slick if that can be hooked up to an external tank with a pump bulb..

Yes Walt, this is what the mechanic at my local Suzuki shop recommended for installation of the T-splitter. I am hopeful it works correctly.Thank you for your suggestions from your sailing friends. This is very helpful! It seems the external fuel tank is going to have to be stored on the trampolines based on everyone's input.

Thanks everyone!
Frondwonderland

Wow!l That sounds like an adventure. Where are you going??