Plastic Gas Tank Vents in the Lazarette

My gasoline tank is one of those red plastic 6-gallon Tempo gismos with a Nissan OB fuel line adapter. My motor began to act like it was sucking water. It coughed and died a few too many times at a critical time while running at 1/3 throttle after about two minutes at full throttle. After that, the motor would crank right up again, run for about 30 seconds to a minute, and then cough and die again. This happened at various throttle settings for about six cycles. Once I was back in the harbor, the motor ran perfectly. It was time for a service anyway, so I pulled the motor.

My mechanic agreed with me that the cause of my motor coughing and dying was likely water in my fuel. He recommended that I remove the “contaminated” fuel. When you heel an Ariel to 40 degrees and beat to windward there is one heck of a lot of water in the lazarette. On a port tack that water sloshes all around the gasoline tank. The Tempo tank has a funky little twist vent on top. I am not in the habit of closing that vent as long as the fuel line is connected to the motor. I always keep the vent closed when the boat is moored. I have not had previously had any problems with water in my fuel. Of course, I am not sure that I have that problem now either. If I do have water in the fuel, condensation could also be the cause rather than water entering through the vent.

I have now switched to the 3 gallon Nissan tank that came with my new Nissan 6 hp motor. It has what appears to be a more reliable twist type vent, which is located in the center of the filler cap/fuel gauge. I plan to shut the vent whenever I shut the motor down both when moored and also under sail.

Has any other Ariel or Commander owner had problems with water in the fuel and if so, have you devised a way to keep the water out, run a remote vent, etc.? Of course shutting the vent when not motoring would help, but these little twist type vents are only so good, and you have to remember to close them whenever the motor is not running...or do you?

I had that problem. I have some brackets glassed into the floor of the motor well to tie the tank down. However, I would often forget to open or close the vent. In the heat of the summer the plastic tank would expand and break the seals, and I wouldn't get good pressure in the tank.

Eventually I switched to a metal fuel tank. It has an "auto-vent". Always has good pressure. Dont need to prime the bulb. No more problems.

The metal tanks are expensive, but I found a new one on ebay that wasn't too bad. The tank will rust eventually, but I still like it better than the plastic ones.

A metal tank is an interesting idea. I have previously avoided metal due to the salt water intrusion in the lazarette locker. But perhaps I nned to go that way. I had a metal tank on my last boat. I kept it in a water tight locker, but it slowly rusted away even there. I wonder if a product might be available to effectively retard rust somewhat on metal tanks.

I am pretty sure that the valve on my 6 gallon Tempo tank was damaged due to heat expansion when my boat was high and dry in the yard for nearly a month this past summer. The valve no longer works as well as it originally did. If you tighten it more than slightly finger tight, it slips past slightly tight into open mode.

I was hoping that someone might have discovered a way to run an external vent from a plastic tank out of the locker completely to a vent on deck or the transom.

Building a form fitting but removable fiberglass tank is another interesting idea.