I recently purchased a small portable marine fuel tank. When I got home, I realized that the cap was not vented. I contacted the manufacture and was told that due to Federal Government mandate, that the caps would no longer be vented. Also was told to vent the tank by loosening cap after pressure has built up. Well I did and there is a lot of pressure built up after one week and quite a bit of tank expansion. It just doesnt seem safe to me. Got a good spray of gas when I popped off the cap.
Is this the Federal Governments attempt to address the problem of ethanol in the marine industry? To mandate the marine fuel tank companies and leave the millions of boaters with existing vented tanks to deal with the issue themselves.
Why not produce a marine use only ethanol free fuel for the rest of us.
Now because I don’t know, why can’t marine fuel systems be sealed? If the tank and fuel lines were steel (to prevent expansion) couldn’t the system be closed resolving the issue of moisture in my fuel tank?
Because even steel expands under pressure, and I’m sure that’s why they need to be vented. When liquids get hot and cold they expand and contract, so lets think about what that’s doing to the welds… I agree with the initial poster, no vent seems a bit rediculous, but this may be because it’s a portable tank, most 5 gallon gas cans come with lids which are vented or at least prevent overpressure…
“The Wet Dream”
20’ Pioneer 197
150hp Suzuki 4-Stroke
you can’t seal a fuel system, air has got to replace the gas as it is used if not a vacuum will form and the engine would starve for gas. Cars are “sealed” but they have an EVAP system that burns the vapors and allows air back into the tank. My boat has a so called sealed system, air is allowed in as fuel is burned, the vapors have a pressure release valve so excess psi is released to prevent damage. I had the bright idea when I make my jon boat tank…I put a fuel cut off valve on the vent line to “save” gas as it sits.I can out one hot summer day and my rectangular 16 gal. gas tank looked like a 20 gal bean bag chair. Welds held though…
To me the mandates, even if they are only on the plastic portable tanks, are an admission from the Federal Government that they are aware of the problem that boaters are having with Ethanol fuel. Also the expansion on the plastic tanks seems very dangerous if you forget to loosen the cap.
I guess you could always leave it loose but it clearly states on the cap to turn until three clicks which is very tight. At first, I didnt think the engine would run without the flow of air to replace the spent gas but it hasnt sounded like it was starving for gas the past six trips of over 20 miles each @ WOT half the time. Also, at the end of the day the tank is still expanded. I would have thought with no air flow, the tank would have been caved in with the vacuum
You could use a bladder system to contain the fuel and enclose it in a steel tank to allow for expansion and contraction. That would keep any moisture away from the fuel. It would also cost a lot to buy a fuel tank.
