So with the new outboard I decided to buy a new gas tank rather than use the small one that came with the motor. I bought it at West Marine. It does not have a vent because they say that having enough room after tank is full leaves room for expansion and helps fend off moisture by not having a vent. Well with less than 3 gallons of gas in the 6 gallon tank we were at the boat this morning then leaving for a few hours we returned to a smell of gas when getting back to the boat. Looking in the locker I saw that gas was leaking from where the gauge is and where the feeder spout enters.This is the second time this has happened. The pressure causing the tank to expand is forcing gas to leak from wherever it can. Do you think it is just because it has no way to vent (west marines tech) or because it is a faulty tank? Going to return it tomorrow but do you think I should try another West tank or not?
Same thing happened to me. A WM 3 gallon tank as well. Yesterday I went to the boat and was tinkering with the rigging and kept smelling fuel but didn't think much of it. I went to give the motor a start just to give her a workout and low and behold there was about 1.5 gallons sloshing around the lazarette.
Agree with blutoyz.
As the pressure increases the gasoline will leak from 'any' possible 'weakness' in the tank .... including the fuel connection hose 'joints' and hose barbs, etc.
Indeed most of these 'CARB' compliant systems are entirely bogus and ultimately quite dangerous; but, its now the 'law' in most places so you cant really do anything about it ---- other than CONTINUALLY/OFTEN tighten down and reseal (ad nauseum) until all potential leakage areas in the polyethylene tank are sooooo deformed from the constant tightening-down that you will soon/often need to replace the tank, etc.
For new gas tanks, with some exceptions for smaller producers, either no vent or vent filter. Given the high vapor pressure of e-10, no-vent has proven unsafe in the opinion of most boaters.
There is no way an unvented tank makes sense in any sort of below deck compartment, and in my opinion, given the leak history, on any boat with enclosed cabin spaces. If the boat is more than a skiff, open the vent or instal a proper tank in a proper tank compartment. The US Coast Guard does not permit pressurized fuel systems or components on gasoline applications, so I believe these tanks violate USCG and rules if you have a cabin and probably do bad things for your insurance. This is one reason the vent filter systems and caps were NOT pressurized under the new EPA evaporative emissions program; the USCG forbid it.
And while you're at it, install a vent filter. They are one of the few EPA ideas that does work, particularly on boats, though the EPA design is wrong (silica gel or silica gel/carbon hibreds are better).
FWIW we had a similar problem with an earlier, somewhat different model, WM gas tank. With the first and with a subsequent exchange/replacement. Rather than go for a 3rd exchange/replacement I examined the tank carefully and discovered the leak was through the gasket on the level indicator (in our case). With that, I removed the thing and made up a replacement gasket of cork gasket material from Discount Auto. With that, and a small bead of silicon between the gasket and the tank (but not the level indicator), our leakage problem was solved. If you open and vent the tank somewhat after the hottest part of the day, the pressure doesn't seem to build up enough to cause leakage, at least on ours. FWIW you can also make a vent in the fill cap with a small nylon fitting made for venting air from pool filter canisters or home-made with a nylon fastener from Home Depot.
WM usually sells Moeller fuel tanks and they are really junk. We have not had any product made by Moeller, especially their fuel tanks, last more than a few months. we purchased tanks with the Nissan brand name on them, don't know who makes them, and they have lasted for the past year sitting on the deck of the boat and getting heavy use and no issues with leaks even when they blow up like a balloon sitting in the sun. Occasionally we open the vent to release pressure. We did a blog post on our Moeller experiences, The Trawler Beach House: Moeller Marine Products Review . Prior to the complete failure of the gas tanks, they leaked like crazy. Chuck