I just found an OMC 6 gal tank for Evinrude/Johnson at a local dealer that has the OMC fitting on it, a gauge, and the cap has a rubber ‘duckbill’ on the underside which he tells me will let air into the tank, but not out of the tank. So I’m going to see how it goes.
I have one of those OMC 6 gallon plastic tanks that I got used 25 years ago; and, it works great, and the minor swelling has not been a problem…..or it did work great until the rectangular black assembly that contains the gauge and fuel line connector developed a hairline crack and leaked when the tank was nearly full. The material looks just like the cast aluminum part on the metal tanks, but it is plastic. The crack was so hard to see, that I thought for a while it was seals on the connector leaking. I took that part off a metal tank and it fit the plastic tank perfectly, except have to play around bending the gauge float wire to get the gauge reading properly due to differences in the geometry of the tank. I like that tank and would buy another if one showed up near me at the right price.
For aftermarket 6 gallon plastic tanks with the gauge and a vent screw in the filler cap, there were a zillion of those sold, and Yamaha also used them in the early 2000’s with their name private labeled on the tank (my 2004 25 HP Yamaha on my pontoon came new with one). I was given two other tanks like that over the years, but the lens in the cap for the gauge eventually goes bad and comes loose or cracks, producing a bad fuel leak as gas sloshes around in the tank. The manufacturer is out of business due to lawsuits from fires resulting from these leaks, and for that reason, you can’t find replacement caps that have the proper fit and depth of the gauge float for these. I found a Briggs and Stratton replacement garden tractor cap that screwed onto these tanks with a couple pin-hole vents that are open all the time, but when the tanks were near full , they leaked gas out the vent as you bounced around hitting waves and/or cornering. I threw those two tanks away because I couldn’t find suitable caps. Maybe somebody now makes a cap with a vent screw that will fit and not leak?? otherwise, I will throw out my Yamaha tank when the non-replaceable gauge/lens/cap breaks or comes loose – it has turned yellow and you can’t see through it anymore to read the gauge. Meanwhile, it is not in an enclosed compartment, so risk of fire or explosion is minimal.
Dave
