Today I declared the tank leak free.... Here is how I pressure tested my tank.
I found this plug that is intended to be used for pressure testing household plumbing and it fits the fuel tank filler port perfectly. It was $8 at Lowes.
The only problem is that it leaks like a screen door around the center bolt. I tried everything to stop the leak. Put grease on the seals and everything else I could think of. Nothing helped!
Then I had an idea....
I cut a balloon like this.....
And stretched it over the fuel filler neck. Ensured there were no wrinkles or creases.
Then shoved the plug into the port and tightened. This worked perfectly! Stopped the leak path up thru the center of the plug. The balloon conforms to the shape of the inside of the plug and forms an air tight membrane.
I used an old fashioned U tube water manometer and a digital manometer to monitor the pressure in the tank.
After three days of watching the pressure, I declared it leak free. The ambient temp and baro does cause the pressure to rise and fall but on consecutive days I checked it at around the same temp and corrected for the minor changes in baro and the pressure remained constant.
I also soaked the tank in soapy water several times looking for any signs of bubbles and found none.
I cut a balloon like this.....
