Thanks for the reply.
I did a pretty thorough inspection of the tank the last time I had it off and could find no evidence of a crack anywhere. It seems that the grommets I've tried are just a hair too small in diameter. The fit is just not snug enough to the tank opening, even with the gas line nipple installed.
Something that should be simple really being a pain mainly due to replacements not being correct size.
You say: The fit is just not snug enough to the tank opening,
even with the gas line nipple installed.
I've seen that on some plastic tanks, especially on the large rear tanks on lawn tractors.
Really aggravating, because the replacement grommets just will not seal good
when the OEM gas line nipple is installed.
At times I've installed a slightly large push in nipple so as to force the grommet out larger and get a better seal. I usually used brass nipple and then sometimes have to use 1/4 inch plumbing fitting to get a 90 or a 1/4 inch pipe collar and another nipple to get to the gas line connection.
Main thing is I do testing BEFORE re-installing the tank. Appears that wrong size metric is being used as the replacement for the OEM???????????
I've felt your pain.