I replaced the clunk with a dubro tank filter ( clunk). $2.10 + tax. Only a few bubbles now and it runs decently.
The problem is you have to go with a 3 line system - vent - fill - supply. I am going to try to fill with the vent
and with the supply tube open. And then drain with the supply with the vent line open. Dubro says not to run
fuel thru the filter in reverse. Next question is how to get the clunk to go to the front of the tank. I have two
h9 tanks and one world models tank and all three, the clunk is allways near the rear of the tank. I assume if you
have the nose down and at full throttle ( which seldom happens ) its dead stick time.