Correct me if I'm wrong here while I remove the dent from my forehead. I struggled mightily over the last couple of weeks with an OS 46LA not running up to speed, but likely solved the problem by cleaning a couple of hairy goobers out of the NVA. What took me so long? Well, I'd been running a filter in the engine fuel feed line, so ruled out a clogged NVA. Wrongo assumption!
The problematic setup: a clunk tank with a muffler pressure feed and a fuel feed only; no third vent. I'd been filling the tank through the fuel feed line (and filter!), with venting provided by the muffler pressure line. It fueled up nicely, so why bother with that third pipe?! Well yes, but the filter was doing me no good (insert "zoot-alohrs" and other choice words here!). So from now on, I'll use that third pipe to fuel the beast, cap it off when done and let the filter work as intended.
Ah, the learning curve of this most fascinating sport!
Mo....