Ran into an interesting problem the other day as i was trying to diagnose an engine flameout issue for a fellow racer. The engine was a x7 strapped to a 9853ss. would run great on the box and as soon as we through it down it would bog down and die within the first few corners. Checked and pressure tested entire fuel system then cleaned and flushed. Pressure tested carb then cleaned and flushed. Tore down engine for inspection and then assemble. Blew 125psi through all openings on pipe. Everything checked out ok so i was crossing my fingers thinking i may have flushed gunk out of fuel system. Guess what same sh!t. After scratching my head for a bit, decided to try another 9853 pipe and VIOLA! Looked inside pipe and thought i saw something in the bottom hole of chamber but unable to see clearly. took pipe and slammed it on table and then it popped loose. It was a washer for countersunk screw blocking half of one of the four holes leading to the second chamber causing tons of pressure to be forced into tank when engine was under load.
So PLEASE save yourselves(or your engine guy) the time and headache and keep your pipes in ziploc bags!