Posted for Don Skeele <dpske@wvi.com>:

Bill,
      I may be oversensitve about Tygon, but a Tygon sight gauge on my 235 became hard  , discolored and shrunk slightly in length in a couple years of operation. Replaced it with Polyurathane tubing wrapped with electrical tape where chaffing could be a problem and have had no problems 9 years later.  A quick check to see is if the Tygon is stiff might be in order.  I run TCP in my fuel tanks/lines which may have presented a different situation..  Anyway, had to say something, hope this might help..  Don Skeele N320J  (503) 769-2563