Fill the tank about 1/2 full then perform nose up and nose down tests.

Nose up the engine should continue to run through all throttle positions.


Nose down tends to be problematic, as often the clunk gets uncovered.



We tend NOT to let the clunk travel forward with the fuel, which has repercussions...


Unforuntately because if this the clunk can become exposed when you run with 1/2 tank or less in a nose down attitude.


Watch the fuel tubing as you run the engine nose down. Look for air in the lines.


The ideal situation is of course that the engine continues to run and idle through all attitudes for any length of time up to an empty tank.




Also remember that in the air the engine runs leaner than on the ground...

Couple this with an occasional air bubble, and you can get unwanted deadsticks.