Diamond DA 40 Flight Manual page 146

Normal Operating
Procedures
5. Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . as required
6. Fuel tank selector . . . . . . . . . . . . . . . . . . . . as required
7. Electrical fuel pump . . . . . . . . . . . . . . . . . . . ON at high altitudes
Operation at high altitudes with the electrical fuel pump OFF
may cause vapor bubbles, resulting in intermittent low fuel
pressure indications, sometimes followed by high fuel flow
indications.
While switching from one tank to the other, the electrical fuel
pump should be switched ON.
END OF CHECKLIST
Page 4A - 30
CAUTION
Rev. 8 01-Dec-2010
(max. difference 10 US gal
with Standard Tank,
8 US gal with Long Range
Tank)
NOTE
DA 40 AFM
Doc. # 6.01.01-E