McCulloch B33 P Operator Instructions Manual page 10

Do not mix more than one month's supply of fuel
at a time.
If the unit is not used for some time the fuel tank
must be emptied and cleaned.
a
WARNING:
Fueling
a
WARNING:
Do not smoke or place hot objects near fuel.
minutes before refueling.
any excess pressure is released gently.
Tighten the fuel cap carefully after refueling.
and source before starting.
Clean the area around the fuel cap. Contamination in
the tank can cause operating problems.
10