Rotax 912 i Series Maintenance Manual page 238

SYSTEM DESCRIPTION
FUEL PUMP MODULE
The fuel pump module is available from ROTAX
on request.
The fuel pump module consists of:
Main and additional pump
2 check valves
connecting lines, connecting hoses
sheet metal housing
The main fuel pump is always switched on
during operation of the aircraft engine. The addi-
tional fuel pump is switched on in the event of a
failure of the main pump or for certain flight situ-
ations (e.g. take-off and landing). If a pump is
blocked by dirt, the fuel is sucked in via the
check valves and carried to the engine.
FUEL DISTRIBUTION
The main elements of the fuel distribution
assembly are:
- Air filter
- Throttle body
- Airbox
- Injection system with fuel pressure regulator
assy.
Throttle body
The throttle valve is actuated by using the
throttle lever. The position of the throttle valve is
detected by the throttle potentiometer and the
signal is sent to the ECU. The ECU uses the
sensors to determine the amount of fuel and the
fuel is injected directly into the intake manifold
through the injection valves.
NOTICE
WARNUNG
The throttle valve is set to WOT if no throttle val-
ve is attached. Never start the engine without
connecting a throttle cable.
Effectivity: 912 i Series
Edition 1/Rev. 0
BRP-Powertrain
MAINTENANCE MANUAL
Fuel pressure regulator
The fuel pressure regulator keeps the fuel sys-
tem pressure upstream of the injection valves
constant relative to the intake manifold pressure
(differential fuel pressure). The injection quantity
is therefore only dependent on the activation
time of the injection valves and can be reprodu-
ced using the activation time in all operating con-
ditions. Therefore, the same amount of fuel is
injected per unit time at all pressure ratios.
It is essentially a bypass valve, which opens a
return duct to the tank for the fuel by means of a
spring-loaded diaphragm when the set pressure
is exceeded. The regulator has a vacuum line to
the airbox (reference line) so that the absolute
fuel pressure can be changed proportionally to
the airbox pressure.
Fig. 1
Fuel inlet
Dia-
Intake
Function principle
NOTE: The fuel pressure is 3 bar +/-0.1 bar.
Injection valve
The injection valves are laid out in a redundant
manner and are activated by the control unit so
that they inject alternately.
1-4-2-3 and in the next combustion cycle
5-8-6-7.
Fuel return
manifold
73-10-00
06263
Page 6
July 01/2012