MoTeC M8 - Manual (Page 25)

MoTeC Installation 23
Fuel Rails
The fuel rails must be free of any debris that could block the injectors. Welded
fuel rails can often cause a problem unless they have been properly treated to
remove all scale and debris and even then they may corrode and cause
problems. Aluminium fuel rails mounted directly on the injectors are
recommended as they do not suffer these problems.
The fuel rails must have sufficient volume to minimise fuel pressure pulsation
and resonance problems.
Fuel Pressure Regulator
The fuel pressure regulator maintains constant fuel pressure to the injectors
which is necessary to ensure constant metering of the fuel. Any variation in
the fuel pressure will cause a corresponding mixture change.
The fuel pressure regulator should be mounted at the end of the fuel rail so
that fuel is always flowing through the rail. This helps to avoid vapour locks.
Adjustable pressure regulators are available.
If using Manifold Pressure Load Sensing
Connect the regulator port to the plenum, this ensures that constant pressure
is maintained across the injectors.
Note that this will cause the fuel pressure required from the pump to increase
as the manifold pressure increases.
If using Throttle Position Load Sensing
Leave the regulator port open to the atmosphere, unless the MAP sensor is
connected to the manifold as is recommended when using idle speed control,
in which case the regulator port should be connected to the manifold.
Fuel Injectors
The fuel injectors meter the fuel by opening for a short but defined time either
once per engine rev or once per engine cycle in the case of sequential
operation.
Group Fire Operation
All injectors are fired together once per engine rev or in two groups 180
degrees apart once per engine rev.