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d. Threaded fasteners used to secure the fuel rail are Critical Fasteners, see T.8.2 IC.6.2 High Pressure Injection (HPI) / Direct Injection (DI)
IC.6.2.1 Definitions
a. High Pressure fuel systems - those functioning at 10 Bar pressure or above
b. Direct Injection fuel systems - where the injection occurs directly into the combustion system
Direct Injection systems often utilize a low pressure electric fuel pump and high pressure
mechanical “boost” pump driven off the engine.
c. High Pressure Fuel Lines - those between the boost pump and injectors
d. Low Pressure Fuel Lines - from the electric supply pump to the boost pump IC.6.2.2 All High Pressure Fuel Lines must:
a. Be stainless steel rigid line or Aeroquip FC807 smooth bore PTFE hose with stainless steel reinforcement and visible Nomex tracer yarn. Equivalent products may be used with prior approval.
b. Not incorporate elastomeric seals
c. Be rigidly connected every 100 mm by mechanical fasteners to structural engine components such as cylinder heads or block
IC.6.2.3 Any Low Pressure flexible Fuel Lines must be one of:
Metal braided hose with threaded fittings (crimped on or reusable)
Reinforced rubber hose with some form of abrasion resistant protection IC.6.2.4 Fuel rail mounting requirements:
a. The fuel rail must be securely attached to the engine block or cylinder head with brackets and mechanical fasteners. Hose clamps, plastic ties, or safety wires do not meet this requirement.
b. The fastening method must be sufficient to hold the fuel rail in place with the maximum regulated pressure acting on the injector internals and neglecting any assistance from cylinder pressure acting on the injector tip.
c. Threaded fasteners used to secure the fuel rail are Critical Fasteners, see T.8.2
IC.6.2.5 High Pressure Fuel Pump – must be rigidly mounted to structural engine components such as the cylinder head or engine block.
IC.6.2.6 Pressure Regulator – must be fitted between the High Pressure and Low Pressure sides of the fuel system in parallel with the DI boost pump. The external regulator must be used even if the DI boost pump comes equipped with an internal regulator.