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FUEL FILTERS
Two fuel filters are used in the fuel supply line to the engine. One fuel filter is located in the
supply line between the fuel tank and fuel pump. This filter helps to protect the fuel pump from
any large debris that may be present in the fuel tank. Another fuel filter is located in the supply
line between the fuel pump and the engine. This filter helps to protect the fuel injectors from any
small debris. These filters need to be changed every 100 hours and possibly sooner if fuel
comes from drums, unknown sources, or old tanks.
FUEL PRESSURE REGULATOR
The LT4 engine is supplied with a fuel pressure regulator to
provide a constant pressure to
the high pressure pump, fuel rail, and injectors. The pressure regulator is preset at the
factory. The fuel pressure must
be between
65-67 psi
before running the engine. Contact
your service dealer or KEM Equipment
if you have fuel pressure questions.
FUEL TYPE
The LT4 engine requires a minimum of 92 octane premium unleaded gasoline. Fuel with an
octane ranking of 92 or higher should be used. Lower octane fuels will greatly reduce overall
engine performance and may cause the engine to operate at reduced RPM’s. Maximum ethanol
content is 10%. Do not use fuel with a higher content of ethanol or E85.
FUEL QUALITY CHANGES
NOTE:
Sudden changes in fuel quality, including those due to geographical regions, may effect engine
operation.