Hobart 9OC24S Operation Manual page 139

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OPERATION, MAINTENANCE, AND OVERHAUL MANUAL, TM-240A
SELF-PROPELLED GENERATOR SET, SPEC. NO. 5381A
The quality of fuel oil used in the diesel engine is a major factor in engine performance
and life. Fuel oil must be clean, completely distilled, stable , and non-corrosive.
The Cummins engine has been developed to take advantage of the high energy con-
tent and generally lower cost of No. 2 Diesel Fuel. The engine will also operate
satisfactorily on No. 1 fue I. If other fuels are being considered, refer to the
Cummins Operation and Maintenance Manual for fuel specifications and recommended
fuel oil properties.
B. Fuel Filter
A double element fuel filter is located between the fuel source and the pump. Its
function is to remove foreign material from the fuel before it enters the fuel pump.
The filter operates under vacuum.
E lements are the "throw-away" type, in which
the case and element are made as one disposable part. (See Fig. 11.)
(1) Check fuel filter restriction
The most accurate method of determining filter change requirement and deter-
mining change period is by measuring the fuel restriction. As foreign material
accumulates in filter elements, fuel flow becomes more and more restricted,
and vacuum pressure in the fuel inlet line between the filter and pump rises.
Check the degree of filter restriction as follows:
(a) Connect a vacuum gage in the in let fuel I ine at the pump. An adapter
will be required.
NOTE: A vacuum gage No. ST-434, with special adapter, is
available from Cummins Engine Company.
(b) Operate the engine at governed speed and under fuel load. If the gage
indicates 8 to 8.5 In Hg (inches of mercury), elements require changing
(or there are other sources of restriction). When filter restriction becomes
great enough to increase vacuum reading to 10 or 11 In Hg, the engine
will lose power.
(2) Changing fuel filter elements
Change elements after each 400 hours of operation unless a restriction test
indicates the time period should be extended.
(a) Unscrew element (4, Fig. 11) and discard.
NOTE: The elements should be removable by hand. If not, there are
several types of filter element removal tools.
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