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FUEL
SY STENl
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This section is included mainly for the benefit of overseas users, and for those in out-of-the way places.
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As dcscribed, the maintenance and repair operations are made to appear quite simple: in
reality. the risk of amistake occurring which would cause damage to costly parts, is such as to make it
inadvisable for any but experts to undertake the work.
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the lift pump is removed and a blanking plate
fitted in its place.
The lift pump is of the simple spring-returned
plunger type. It is driven by one of the cams on
the camshaft of the fuel pump. on the side of
which it is fitted. It is shown in Fig. 5.1.
A hand primer is fitted, Fig. 5.1, for use if tlle
supply of fuel from the tank has at any time failed,
To use this primer unscrew me handle, which
is free to lift, and then pump by hand until the
pipes, lift pump and fuel pump are ruIl of fuel oiJ.
To ensure that this is so, proceed as instructed
on page 5.6.
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The principal components of tbe equipment for
delivering the fuel oil to tbe engine cylinders are:
filters, fuel lift pump, fuel pump and atomisers.
Tbe fuel lift pump ., lifts" tbe fuel from tbe
tank to tbe fuel pump which conveys it in measured
quantities, and at appropriate intervals, to the
atomisers.
Tbe normal course of tbe fuel from the tank
to the engine is by way of : first, the fuellift pump,
tben tbe paper element type fi1ter. tbe fuel pump
and the atomisers.
On certain installations the fuel system is
gravity red, and therefore no fuel lift pump is
fitted. Tbe fi1ter system in these applications
~onsists of a water trap and a paper element type
filter.
Two conditions are essential for efficient opera-
tion.
First, that the fuel oil should he clean, free from
water, suspended dirt, sand, or other foreign matter
and should conform to the following specification:
Britisb Standard 2869 (1957) Class A.
Second, that tbe fuel reaches the fuel pump
in a perfectly clean state.
Fuel should he filtered before entering the tank.
Given these conditions, ninety per cent at least
of potential engiDe troubles would be eliminated.
The attention of tbc operator is, on that account,
eamestly directed towards those paragraphs of
this Manual which refer to the care and up keep
of tbe filtering apparatus.
The FueJ Lift Pump.
The Cue! lift pump is fitted in pressure red
systems oniy. In the case of gravity red systems,
Fuel Pump.
The fuel pump is an instrument of precision.
lts working parts are made to extremely fine limits
and mishandling in any shape or form, or the
entry of the smallest particle of dirt into its
working parts, may damage it and diminish its
accuracy of operation. Hence the importance of
ensuring that the fuel is thoroughly fi1lered before
the pump is reached.
When fitting a new or replacement fuel pump,
remove the pump inspection cover and pour suffi.
cient engine oil into the spring chamber until oil
comes out of the oil over.low. Refit the inspection
cover.
Thereafter, check the oil level and top up with
fresh oil when necessary every 100 hours or as
of ten as is necessary to maintain the correct leve!.
The outside of the pump should be cleaned before
removing the inspection cover to ensure dirt does
not enter thc pump.
Refer now to Fig. S.ll, the sectional Jrawing
of the fuel pump.
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