Cub Cadet M48 - Manual (Page 27)

M48 Tank
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10. KOHLER EFI
Fuel injection is nothing new. The Wright flyer that
made history above the dunes at Kitty hawk, North
Carolina was fuel injected. That was a hundred years
ago this past summer. That system was only slightly
more complex than a cam-driven Windex bottle. All
diesel engines are fuel injected, though the principles
of operation are considerably different.
Electronic fuel injection is not an especially recent
development either. In 1956, Chrysler marketed the
first car with electronic fuel injection. The fuel injection
system used was made by Bendix, and was called
“The Bendix Electrojector System”. It was operated by
a large Electronic Control Module that took up most of
the trunk. The ECM used relatively delicate tubes,
generated a lot of heat, and was susceptible to mois-
ture, temperature changes, vibration, and shock. Most
of these systems were discarded, and the cars retrofit-
ted with carburetors.
There were mechanical gasoline fuel injection systems
on the market before the Bendix system was intro-
duced. Rochester and Bosch were fairly prominent.
The auto industry made the transition to electronic fuel
injection in the 1970s and 80s, in response to emission
control and fuel economy standards.
Even the best-tuned carburetion system only offers and
approximation of the correct fuel mixture for any given
operating condition. They can be tuned to provide
“sweet spots”, but generally cannot maintain an ideal
mixture for all speeds, loads, temperatures, and condi-
tions.
Carburetors also cost efficiency by “working” the air.
the venturi effect that is used to atomize the fuel
requires a pressure drop within the throat of the carbu-
retor. The venturi that creates this pressure drop is a
partial obstruction of the path into the engine.
Until recently, the advantage offered by fuel injection
have not been worth the expense that they add to out-
door power equipment. Fuel injection systems have
become less expensive and more dependable in the
past two decades. At the same time, commercial turf
equipment in specific, and outdoor power equipment in
general have become more sophisticated and more
expensive. Performance and expectations have
improved. The final factor is the increase in the price of
fuel.
All of these factors combine to make EFI worthwhile for
some applications. The improved fuel economy
reduces fuel expense for heavy (Commercial) users. It
also increases range, requiring fewer stops to replenish
fuel.
10.1. For 2004, one model of TANK will be offered
with a Kohler 28 H.P. EFI engine. That unit is a
60” Wide-Track model. That model is built on
the widened M72 frame, but features a 60” deck.
10.2. The fuel injection system used on the the Kohler
powered TANK uses a high pressure electric fuel
pump. The pump generates 3 bars. of pressure
(roughly 40 PSI.), and is capable of moving 25
liters per hour of fuel. This is more fuel volume
than the engine will consume, but it is necessary
in order to maintain pressure under all fuel
demand conditions.
10.3. Because there is more fuel supplied to the injec-
tors than the engine will consume, return lines
route the excess volume back to the fuel tanks.
See Figure 10.3.
10.4. The fuel lines from each tank Tee into a single
line that feeds the fuel pump. See Figure 10.4.
Figure 10.3
Left fuel tank
(1 of 2)
Fuel pick-up
and valve
Fuel return line
Figure 10.4
From left tank
From right
tank
To pump
From pump
to filter