Cub Cadet M48 service manual Kohler EFI

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.

M48 Tank

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.

Left fuel tank (1 of 2)

Fuel pick-up and valve

Fuel return line

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.

From left tank

From right tank

To pump	From pump
	to filter

Figure 10.4

23