4M40 DIESEL ENGINE SHOP MANUAL Fuel and Engine Control Caterpillar

Specifications

Structure and Operation

Fuel System (Flow of Fuel)

* The feed pump, which is driven by the driveshaft of the injection pump, draws up the fuel from inside the fuel tank and sends it through the fuel filter, where dust and other impurities in the fuel are filtered out.

* The filtered fuel is then sent to the injection pump, where it is pressurized and sprayed out through the injection nozzles into the combustion chamber.

* The leak-off fuel from the injection nozzles returns to the fuel tank through the leak-off hose and fuel return pipe.

* When the internal fuel pressure of the injection pump exceeds the limit, the overflow valve opens to allow part of the fuel to return to the fuel tank.

Fuel Filter

* The fuel filter removes impurities in the fuel through the fuel filter cartridge and also separates water from fuel.

* The water that has been separated from the fuel collects at the bottom of the fuel filter. A water separator sensor is installed in the fuel filter, which activates the warning lamp on the meter cluster when the water reaches a certain level.

* The water can be drained through the drain port by loosening the drain plug.

* A priming pump is provided at the fuel filter head. The priming pump is used for air-bleeding the fuel system.

Injection Nozzles

* The injection nozzles are of a throttle type, in which the injection starting pressure is determined by the thickness of the adjusting shim.

* When the pressure of the fuel forced into the nozzle by the injection pump (the pressure inside the nozzle tube) presses upon the pressure-receiving surface and overcomes the spring force, the needle valve rises and fuel is sprayed out of the nozzle.

* When the pressure acting on the pressure-receiving surface no longer overcomes the force of the spring, the spring pushes the needle valve up and fuel injection is instantly stopped.

* Any excess fuel passes through the space between the needle valve and the nozzle to the fuel leak-off pipe, and returns to the fuel tank.

Injection Pump

* The injection pump is a compact, lightweight type and has a distribution system that can cope with high revolution operation.

* The distribution system is a type that distributes fuel to each cylinder by a single plunger. Fuel to be distributed is filled within the injection pump and lubricates each part in there.

Injection pump body

* Drive shaft drives feed pump, cam disc and plunger simultaneously. Plunger spring presses the plunger and the cam disc against roller.

* The rotation of cam disc which is driven by drive shaft drives face cam in a rotary movement on roller, creating a reciprocating movement of plunger, which eventually forces the fuel into the cylinder.

Governor

* The rotation of drive shaft is transmitted via drive gear to flyweight holder gear to turn flyweight holder.

* Flyweight holder is supported by governor shaft. The four flyweights installed in the holder open outward due to the generation of centrifugal force.

* The movement of flyweights pushes governor sleeve, and governor lever toward the right as illustrated.

* Governor lever consists of corrector lever, tension lever, and start lever.

Automatic timer

* The automatic timer is a hydraulic type and consists of timer spring, timer piston and roller holder pin.

* Timer piston makes a reciprocating movement inside the injection pump housing. At the end of low pressure side, timer spring is installed and at the end of high pressure side, fuel pressure prevails. The piston is activated by alternating changes of force between the two sides.

* Roller holder pin is installed between timer piston and roller holder and converts the reciprocating movement of the piston into the rotary movement of the holder.

* As roller holder moves its position, the timing of the lobe of cam disc going over roller changes, and this controls the fuel injection timing.

Feed pump

* The feed pump is a vane type and consists of rotor installed inside the injection pump chamber, vanes and liner in the pump housing.

* Rotor is fixed to pump drive shaft and has four vanes. Liner is installed eccentric to rotor. Due to this arrangement, when rotor rotates, vanes spin outward due to the centrifugal force generated and adhere to the inner side of liner, creating four chambers partitioned by the vanes. The capacity of the chambers varies as the rotor rotates. When the capacity of the chamber expands, fuel from fuel tank is sucked in, and as the capacity contracts, fuel is compressed to be forced out into the injection pump chamber.

* Regulator valve opens when the pressure for fuel delivery generated by the feed pump is higher than the standard value; in the process of increasing the engine revolution, this lets the fuel return to the inlet port of the feed pump, thus controlling the fuel pressure in the injection pump chamber within the standard values.

Fuel-cut solenoid valve

* The starter switch turns the fuel-cut solenoid valve ON or OFF electrically opening or closing the valve for fuel passage which is connected to inlet port of plunger barrel.

Starter switch at ON or S

Fuel-cut solenoid valve is electrically active and magnetized to push up spring and armature, opening fuel passage.

Starter switch at ACC or (OFF) or LOCK

Demagnetization takes place by which action armature is pushed down by spring, and fuel passage is closed and no fuel is delivered to plunger, making the engine inoperative.

Troubleshooting

General Inspection and Adjustment

Inspecting and Adjusting Fuel Injection Timing

Service standards (Unit: mm)

Tightening torque (Unit: N·m {kgf·m})

Special tools

[Inspection]

* Remove the rocker cover.

* Bring the No. 1 or No. 4 cylinder piston to the top dead center (TDC) on the compression stroke by the following procedure.

* Rotate the crankshaft in the illustrated direction so that the notch on the crankshaft pulley is aligned with the "0" mark on the timing gear case.

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* Do not turn the crankshaft pulley in the wrong direction (counterclockwise), as this may cause damage to the tensioner that is adjusting the tension of the timing chain on the idler sprocket and cam sprocket. If you turn the crankshaft pulley in the wrong direction by mistake, remove and reinstall the tensioner.

* This will place either the No. 1 or No. 4 cylinder piston at TDC on the compression stroke. The cylinder with the indentation in the hexagonal portion of the camshaft facing upward has its piston at TDC. Rotate the engine by one full turn to swtich the TDCs of the No. 1 and No. 4 cylinder pistons.

* Mount the dial gauge on
by the following procedure.

* Turn the push rod until it is projection out of the body by 12 mm.

* Insert and slowly push the dial gauge into the holder. Once the plunger of the dial gauge just touches the push rod causing the needle to begin to move, lock the dial gauge in the holder with the screw.

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* Lock the dial gauge before its needle passes 0.5 mm.

* Remove the distributor head bolt and gasket from the injection pump.

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* Do not leave the gasket on the injection pump, as this will lead to incorrect measurement by .

* Screw
into the injection pump until the needle of the dial gauge starts moving.

* If the dial gauge is facing in a difficult-to-read direction, adjust the direction by turning
an angle not exceeding 360°.

* Turn the crankshaft in the illustrated direction (clockwise) using
so that the No. 1 cylinder piston is at 30°BTDC.

* Set the needle of the dial gauge on
to zero.

* Make sure that the dial gauge needle does not move when the crankshaft pulley is moved clockwise or counterclockwise by 2 to 3°.

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* Do not turn the crankshaft pulley counterclockwise by more than 2 to 3°, as doing so may cause damage to the tensioner on the timing chain.

* Turn the crankshaft pulley clockwise. With the No. 1 cylinder piston at the fuel injection timing position, measure the plunger lift using the dial gauge on
.

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* The timing mark on the timing gear case is graduated in 2-degree increments.

* If the measurement is not within the standard value range, adjust the plunger lift by the following procedure.

[Adjustment]

* Loosen the union nuts 1, bolt 2, and nuts 3 in that order.

1 Union nuts (one each on four injection pipes)

2 Bolt (injection pump mounting bolt at one place)

3 Nuts (injection pump mounting nuts at two places)

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* When loosening the union nut, hold the delivery valve holder with a wrench to prevent it from turning. * Loosen the bolt and nuts; do not remove them.

* Tilt the injection pump to the right and to the left so that the dial gauge needle points a value within the standard value range.

A: When the dial gauge needle points a value exceeding the standard value range

B: When the dial gauge needle points a value below the standard value range

* Carry out the inspection procedure again and check that the plunger lift is within the standard value range.

* Tighten the nuts 1, bolt 2, and union nuts 3 in that order.

1 Nuts (injection pump mounting nuts at two places)

2 Bolt (injection pump mounting bolt at one place)

3 Union nuts (one each on four injection pipes)

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* When tightening the union nut, hold the delivery valve holder with a wrench to prevent it from turning.

* Remove
.

* Replace the gasket with a new one, and install and tighten the distributor head bolt to the specified torque.

Inspecting and Adjusting No-load Minimum and Maximum Speeds

Service standards

[Work before inspection and adjustment]

* Before starting the inspection and adjustment, carry out the following preparatory steps:

* Warm up the engine until the engine coolant temperature is approximately 80 to 95°C;

* turn off all lamps and accessories;

* put the lever in neutral;

[Inspection and adjustment]

(1) No-load minimum speed

* Check that the control lever is touching the idling set bolt. Without depressing the accelerator pedal, measure the engine speed.

* If the speed is not within the standard value range, adjust it using the idling set bolt.

* Raise the engine speed to 1400 to 1600 rpm, then remeasure the no-load minimum speed.

(2) No-load maximum speed

* With the control lever touching the full speed set bolt, measure the engine speed.

* If the speed is not within the standard value range, adjust it using the full speed set bolt.

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* Do not disturb the setting of the full load stopper bolt. * Check that the engine neither stops nor hunts when the control lever is moved from the full speed position to the idling position.

Inspection of Fuel Leakage

* Check the fuel tank, fuel filter, injection pump, injection nozzles and fuel piping for fuel leakage. If any leakage is found, replace the leaking parts and tighten the loose connections to the specified torque. If rubber part of a clamp is deteriorated, replace the clamp and tighten it to the specified torque.

Inspection of Injection Pipe and Fuel Pipe Mounting Clamp

Tightening torque (Unit N·m {kgf·m})

* Visually check the clamp appearance and make sure there is no cracks or damages at the rubber part of the clamps.

* Check for looseness in the clamp mounting bolts and nuts. If there is looseness, tighten the bolts and nuts to the specified torque.

Air-bleeding of Fuel System

Tightening torque (Unit: N·m {kgf·m})

* Loosen the air vent plug of the fuel filter.

* Move the priming pump up and down to pump out the fuel.

* Continue operating the priming pump until the fuel flowing out of the air vent plug is free of air bubbles.

* When no more air bubbles are evident, tighten the air vent plug to the specified torque.

* Operate the priming pump further until a strong resistance can be felt.

* Wipe up any spilled fuel and start the engine.

* Check that there is no fuel leakage.

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* Fuel is highly flammable. Keep it away from flames and sources of heat. * To avoid risk of fire, wipe up any spilled fuel.

Fuel Filter Replacement

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* Fuel is highly flammable. Keep it away from flames and sources of heat. * To avoid risk of fire, wipe up any spilled fuel.

Lubricant and/or sealant

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* Be sure to use only genuine MITSUBISHI filter cartridges. The use of non-genuine fuel filters can cause fuel leakage and fire.

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* Prevent fine dust particles from entering the fuel filter and fuel pipe, as they can cause problems such as faulty fuel injection.

* Clean the fuel filter mounting surface of the fuel filter head.

* Apply a thin coat of engine oil to the fuel filter gasket.

* Screw the fuel filter cartridge into the filter head by hand until its gasket comes into contact with the head. Tighten the cartridge by one further turn.

* Install the water separator sensor, and then air-bleed the fuel system.

* Start the engine, and check that there is no fuel leakage from the gasket.

* Reinstall the fuel filter cartridge if there is any leakage.

Fuel Filter

* Disassembly sequence

1 Fuel hose

2 Drain plug

3 O-ring

4 Water separator sensor

5 O-ring

6 Fuel filter cartridge

7 Fuel filter head

X Non-reusable parts

* Assembly sequence

Follow the disassembly sequence in reverse.

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* Fuel is highly flammable. Keep it away from flames and sources of heat. * To avoid risk of fire, wipe up any spilled fuel.

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Installation procedure

Installation: Fuel filter

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* Be sure to use only genuine MITSUBISHI FUSO filter cartridges. The use of non-genuine fuel filters can cause fuel leakage and fire.

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* Prevent fine dust particles from entering the fuel filter and fuel pipe, as they can cause problems such as faulty fuel injection.

* Clean the fuel filter mounting surface of the fuel filter head.

* Apply a thin coat of engine oil to the fuel filter gasket.

* Screw the fuel filter cartridge into the filter head by hand until its gasket comes into contact with the head. Tighten the cartridge by one further turn.

* Install the water separator sensor, and then air-bleed the fuel system.

* Start the engine, and check that there is no fuel leakage from the gasket.

* Reinstall the fuel filter cartridge if there is any leakage.

Injection Pump

* Removal sequence

1 Fuel leak-off hose

2 Fuel return hose

3 Fuel feed hose

4 Accelerator control cable

5 Water hose

6 Injection pipe

7 Stay

8 Injection pump (See later section)

9 O-ring

X Non-reusable parts

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* Fuel is highly flammable. Keep it away from flames and sources of heat. * To avoid risk of fire, wipe up any spilled fuel. * Dirt and dust in the injection pump can seriously detract from engine performance. To prevent this from happening, fully cover all open joints after removing any pipes or hoses. * Check the injection pipe seat surface for scratches and unevenness before installing the injection pipe. * Do not hold the injection pump by the control lever as this may cause the injection pump to malfunction. * Do not remove the control lever, as this may cause the injection pump to malfunction.

* Have the injection pump serviced by a Bosch service station.

* Installation sequence

Follow the removal sequence in reverse.

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Special tools (Unit: mm)

Removal procedure

Removal: Injection pipe

* Disconnect the injection pipe by loosening the union nut while holding the delivery valve holder.

Removal: Injection pump

* The four injection pump mounting bolts (A and B) are installed in the following ways. Be sure to remove all these bolts to remove the injection pump.

A Installed from timing gear case side, fastening cover as well

B Installed from timing gear case side

Installation procedure

Installation: Injection pump

* Remove the rocker cover.

* Bring the No. 1 cylinder piston to the top dead center (TDC) on the compression stroke by the following procedure:

* Rotate the crankshaft pulley in the illustrated direction so that the notch on the pulley is aligned with the "0" mark on the timing gear case.

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* Do not turn the crankshaft pulley in the wrong direction (counterclockwise) as this may cause damage to the tensioner that is adjusting the tension of the timing chain on the idler sprocket and cam sprocket. If you turn the crankshaft pulley in the wrong direction by mistake, remove and reinstall the tensioner.

* This place either the No. 1 or No. 4 cylinder piston at TDC on the compression stroke. If indentation at the hexagonal portion or an projection on the camshaft is facing upward, the No. 1 cylinder piston is at TDC on the compression stroke. If not, rotating the engine by one full turn places the No. 1 cylinder piston at the TDC on the compression stroke.

* Align indent on injection pump gear with "T" mark on flange plate.

* Insert guide bar on flange plate into guide hole of front plate until right before injection pump gear engages with the idler gear.

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* To ensure the injection pump is installed properly, tighten the bolts with the flange plate pressed firmly against the front plate.

* Make sure that "T" mark on flange plate is align indent on injector pump gear, and insert the injection pump. At this time, indents on the injection pump gear will engage while turning in the arrow directions as illustrated.

Installation: Injection pipe

* Install the injection pipe respecting the same instructions as its removal. (See " Removal: Injection pipe".)

* Disassembly sequence

1 Injection pump gear

2 Flange plate

3 O-ring

4 Key

5 Injection pump

X Non-reusable parts

* Assembly sequence

Follow the disassembly sequence in reverse.

Tightening torque (Unit: N·m {kgf·m})

Lubricant and/or sealant

Special tools

Removal procedure

Removal: Injection pump gear

Installation procedure

Installation: Flange plate

* Install the flange plate by aligning its mating mark with the mating mark on the injection pump.

Injection Nozzle

* Disassembly sequence

1 Injection pipe

2 Fuel leak-off pipe

3 Fuel leak-off pipe gasket

4 Retaining nut

5 Adjusting shim

6 Spring

7 Pressure pin

8 Distance piece

9 Needle valve

10 Nozzle

11 Body

12 Nozzle holder gasket

13 Nozzle gasket

X Non-reusable parts

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* Fuel is highly flammable. Keep it away from flames and sources of heat. * To avoid risk of fire, wipe up any spilled fuel.

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* Remove any carbon deposits from the injection nozzles before disassembling, assembling, or adjusting the injection nozzle assembly. Before disassembling, check the pressure and shape of the spray and inspect the assembly for fuel leakage. Do not disassemble if no defects are evident. * Do not change the needle valve and nozzle combination on each cylinder.

* Assembly sequence

Follow the disassembly sequence in reverse.

Service standards

Tightening torque (Unit: N·m {kgf·m})

Special tools (Unit: mm)

Inspection before removal

Inspection: Injection nozzle

* Connect the injection nozzle to the nozzle tester and carry out the following inspections.

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* Before starting the inspections, operate the lever on the nozzle tester two or three times to bleed out all the air.

(1) Checking the valve opening pressure

* Push down the lever on the nozzle tester at a rate of one to two seconds per stroke. This will cause the pressure gauge reading to rise gradually, and the needle will suddenly deflect. Note the pressure at which the needle starts to deflect.

* If the measurement is out of the standard value range, disassemble the nozzle, clean it, and then adjust it using an adjusting shim.

* Available adjusting shims (thickness): 1.2 mm to 1.7 mm (11 different thicknesses in increments of 0.05 mm)

* If the valve opening pressure is still incorrect after the adjustment, replace the injection nozzle assembly.

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* Do not touch the spray that comes out of the nozzle.

(2) Inspecting the spray condition

* Pump the lever on the nozzle at a rate of about one to two seconds per stroke and keep it spraying continuously.

A Spray in the form of straight line (Good: spray angle at 10° or less)

B Spray angle too large (Bad)

C Spray deviates from centerline (Bad)

D Irregular spray (Bad)

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* Do not touch the spray that comes out of the nozzle.

* Check that no fuel drips from the nozzle after the spray is complete.

* If defects are evident, disassemble and clean the injection nozzle, and then inspect its spray condition once again.

* If defects persist after reinspection, replace the injection nozzle assembly.

(3) Checking for leakage

* Decrease the nozzle pressure to a pressure 1960 kPa {20 kgf/cm²} lower than the first valve opening pressure. Maintain this pressure for 10 seconds and check that no fuel drips from the end of the nozzle.

* If fuel drips are evident, disassemble and clean the injection nozzle, and then perform a leakage test once again.

* If leakage is detected during the reinspection, replace the injection nozzle assembly.

Removal procedure

Removal: Injection nozzle

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* Do not touch the sliding surfaces of the needle valve. If you accidentally touch it, clean it with a cleaning fluid (such as gas oil). * Do not change the needle valve and nozzle combination on each cylinder.

Cleaning procedure

Cleaning: Injection nozzle

* Wash the needle valve and nozzle in a cleaning fluid (such as gas oil), then use
to remove any carbon deposits according to the following procedure.

* Remove carbon deposits from the tip of the needle valve using the clean bar of
.

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* Do not use a wire brush or any hard metallic object for cleaning.

* Clean the carbon deposits in the fuel cavity using the cleaning bar of
.

* Clean the nozzle seat using the cleaning needle of
.

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* Be careful not to scratch the seat.

* Use FUSO CARBON REMOVER to remove any hardened carbon.

* Remove carbon deposits from the injection orifice of the nozzle by inserting the bar of
in the orifice at the tip of the nozzle and turning it. Cleaning needle diameter: 1.0 mm or less

* Clean off any carbon deposits on the exterior of the nozzle using the brush of

Inspection procedure

Inspection: Injection nozzle

* Wash the needle valve and nozzle in a cleaning fluid (such as gas oil) and then put them together.

* Pull up the needle approximately one-third of its entire stroke, and check that it slides down under its own weight. Repeat this test several times, turning the needle valve each time.

If the needle valve does not slide down, wash it once more and carry out this test again. If the needle valve movement is still defective, replace the needle valve and nozzle as a set.