Pub. No. EE14E-11130

SERVICE MANUAL CONSTRUCTION& OPERATION

VP44

FOREWORDThis service manual describes the constructionand operation of the VP 44 (Radial plungerdistributor type fuel injection pump).This manual is intended for use by vehiclemaintenance technicians or persons with anadequate knowledge of injection pumps.

The contents of the manual, includingillustrations, drawings and specifications werethe latest available at the time of printing.The right is reserved to make changes inspecifications and procedures at any timewithout notice.

Tokyo, Japan

CONTENTS

PageCOMPONENT OUTLINE ........................ 1

1. OUTLINE ................................................ 1

2. FEATURES............................................. 2

3. SPECIFICATIONS .................................. 3

4. FUEL SYSTEM ....................................... 4

5. SYSTEM CONTROL DIAGRAM ............. 7

6. CONTROL UNIT SYSTEM

CONTROL DIAGRAMS ......................... 8

CONSTRUCTION ................................... 9

1. EXTERNAL VIEW................................... 9

2. CROSS-SECTIONAL VIEW ................. 10

3. EXPLODED VIEW ................................ 11

4. CONSTRUCTION ................................. 12

OPERATION ........................................ 21

1. LOW PRESSURE FUEL CIRCUIT ....... 21

2. HIGH PRESSURE FUEL CIRCUIT ...... 23

3. TIMING CONTROL ............................... 29

4. ANGULAR ENCODER ......................... 34

5. PUMP CONTROL UNIT........................ 35

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COMPONENT OUTLINE

With radial plunger distributor type fuel injectionpumps, the fuel is pressurized by a radialplunger high pressure pump (with 2 or 3cylinders, depending on the number of enginecylinders) positioned axially to the driveshaft.Fuel injection quantity and timing are preciselycontrolled by two electronic control units.A high pressure solenoid valve and a TCV (atimer) are controlled by a pump control unitinstalled at the top of the pump. This controlunit works together with a second control unit,ie, the engine control unit (which detects suchvehicle information as engine speed andaccelerator pedal position), in a dual control unitsystem to ensure high reliability.

1. OUTLINE

Instead of utilizing the previous face cam, theradial plunger distributor type fuel injection pumputilizes a cam ring to enable fuel injection at highpressures, making it suitable for small, highspeed direct injection diesel engines.This pump was developed to provide the mostsuitable fuel injection quantity and injectiontiming to satisfy the demand for engine reliability,driveability, low smoke, low noise, high outputand cleaner exhaust emissions.

Pump control unit

Radial plunger high pressure pump

High pressure solenoid valve

Driveshaft

P-VP4C-001

TCV

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COMPONENT OUTLINE

2. FEATURES[1] High pressure injectionThe radial plunger distributor type injectionpump can generate pressure of 100 MPa{approx 1,000 kgf/cm2} demanded by the small,fuel efficient, high pressure, high speed directinjection diesel engines.[2] High pressure atomization of fuel

injected from the nozzleThrough high pressure injection of fuel, the fuelinjection from the nozzle is atomized at highpressure with a high penetrating force (the fueldroplets penetrate further) and with greaterdispersion and distribution (mixing with air isimproved) so that combustion is improved. Thiscontributes to cleaner emissions.[3] Optimum fuel injection systemHigh speed control of fuel injection quantity andfuel injection timing suitable for the engine isperformed by the control unit, enabling lowerfuel cost and high output.[4] Improved enduranceThe components used in the pump are veryresistant to high pressure, ensuring improvedendurance.[5] Improved engine matchingAs fuel injection to the engine can be controlledfor each cylinder, matching to the engine isimproved.[6] Improved reliabilityAs a dual control unit system with both an enginecontrol unit and a pump control unit is used, thecontrol system is extremely reliable.

[7] Improved power performanceAs the optimum fuel injection quantitycorresponding to accelerator position iscontrolled by the control unit, increased torquein low accelerator pedal positions is possible,enabling improved power performance.[8] Decreased smoke at accelerationWhen fuel injection is increased to increaseengine power at acceleration, smoke is usuallygenerated by the excess fuel. The VP44 fuelinjection pump, however, accurately controlsfuel injection quantity even in this range toprevent the generation of smoke withoutadversely affecting acceleration.[9] Additional devices are unnecessarySuch addit ional devices as the boostcompensator and the aneroid compensator areunnecessary as compensation is made by thecontrol unit based on signals from each sensor.This results in less ‘clutter’ around the injectionpump.[10] Self diagnosis functionThe system includes a self diagnosis functionwhich displays error codes to facilitate thediagnosis of malfunctions.

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COMPONENT OUTLINE

3. SPECIFICATIONSItem

Injection pump typeApplicable vehicles

Applicable number of engine cylindersDirection of rotationDrive methodInjection performance

Maximum pump pressurePlunger diameter x number

Maximum liftMaximum plunger speedMaximum allowable drive torque

SystemMinimum drive voltageMaximum high pressure solenoidvalve currentControl unit type

Battery specificationStandard performance

Standard control method

Timing feed backCompensation for variation betweenpump fuel injection quantitiesTimer advance angle range

Pump sizeWeight

SpecificationsVP44Passenger vehicles, recreational vehicles, small andmedium sized trucks (less than 1 / cylinder)4 cylinders, 6 cylindersClockwise / counter clockwiseToothed belt, gear, chain

100 MPa {approx 1000 kgf/cm2}4 cylinder: φ6.5 mm x 2, φ7 mm x 2, φ7.5 mm x 26 cylinder: φ7 mm x 3, φ7.5 mm x 33.5 mm1.9 m/second: 1000 r/min200 N.m {20.4 kgf.m}: 3 holed flange260 N.m {26.5 kgf.m: 4 holed flange(Maximum drive torque necessary under actual usageconditions: 150 N.m {15.3 kgf.m} limit)

6V≦20 A

Engine control unit, pump control unit(dual control unit system)12V specification, 24V specification

Fuel injection quantity control: high pressure solenoidvalve, time controlInjection timing control: TCV duty solenoid system,hydraulic timerCam position feed backPump EPROM, multi point compensation

Maximum advance angle: 15゜Identical to COVEC-FApprox 8.0 kg

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COMPONENT OUTLINE

(1) Fuel piping systemCentering around the radial plunger distributortype fuel injection pump, the fuel piping systemconsists of a fuel tank, a feed pump, a fuel filter,nozzle holder assemblies and the pipingconnecting these components.(2) Fuel intakeThe fuel in the fuel tank is supplied to theinjection pump through the fuel inlet by the feedpumps in the fuel tank and the injection pump,after first passing through the fuel filter.The fuel filter is installed to filter the fuel, andalso has a sedimenter in the bottom to separateany water from the fuel.(3) Regulating fuel feed pressure and

delivery pressureThe fuel taken in at the fuel intake port ispressurized by the feed pump inside theinjection pump, and is then supplied to theplunger chamber through the high pressuresolenoid valve’s valve needle, which controlsthe direction of fuel flow.

4. FUEL SYSTEM[1] Fuel system schematic

Fuel tank

Feed pump

Fuel filter

Radial plunger distributortype fuel injection pump

Low pressure pipe

Nozzle holder assembly

Engine controlunit

P-VP4C-002

High pressure pipe

Pump control unit Overflow valve

At this time, the fuel pressure is greatest inproportion to pump rotational speed. When itexceeds a specified pressure, excess fuel isreturned to the intake side through the regulatingvalve.(4) Fuel pressurizationThe fuel delivered to the plunger chamber ispressurized by the radial plungers.(5) Determining the optimum fuel injection

quantity and fuel injection timingThe optimum quantity of high pressure fuel ispressure fed to the nozzle holder assembly atthe optimum timing by the high pressuresolenoid valve and the TCV (timer) controlledby the pump control unit.

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COMPONENT OUTLINE

[2] Injection pump fuel intake system

[3] Injection pump fuel pressure feed system

Engine control unit

Fuel intake

Pump control unit

Feed pump

Regulating valve

Overflow valve

High pressuresolenoid valve

Constantpressurevalve

Radial plungerhigh pressure pump

Distr ibutor head

P-VP4C-003

P-VP4C-004

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COMPONENT OUTLINE

[4] Fuel pressurization control

P-VP4C-005

Accumulatordiaphragm

Diaphragmchamber

Overflow valve

Feed pump

Regulating valve

TCV

To feed pump intake

Servo valve

Hydraulicstopper

Timer pistondrive fuelcharge

Timer piston

High pressuresolenoid valve

Constantpressurevalve

Radial plunger

Valve needle

High pressurepassage

Timer pistondrive fuel return

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COMPONENT OUTLINE

5. SYSTEM CONTROL DIAGRAM

P-VP4C-006

Engine speed(crank shaft)

Accelerator pedal

Idle switch

Boost pressure

Air flow volume

Air temperature

Cooling watertemperature

Vehicle speed

Cruise controloperation panel

Brake

Clutch

Air conditioner

Beginning ofinjection

+12V (24V)

Engine control unit

Power supply

Atmospheric pressure sensorSignal inputSignal evaluation

Signal processing・ Fuel injection quantity・ Beginning of pressure feed・ EGR・ Boost pressure・ Vehicle speed・ Engine load・ Monitor・ Minimum function

maintenance・ Calibration

Power outputSignal output

InterfaceDiagnosis

Radial plunger distr ibutor typeinjection pump

Pump control unit

+12V(24V)

CAN

DZG

MAB

LGS

EPC

EPC

Option

EGR valve

Turbo charger

A/C compressor

Diagnostic lamp

Diagnosticrequirement

Service tester

CAN

AutomatictransmissionEngine control unit

CAN: Control area networkDZG: Crankshaft speedMAB: Solenoid valve switch OFFLGS: Low idle signal

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COMPONENT OUTLINE

6. CONTROL UNIT SYSTEM CONTROL DIAGRAMS[1] Block diagram

[2] Circuit diagram

Engine control unit(ECU)

Pumpcontrol unit(PCU)

Fuel injectionpump(mechanicalsection)

Injection timing

Injection quantity

Response signal

Additionalsignals

Engine speed

Accelerator pedal

Air temperature

Boost pressure

Air flow volume

Others

Sensors

Additionaloperations

To high pressure solenoid valve

Timer controldevice

Cam ring rotational angle

High pressuresolenoid valve

To timer control device

Self diagnosis / interface / signal

Engine speed(crank)

Accelerator pedalIdle switch

Engine control unit Pump control unit

Pump speed

Injection quantity

Injection timing

High pressuresolenoid valve

CAN

MAB

DZG

High pressuresolenoid valve

P-VP4C-007

CAN: Control area networkMAB: Solenoid valve switch OFFDZG: Crankshaft speed

Fuel temperature