Injector Testing and Fuel Control Systems

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Questions and Answers

What indicates that an injector is operating properly during the 'clunk' test?

The cylinder will fire with a pronounced 'clunk'. (correct)

The cylinder will fire silently.

Fuel will leak from the injector.

The injector control lever will remain stationary.

Which tool is required to perform the injector pressure test?

Special tool #4002 1839 (correct)

Injector alignment tool

Engine compression tester

Carburetor adjustment tool

During the injector pressure test, what should be checked on the engine before applying the test tool?

The air filter must be replaced.

The injector control lever must be lubricated.

The engine fuel lines must be charged. (correct)

The coolant level must be adequate.

What should be done with the injector rack before conducting the injector pressure test?

It should be placed in the full fuel position. Signup and view all the answers

What is the first step during the 'clunk' test for each injector?

Remove the spring clip and clevis pin. Signup and view all the answers

What aspect does the electronic fuel control system primarily regulate?

Both timing and metering of fuel Signup and view all the answers

How does fuel temperature affect fuel injection in an engine?

Different fuel temperatures may alter fuel quantity and timing Signup and view all the answers

Which horsepower output requires the engine to inject fuel differently compared to another output?

4300 horsepower compared to 5000 horsepower Signup and view all the answers

What is one significant benefit of the electronic fuel control system in GM locomotives?

It allows for variable fuel delivery Signup and view all the answers

What is the effect of varying air inlet pressure on fuel injection timing?

Pressure variations require adjustments in fuel timing and quantity Signup and view all the answers

Which of the following fuel temperatures was associated with the 5000 horsepower scenario?

60°F (15.54°C) Signup and view all the answers

What does the electronic fuel control system enable regarding engine troubleshooting?

It is the first computer-aided troubleshooting tool Signup and view all the answers

What function of the injectors can be monitored with the EM2000 locomotive control system?

Fuel temperature Signup and view all the answers

Which measurement is NOT monitored by the EM2000 system?

Engine RPM Signup and view all the answers

Which component has replaced the Woodward governor in the engine's operation?

Engine Control Modules (ECMs) Signup and view all the answers

What specific cooling condition is monitored in the EM2000 system?

Coolant temperature on both banks Signup and view all the answers

Which of the following parameters is related to the engine's load capacity as displayed by the EM2000 system?

LR%MAX Signup and view all the answers

What temperature is monitored for lube oil by the EM2000 system?

Lube oil temperature Signup and view all the answers

Which of the following is NOT a factor monitored concerning engine performance?

Engine braking performance Signup and view all the answers

How is the operation of injector timing monitored in the EM2000 system?

Through electronic interfaces with ECMs Signup and view all the answers

What aspect of fuel management is assessed before and after primary filtration?

Fuel pressure Signup and view all the answers

What is the function of the magnetic pickups in the injection system?

To provide basic timing information Signup and view all the answers

Where are the magnetic pickups located in the diesel engine system?

At the rear coupling disk Signup and view all the answers

What do the timing indicator plates affect in the system?

Electronic signal generation Signup and view all the answers

Which component receives the electronic signals generated by the magnetic pickups?

Electronic Control Module (ECM) Signup and view all the answers

What does the movement of timing indicator plates signify during operation?

Position of the crankshaft Signup and view all the answers

What role does the ECM play in the context of signals from the magnetic pickups?

It interprets and processes the signals Signup and view all the answers

In the described diesel engine system, what is essential for generating an electronic signal?

Timing indicator plates movement Signup and view all the answers

What happens as the coupling disk rotates in this diesel engine system?

Timing plates pass the magnetic pickups Signup and view all the answers

What is the primary purpose of the injection system in this context?

To control fuel delivery and timing Signup and view all the answers

Which series of diesel engines is described in the content?

Model 567, 645 & 710 Signup and view all the answers

What is the function of the Synchronous Reference Sensor (SRS)?

To generate a signal per revolution of the engine. Signup and view all the answers

How does the Timing Reference Sensor (TRS) signal engine speed?

By indicating the movement of the crankshaft through pulses. Signup and view all the answers

What determines the exact timing and duration of fuel injection?

Ambient conditions and engine load. Signup and view all the answers

What was significant about the change in fuel injection timing control?

It is now a software-controlled process. Signup and view all the answers

How often does the SRS generate a signal?

Once per each crankshaft revolution. Signup and view all the answers

What is indicated by each pulse from the TRS?

The crankshaft has moved 10 degrees. Signup and view all the answers

What happens to fuel in the electronic injector during operation?

It continually circulates as supplied by the fuel pump. Signup and view all the answers

Which component reads the timing plates for indexing the crankshaft's position?

Timing Reference Sensor. Signup and view all the answers

What aspect does not influence the timing of fuel injection?

Mechanical wear over time. Signup and view all the answers

What does the engine control computer primarily adjust in modern engines?

The timing and duration of fuel injection. Signup and view all the answers

What is the primary role of the suction strainer in the fuel system?

To remove large debris from the fuel Signup and view all the answers

How frequently should the suction strainer be maintained?

At intervals specified in the Scheduled Maintenance Program Signup and view all the answers

What is the purpose of the M O T valve in the fuel system?

To divert fuel to maintain a constant temperature Signup and view all the answers

What is a characteristic of the gear type fuel pump mentioned?

It ensures adequate fuel supply at all engine speeds Signup and view all the answers

What is a recommended practice for maintaining the fuel tank in high humidity conditions?

Drain the condensate more frequently Signup and view all the answers

Why is it important to keep the fuel system free of foreign materials?

To maintain a smooth injection process Signup and view all the answers

What is the typical fuel temperature maintained by the fuel heat exchanger?

100 degrees F (37.74 Co) Signup and view all the answers

What components are included in the delivery side of the fuel injection system?

Fuel injectors, layshaft mechanism, and control device Signup and view all the answers

Which process is essential for the function of any fuel-injection system?

Simultaneous measuring and timing of fuel Signup and view all the answers

What must be delivered to the injection mechanism as the first step in the fuel injection process?

Fuel Signup and view all the answers

What is the role of the layshaft mechanism in the fuel system?

It synchronizes the timing of fuel delivery. Signup and view all the answers

What does the control device or governor in the fuel delivery system primarily manage?

Fuel pressure and timing Signup and view all the answers

Why is it crucial for fuel measurement to occur in a specific sequence during injection?

To ensure effective fuel combustion Signup and view all the answers

Which part primarily impacts the timing of the fuel delivery process?

Layshaft mechanism Signup and view all the answers

What is a critical factor that affects the operation of the fuel injectors?

Fuel flow rate Signup and view all the answers

What element must be synchronized with the fuel delivery for optimal performance?

Timing of fuel measurement Signup and view all the answers

What is the primary role of the electrically controlled poppet valve during the injection process?

To control the timing of fuel delivery to the injector Signup and view all the answers

When does the fuel become pressurized in the injector during the injection cycle?

After the needle valve at the injector tip unseats Signup and view all the answers

What happens to the high-pressure fuel once injection is stopped?

It is directed back to the fuel pump through the open poppet valve Signup and view all the answers

How does the plunger's downward movement affect fuel flow within the injector assembly?

It allows the poppet valve to open and releases trapped fuel Signup and view all the answers

What is the consequence if the electrically controlled poppet valve remains energized for an extended period during plunger motion?

Insufficient fuel will be delivered to the injector Signup and view all the answers

What is the purpose of maintaining fuel temperature at about 100°F (37.74°C)?

To aid in injection control Signup and view all the answers

What type of fuel filtration is provided before the fuel reaches the pump?

Primary fuel filter assembly Signup and view all the answers

What is the maximum capacity of the pump described in the content?

6.5 gallons per minute Signup and view all the answers

What does the inverter do in the described system?

Handles conversion from 74VDC to AC Signup and view all the answers

Which pressure is associated with the primary fuel filter assembly?

30 psi (206.85 kPa) Signup and view all the answers

What is the result of forcing fuel through a pre-heater?

It aids in ensuring consistent engine performance Signup and view all the answers

Which of the following statements is true about the fuel pre-heater?

It is thermostatically controlled Signup and view all the answers

What is the design comparison made about the pump in the content?

It is identical to the turbo lube pump Signup and view all the answers

What happens to the fuel after it is forced from the pump?

It is passed through a primary filter assembly Signup and view all the answers

What is the primary role of the thermostatic control in the fuel pre-heater?

To maintain the desired fuel temperature Signup and view all the answers

What occurs when the plunger moves down in the injector system?

The lower port closes, allowing fuel only to escape through the helix. Signup and view all the answers

What is the primary role of the recess called a helix in the injector plunger?

To direct fuel flow from the upper port. Signup and view all the answers

At what position is the injector plunger noted to be at the start of the cycle?

Top of its stroke. Signup and view all the answers

What happens to fuel when both ports are closed during the injector operation?

Fuel pressure stabilizes with no flow. Signup and view all the answers

Which component is responsible for initiating the downward movement of the plunger?

The rocker arm. Signup and view all the answers

What is indicated when the plunger has moved down sufficiently to close both ports?

A transition to a fuel injection cycle. Signup and view all the answers

What causes the fuel to escape back through the drilled passage and helix?

The blocking of the lower port by the plunger. Signup and view all the answers

What is the state of fuel flow when the injector plunger is at the 'half load' position?

Fuel flow is halted completely. Signup and view all the answers

What happens after the plunger has moved down far enough in the injector operation?

Both ports close to prevent further fuel intake. Signup and view all the answers

What is the overall effect of one complete downward stroke of the injector plunger?

It creates effective fuel injection into the cylinder. Signup and view all the answers

Study Notes

Fuel System Introduction

The fuel system supplies fuel to the diesel engine in the correct amount and at the right time.
Fuel must be supplied, filtered, pressurized, metered, and injected.
The system is divided into supply and delivery sides.

Supply Side

The supply side includes the fuel tank, fuel pump, filters, and piping.
Fuel is drawn from the tank through a suction strainer.
The strainer removes large debris to protect the pump from damage.
The suction strainer should be cleaned or replaced regularly.
Condensate should be drained from the fuel tank frequently, especially during high humidity.
The strainer is a screen type element.

Delivery Side

The delivery side includes the fuel injectors, the layshaft mechanism, and the control device or governor.
The fuel must be delivered to the injection mechanism at the correct pressure.
The rate of fuel injection must be controlled.
The fuel must be broken into fine particles and distributed in the combustion chamber.
The fuel is delivered to the injectors via fuel manifolds. Injection timing and fuel metering are simultaneously controlled.
Jumper lines are used to connect each injector to the fuel rail.
Fuel returns from the injectors to the return fuel check valve, and then to the tank.
The return fuel sight glass gives a visual indication of system condition.
Air bubbles indicate filter problems, suction leaks, or faulty injectors.

Unit Injector System

A unit injector system combines the pump and nozzle into a single unit.
This eliminates the high-pressure fuel lines, enabling extremely high injection pressures (up to 30,000 psi).
Each cylinder head has a unit injector, controlled by a rocker arm from the camshaft.
It includes a plunger, delivery valve, and nozzle to create the desired spray pattern.
The fuel flows through a complex system of internal components including a helix, a drilled passage through the plunger, upper, and lower ports.

Injector Operation

The unit injector takes fuel from the supply, meters, times, pressurizes, and atomizes it.
The plunger movement controls injection timing, duration, and the amount of fuel.
When the plunger moves down, fuel is trapped and pressurized.
The poppet valve opens to allow fuel to enter the combustion chamber.
As the plunger continues downward, injection stops when the lower port opens fully.

Fuel System Troubleshooting

Verify fuel is present in the tank to avoid incorrect conclusions.
Check fuel pressure, especially for low or no pressure issues.
Visually inspect all piping for leaks and restrictions.
Check suction strainer, primary and secondary filters for obstructions.
Check for internal injector leaks by listening for "clunk" sounds or fuel in the engine's lubricating oil.
Check for faulty or leaking injectors to determine if replaced injectors are required.

Fuel System Maintenance

Daily or trip checks of fuel levels are essential for adequate fuel supply and to prevent filter failure.
90-day inspections include cleaning and replacing primary fuel filters, cleaning the tank, and changing paper elements. Secondary filters also require renewal.
180-day inspections include checking the suction strainer for contaminants.
Three-year inspections involve replacing all injectors.
Six-year inspections include renewing the pump and motor to optimize performance.
Primary fuel filters are 13 micron elements, increased in size from older systems.
Secondary filters are 5 micron spin-on units.
Fuel manifolds are larger and use braided hoses instead of rigid tubing.
Bypass valve pressure has increased to 120 psi from 60 psi.
Control units for injection systems are mounted on cold plates.

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Description

This quiz covers key concepts related to injector testing and electronic fuel control systems in engines. Participants will learn about the procedures and tools required for conducting injector pressure tests, as well as the impact of various factors on fuel injection performance. Dive into the mechanics of how fuel systems operate for optimal engine efficiency.