30 Questions
What is the main purpose of a fast idle solenoid?
To keep the throttle plates open to avoid dieseling
What is a common problem that the fast idle solenoid helps to address in newer emission-controlled vehicles?
Leaner fuel mixtures and higher operating temperatures
How does the fast idle solenoid work to increase engine speed?
It adjusts the position of the solenoid plunger to hold the throttle plates open
What is the purpose of the throttle return dashpot?
To keep the throttle from closing too quickly when the accelerator pedal is released
Which type of vehicle is the throttle return dashpot commonly used on?
Automatic transmission vehicles
What would happen if a vehicle did not have a throttle return dashpot?
The engine would stall when the accelerator pedal is suddenly released
What component picks up heat from the exhaust without sending any actual exhaust fumes to the choke mechanism?
Heat tube
During warm-up, why does the engine need to run at a faster idle speed?
To prevent flooding
What component prevents the throttle plate from closing when the choke is closed?
Fast idle cam
What is responsible for increasing the engine idle speed during cold engine operation?
Fast idle cam
What device is used to admit air if the engine floods when cold?
Choke un loader
Which mechanism can be either mechanical- or vacuum-operated?
Choke un loader
What happens when the driver presses down on the accelerator?
The off idle ports are exposed to intake manifold vacuum
Which system provides extra fuel when changing from the idle system to the high-speed system?
Acceleration System
What would happen if there was no acceleration system in place?
Engine would stall or hesitate
What is the purpose of the accelerator pump in the acceleration system?
To develop pressure to force fuel into the air horn
Which part of the acceleration system prevents a lean air-fuel mixture?
Pump Check Weight
What action provides enough extra fuel to mix with additional air around the throttle plate?
Throttle plate swings open
What is the purpose of the start spring in the all speed governor?
To hold the control lever against the governor sleeve at low cranking speed
What happens when the adjusting lever is moved to the idle position after starting the engine?
The centrifugal force of the flyweights is counterbalanced by the force of the idle and damper springs, maintaining idle speed
What happens when the adjusting lever is moved to the full load position?
The control spring tension is increased, immediately increasing the effective stroke and engine speed
How does the governor regulate the maximum engine speed?
When engine speed overcomes the predetermined maximum, flyweight force overcomes the tension of the control spring
What is the role of the damper spring in the all speed governor?
To provide stability by counterbalancing the flyweight force at idle speed
What happens to the spill ring when the engine speed exceeds the predetermined maximum?
The spill ring is released, reducing the fuel flow
Where is the hydraulic injection-timing device located on the fuel pump?
At the bottom of the pump, perpendicular to the longitudinal axis
What is the main purpose of the governor in a VE type injection pump?
To control the engine speed during various load conditions
How does the timer piston move as engine rpm rises?
It moves to the left, retarding injection timing
What component converts the lateral motion of the timer piston into rotational motion of the roller ring?
The slide pin
What are the two types of governor used in the VE type injection pump?
All-speed and min./max.
How does the timer spring affect the movement of the timer piston?
It forces the piston to move in the injection "retard" direction
Test your knowledge on the basic operation of a carburetor during off-idle system operation. Learn about how the accelerator, throttle plate, intake manifold vacuum, and fuel mixture work together in the off-idle system.
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