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Mechanical Injection > Advanced Mechanical Fuel Injection Systems > Flashcards

Advanced Mechanical Fuel Injection Systems Flashcards

0
Q

Port and helix barrel

A

Is retained in a fixed position in pump housing. It contains ports that allow fuel to enter and leave the pumping element.

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1
Q

What are the two basic components of the port and helix pumping element?

A

Plunger and Barrel

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2
Q

Port and helix plunger

A

Has a constant up and down stroke. Plunger rotates is barrel, this changes metering. The helix is an angular groove machined in the outside, it determines the effective stroke

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3
Q

What are the 4 main stages of a plunger stroke?

A

Bottom of stroke - Cavity fills
Port closing - Plunger is moving up BOI
Delivery - Delivery valve is opened
Port opening - EOI

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4
Q

The vertical groove in the plunger is what position?

A

The fuel shut off position

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5
Q

Fuel injection tubing

A

High pressure seamless steel tubing. all tubes off of a pump will be the same length

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6
Q

The delivery valve serves as a check valve to?

A

Retain a head of pressure

Assist in dropping fuel injection line pressure at EOI to positively close the injection nozzle

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7
Q

Fuel control rack

A

Connects the control and gear to the throttle and governor assembly. in multi-plunger pump all sleeves are indexed to a common rack.

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8
Q

How does the control sleeve interact with plunger?

A

Control sleeve is slotted and engages with plunger to control rotation during pump operation

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9
Q

What are 2 common names for a exhaust smoke control?

A

Smoke limiting control

Air fuel ratio control

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10
Q

What is central purpose of a exhaust smoke control?

A

limit fuel control rack travel until a sufficient amount of boost pressure is present

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11
Q

What is timing?

A

The procedure of synchronizing the injection pump to the engine

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12
Q

Prior to installing a port and helix injection pump you need to?

A

Rotate pump camshaft in normal direction of rotation until the timing mark on the injection pump drive hub lines up with the fixed timing mark on the pump housing

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13
Q

When setting for pump timing the engine should be rotated in what direction? why?

A

Normal engine rotation. To prevent gear train lash from affecting timing accuracy

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14
Q

What two companies manufacture opposed plunger pumps?

A

Stanadyne (Roosa Master)

Lucas (CAV)

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15
Q

Opposed plunger pumps are also called?

A

Rotary or Distributor fuel injection pumps

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16
Q

How is an opposed plunger pump driven?

A

A shaft that couples to the engine gear train

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17
Q

Opposed plunger transfer pump

A

a vane type pump is driven by the pump rotor. As rotor speed increases, volume and pressure increases proportionately.

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18
Q

Cam rings will have how many lobes?

A

Usually the same number as the number of engine cylinders

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19
Q

The plungers are retained by what?

A

Roller shoes that are held inside of the cam ring

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20
Q

What is the purpose of the metering valve?

A

Control the amount of fuel delivered to each fuel injector.

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21
Q

How is the metering valve controlled?

A

It is connected to the governor and throttle assembly

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22
Q

What supplies fuel to the metering valve?

A

The transfer pump

23
Q

How is timing advanced in a opposed plunger pump?

A

As engine speed increases, increased transfer pump pressure acts on the piston and moves the cam ring int he opposite direction of normal fuel pump rotation to advance the timing

24
Q

What method should be used to time a opposed plunger pump?

A

Static timing

25
Q

What is the last step in timing a Lucas pump?

A

Line up the mark on the pump with the timing mark on the engine timing cover

26
Q

After installation a Stanadyne pump can be static timed by?

A

lining up the marks in the timing window on the side of the pump housing

27
Q

The maximum fuel delivery of an opposed plunger pump is set by?

A

Adjusting the roller to roller dimension of the pumping element

28
Q

The pumping elements of an opposed plunger pump include?

A

Rotor, Hydraulic head, Shoes & rollers, Plungers and Cam ring

29
Q

Spraying cold water on an injection pump could cause it to?

A

Seize

30
Q

A fuel injector consists of what 3 major components?

A

A nozzle holder
A nozzle assembly
A retaining nut

31
Q

Nozzle holder

A

Sometimes referred to as the fuel injector body, positions the fuel injector assembly in the head. A spring in the fuel injector controls the nozzle opening pressure

32
Q

What are the 2 major components of the nozzle assembly?

A

Nozzle body

Needle valve

33
Q

What are the two basic designs of hydraulically operated fuel injection nozzles?

A

Multi-hole

Pintle

34
Q

Multi-hole nozzles

A

Are the most common, used in direct injection engines. Tip has a series of small holes that are precisely sized and angled to produce a specific spray pattern

35
Q

Opening pressures for multi-hole nozzles range from?

A

2500 - 5000 PSI

36
Q

Pencil fuel injectors

A

Are a multi-hole design, but the nozzle body and nozzle are one piece assembly. opening pressures range from 2500 - 4000 PSI

37
Q

Where are pintle nozzles used?

A

Indirect injection engines with pre-combustion chambers

38
Q

Pintle nozzles

A

Produce a hollow, cone shaped spray pattern as fuel sprays out of single hole. Pressures 1400-2500 PSI

39
Q

What is nozzle dribble?

A

When the fuel continues to drip out of nozzle tip after injection has ended

40
Q

What are the 3 major factor that effect injector nozzle operation?

A

Dirt, Heat, Water

41
Q

What tools should be used to remove injector lines

A

2 flare nut wrenches

42
Q

During engine operation, the governor does what?

A

Senses engine RPM
Reacts to RPM changes
Controls the fuel system to adjust metering as required

43
Q

When there is no changes in engine load or speed the governor is in what state?

A

Steady state

44
Q

In order to accomplish the required functions, engine governors have a?

A 
Throttle mechanism (operator input)
Speed sensing mechanism
Connection between the speed sensing device and the fuel control linkage
45
Q

Low idle speed

A

Lowest no load speed that the engine will run without operator input

46
Q

High idle speed

A

The highest governor controlled no load speed of an engine

47
Q

Rated engine speed

A

The maximum full load speed of the engine and is usually the speed at which engine develops is max power

48
Q

Peak torque speed

A

Where max torque is developed

49
Q

Speed droop

A

Is the change in engine RPM from a no load to full load condition, generally expressed as a percentage of the rated speed.

50
Q

Isochronous governing

A

Is a condition in which a zero speed droop condition occurs as engine loads change. With a isochronous governor, the no-load speed is the same as full-load speed

51
Q

What are the 3 types of mechanical governors?

A

Limiting speed
Variable speed
Constant speed

52
Q

Where would you commonly find timing mark for positioning the engine?

A

The flywheel and vibration damper

53
Q

What is the purpose of the retraction step?

A

To assist in the delivery valve(s) in creating a quick EOI, it is machined as part of the internal cam ring lobe design

54
Q

The timing advance of an opposed plunger fuel pump is sensitive to changes in engine speed through change in?

A

transfer pressure in the injection pump

Mechanical Injection (7 decks)

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