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Mechanical Injection > Fuel System Service > Flashcards

Fuel System Service Flashcards

1
Q

How are filters rated?

A

According to their ability to stop particles of a certain size

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2
Q

What are the 4 basic types of fuel filters?

A

Screen or Strainer
Surface
Depth
Edge

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3
Q

Screen and Strainers

A

commonly used in the inlet of fuel tanks and the outlet lines of off-road equipment. Are a surface type filters

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4
Q

Why are spin on filters the most common filter design?

A

Simplistic design and relatively low cost
Ease of surface
Less chance of dirt entering the fuel system during service

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5
Q

What are the common materials used in depth type filters

A

Cotton yard
Cloth
Wood fibre
Porous metal

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6
Q

What are the common filter classifications?

A

Primary
Secondary
Final Stage

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7
Q

What size particle will each type of filter remove?

A

Primary - larger than 25 microns
Secondary - larger than 5 microns
Final stage - Down to 1 micron

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8
Q

Fuel filters differ from most oil filters in that they do not have?

A

By-pass valve

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9
Q

What is the function of a transfer pump?

A

Move fuel from the tank through the filter to the high pressure pumping mechanism. Pumps create low pressure.

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10
Q

What are the 5 basic types of fuel transfer pumps?

A 
Diaphragm 
Plunger
Hand primer
Gear
Vane or Blade
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11
Q

Diaphragm type transfer pump

A

May be operated off the engine or injection pump. Will work with cam turning in either direction. Are self regulating. Output usually around 10 PSI. Produce a pulsating output. May include a sediment and/or water separator.

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12
Q

Where are plunger type pumps most commonly used?

A

On a multi-plunger injection pump

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13
Q

Plunger type pumps

A

Usually operated by a cam or eccentric on injection pump cam. Will work will drive in either direction. Self regulating. 25-30 PSI. Produce a pulsating output. May have a hand primer

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14
Q

Gear type pumps

A

Consists of two perfectly meshed gears turning in an enclosed housing. Spur gears are most commonly used. Have a specific direction of rotation. Must have a pressure relief.

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15
Q

Vane type pumps

A

Commonly used in single or opposed plunger distributor pumps as an integral transfer pump. Will produce a high volume for size

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16
Q

What is first that should be checked when diagnosing a fuel system issue?

A

Fuel level

17
Q

High inlet restriction can be the result of?

A

A plugged tank vent
Restricted fuel lines
A plugged fuel filter before the pump

18
Q

To check fuel pressure you should?

A

Install a pressure gauge on the outlet side of the transfer pump after the secondary filter

19
Q

Low fuel pressure could be the result of?

A 
High inlet restriction
Restricted fuel lines
a plugged fuel filter 
Worn transfer pump
A relief valve stuck in the open position
20
Q

What are the two basic methods of checking fuel flow volume?

A

Measure the return fuel flow with the engine running at a specific RPM for a specified length of time
Measure the output volume of the fuel pump while the engine is cranking

21
Q

The correct amount of fuel is important to ensure?

A

A sufficient volume of fuel is available for the injection pump or unit injectors to meet engine requirements
Sufficient cooling of injection system components

22
Q

“Since pressure is the result of flow and restriction”; how can this be a indication of fuel issue?

A

Low fuel pressure can be an indication of reduced fuel flow

23
Q

What are the two basic methods for testing for air in the fuel?

A

Submerge the return line in a bucket of fuel and watch for bubbles
Install a sight glass in the fuel line before the transfer pump

24
Q

Air in the fuel system can be the result of?

A

A cracked or broken fuel tank stand pipe
Loose fittings
Cracked fuel lines or fittings
Missing gaskets or O-rings in primary filter

25
Q

For every 10F above 100F of fuel temp, power deceases by?

A

1%

26
Q

Before a fuel pump is removed you must make sure that?

A

The dirt around the pump is removed to help ensure that dirt does not enter the fuel system.

27
Q

Fuel filters are rated according to their ability to stop certain sized particles measured in?

A

microns

28
Q

Explain how surface type filters remove particles from the fuel?

A

They do not allow any particles larger than the holes in the filter medium to pass through

29
Q

To avoid system contamination, what two methods should be used to fill filters during a service?

A

Use hand transfer pump

Fill with clean pre-filtered fuel

30
Q

Diaphragm and plunger type fuel pumps are self regulating because?

A

Diaphragm or plunger spring tension limits the maximum pressure that the pump can develop

31
Q

What 5 fuel problems could cause hard starting?

A 
Low fuel level
Restricted inlet
Cracked or loose inlet pipes
Plugged filter (before pump)
Fuel system draining back to tank after shutdown
32
Q

Sealed fuel injection pumps should not be disassembled unless you have?

A

The proper training
A clean environment
The correct tools

33
Q

A plunger type pump with a weak or broken plunger spring would have?

A

Low volume or pressure

34
Q

What 3 clearances should be checked when inspecting a gear type transfer pump?

A

Gear to gear clearance
Gear to pump body clearance
Gear end clearance

35
Q

What are the 5 areas of a vane type pump that should be checked for wear?

A 
Ends of the vanes 
Sides of the vanes
Rotor slots
Inside surface of the liner
End plate or cover
36
Q

Wear inside of a vane type pump causes?

A

Internal leakage and reduces pump output

37
Q

Some fuel systems must be checked using a special tool called a ________.

A

flow meter

38
Q

Clearance of precision parts in an injection pump should be how many microns?

A

1 to 3 microns

Mechanical Injection (7 decks)

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