Fuel System Service

Question 1

How are filters rated?

Answer 1

According to their ability to stop particles of a certain size

Question 2

What are the 4 basic types of fuel filters?

Answer 2

Screen or Strainer
Surface
Depth
Edge

Question 3

Screen and Strainers

Answer 3

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

Question 4

Why are spin on filters the most common filter design?

Answer 4

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

Question 5

What are the common materials used in depth type filters

Answer 5

Cotton yard
Cloth
Wood fibre
Porous metal

Question 6

What are the common filter classifications?

Answer 6

Primary
Secondary
Final Stage

Question 7

What size particle will each type of filter remove?

Answer 7

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

Question 8

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

Answer 8

By-pass valve

Question 9

What is the function of a transfer pump?

Answer 9

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

Question 10

What are the 5 basic types of fuel transfer pumps?

Answer 10

Diaphragm 
Plunger
Hand primer
Gear
Vane or Blade

Question 11

Diaphragm type transfer pump

Answer 11

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.

Question 12

Where are plunger type pumps most commonly used?

Answer 12

On a multi-plunger injection pump

Question 13

Plunger type pumps

Answer 13

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

Question 14

Gear type pumps

Answer 14

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.

Question 15

Vane type pumps

Answer 15

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

Question 16

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

Answer 16

Fuel level

Question 17

High inlet restriction can be the result of?

Answer 17

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

Question 18

To check fuel pressure you should?

Answer 18

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

Question 19

Low fuel pressure could be the result of?

Answer 19

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

Question 20

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

Answer 20

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

Question 21

The correct amount of fuel is important to ensure?

Answer 21

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

Question 22

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

Answer 22

Low fuel pressure can be an indication of reduced fuel flow

Question 23

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

Answer 23

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

Question 24

Air in the fuel system can be the result of?

Answer 24

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

Question 25

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

Answer 25

1%

Question 26

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

Answer 26

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

Question 27

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

Answer 27

microns

Question 28

Explain how surface type filters remove particles from the fuel?

Answer 28

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

Question 29

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

Answer 29

Use hand transfer pump | Fill with clean pre-filtered fuel

Question 30

Diaphragm and plunger type fuel pumps are self regulating because?

Answer 30

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

Question 31

What 5 fuel problems could cause hard starting?

Answer 31

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

Question 32

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

Answer 32

The proper training A clean environment The correct tools

Question 33

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

Answer 33

Low volume or pressure

Question 34

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

Answer 34

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

Question 35

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

Answer 35

``` Ends of the vanes Sides of the vanes Rotor slots Inside surface of the liner End plate or cover ```

Question 36

Wear inside of a vane type pump causes?

Answer 36

Internal leakage and reduces pump output

Question 37

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

Answer 37

flow meter

Question 38

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

Answer 38

1 to 3 microns