203d - Fuel System Service Flashcards

1
Q

A micron is ______ of a meter?

A

1 millionth of a meter
0.000001m

203d pg. 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How wide is a human hair in microns?

A

70 microns

203d pg. 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the smallest particle visible to the human eye?

A

40 microns

203d pg. 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

In injection pumps and injectors, precision machined parts are fitted with how small of clearances?

A

1-3 microns

203d pg. 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What size of particles are the most damaging to fuel injection equipment?

A

5-20 microns

203d pg. 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are four basic types of fuel filters?

A
  • Screen / strainer
  • Surface
  • Depth
  • Edge

203d pg. 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where are screen type filters typically used?

A

Fuel tank inlet

203d pg. 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of filter element do surface type filters use?

A

Pleated paper

203d pg. 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are two disadvantages of depth type fuel filters?

A
  • Less efficient
  • More expensive

203d pg. 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do edge type fuel filters work?

A

Trap particles as the fuel flows over ledges.

No micron rating. Not a positive method of filtration.

203d pg. 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are three common filter classifications?

A
  • Primary (25 micron)
  • Secondary (5 micron)
  • Final stage

203d pg. 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the general properties of a primary fuel filter?

A
  • Typically 25 microns
  • First filter after fuel tank
  • Intended to protect the transfer pump
  • Usually under a vacuum
  • May be combined with a water separator

203d pg. 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the general properties of a secondary filter?

A
  • Typically 5 microns
  • On the outlet side of transfer pump
  • Under pressure

203d pg. 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the general properties of a final stage fuel filter?

A
  • Typically 1 micron
  • Located just before the injection pump
  • Under pressure

203d pg. 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Oil filters incorporate a bypass valve as a safety feature if they become plugged.

Do fuel filters also contain a bypass valve?

A

No. All fuel must be filtered.

203d pg. 7 & 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When is the greatest chance for fuel system contamination to occur?

A

During refuelling or fuel filter maintenance.

203d pg. 7

17
Q

Is it better to pre-fill fuel filters or use the built-in hand priming pump?

A

Use the hand priming pump. Less chance of contamination.

203d pg. 8

18
Q

What would result from air entering the fuel system?

A
  • Reduced volume of injected fuel
  • Delayed injection timing
  • Rough running engine

203d pg. 10

19
Q

What are five basic types of fuel transfer pumps?

A
  • Diaphragm
  • Plunger
  • Hand primer
  • Gear
  • Vane/blade

203d pg. 11

20
Q

What causes a diaphragm pump to enter a neutral pumping state?

A

When the pressure on the outlet side equals the diaphragm spring force.

203d pg. 12

21
Q

How are diaphragm transfer pumps self regulating?

A

Diaphragm spring tension controls max pressure.

203d pg. 12

22
Q

What pressures do diaphragm fuel transfer pumps operate at?

A
  • 3-5 psi operating pressure
  • Max 10 psi

203d pg. 12

23
Q

Where are plunger type fuel transfer pumps typically mounted?

A

On the injection pump housing and driven by an eccentric on the pump camshaft.

203d pg. 13

24
Q

Fuel flow through a plunger type fuel transfer pump is controlled by a set of:

A

Check valves

203d pg. 14

25
Q

What pressures do plunger type fuel transfer pumps operate at?

A

Maximum 25-30psi
Operating pressure is set by the injection pump overflow valve.

203d pg. 15

26
Q

On a plunger type transfer pump, why should the hand priming pump shaft be seated and locked in place when not in use?

A
  • Keep air, dirt, and water from entering pump
  • Prevent fuel leakage

203d pg. 16

27
Q

Is a gear type transfer pump a positive or non-positive displacement pump?

A

Positive displacement. Must have a relief valve to set maximum pressure.

203d pg. 17

28
Q

What range should be selected for a pressure gauge?

A

A range no greater than twice the pressure being measured.

203d pg. 22

29
Q

What sets the inlet supply fuel pressure to a port & helix injection pump?

A

Overflow valve

203d pg. 22

30
Q

Where should a vacuum gauge be installed when checking for fuel inlet restriction?

A

As close as possible to the transfer pump inlet.

203d pg. 23

31
Q

What are typical maximum inlet fuel restriction amounts for clean and dirty fuel filters?

A

Clean filter: 3 inHg
Dirty filter: 6 inHg

203d pg. 23

32
Q

Where would a pressure gauge be connected to measure fuel supply pressure to an injection pump?

A

On the outlet side of the transfer pump after the secondary filter.

203d pg. 24

33
Q

What could cause low fuel pressure at the inlet of an injection pump?

A
  • High transfer pump inlet restriction
  • Restricted fuel lines
  • Plugged fuel filters
  • Worn transfer pump
  • Relief valve stuck open

203d pg. 24

34
Q

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

A
  • Submerge the return line in a bucket and watch for bubbles
  • Instal a sight glass in the fuel line before the transfer pump inlet

203d pg. 28

35
Q

For every 10 degrees Fahrenheit above 100 degrees, engine power decrease by:

A

1%

203d pg. 28

36
Q

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

A
  • Use the hand primer/transfer pump
  • Use pre-filtered fuel

203D

37
Q
A