203d - Fuel System Service Flashcards
A micron is ______ of a meter?
1 millionth of a meter
0.000001m
203d pg. 2
How wide is a human hair in microns?
70 microns
203d pg. 2
What is the smallest particle visible to the human eye?
40 microns
203d pg. 2
In injection pumps and injectors, precision machined parts are fitted with how small of clearances?
1-3 microns
203d pg. 2
What size of particles are the most damaging to fuel injection equipment?
5-20 microns
203d pg. 2
What are four basic types of fuel filters?
- Screen / strainer
- Surface
- Depth
- Edge
203d pg. 2
Where are screen type filters typically used?
Fuel tank inlet
203d pg. 3
What type of filter element do surface type filters use?
Pleated paper
203d pg. 4
What are two disadvantages of depth type fuel filters?
- Less efficient
- More expensive
203d pg. 5
How do edge type fuel filters work?
Trap particles as the fuel flows over ledges.
No micron rating. Not a positive method of filtration.
203d pg. 6
What are three common filter classifications?
- Primary (25 micron)
- Secondary (5 micron)
- Final stage
203d pg. 6
What are the general properties of a primary fuel filter?
- 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
What are the general properties of a secondary filter?
- Typically 5 microns
- On the outlet side of transfer pump
- Under pressure
203d pg. 6
What are the general properties of a final stage fuel filter?
- Typically 1 micron
- Located just before the injection pump
- Under pressure
203d pg. 7
Oil filters incorporate a bypass valve as a safety feature if they become plugged.
Do fuel filters also contain a bypass valve?
No. All fuel must be filtered.
203d pg. 7 & 10