203d Flashcards
Contaminants are most likely to enter a fuel system
during refueling
when a new filter is being installed it is essential that
it is filled with clean, filtered fuel before installation
in a plunger type fuel pump, fuel pressure is dependent on the
control spring pressure
what problem may arise when using a gear pump if an obstruction occurs in the fuel line leading to the secondary filter?
the line pressure will continue to rise until the componet damage occurs
a vane pumps ability to produce pressure is due to
an off centre rotor and extending vanes
Engine operational problems include: hard starting, stalling, rough running and low power. only one of the following issues is capable of causing one of these problems:
a. low fuel pressure
b. low fuel levels
c. restricted fuel inlet
d. aerated fuel
b low fuel levels
when performing an injection fuel system SERVICE, the injection pump
must only be service by a qualified personnel
most common problem experienced by hand primers is that
contaminants from the environment get into the pump
visible evidence of contamination making its way into the gear transfer pump is
scoring on the gears or pump body
Fuel filters particales are measured in
microns
Three common filter classifications
primary
secondary
final
Four basic types of filters
s,s,d,e
screen
surface
depth
edge
To avoid system contamination two methods of filling filters are?
hand pump IF equipped
fill filter w. clean fuel
After fuel service is done, a rough engine is a result of?
Air in fuel system
Diaphgram or plunger type fuel pumps are operated by
engine OR fuel injection pump CAMSHAFT
Gear and vane pumps must have 1 to control 2
1 pressure relief valve
2max fuel system pressure
Diaphgram and plunger type fuel pumps are self regulating because
spring tension limits fuel pressure
5 problems that could cause HARD starting
low fuel plugged filter restricted inlet cracked/loose inlet pipes fuel system draining back to tank after shutdown
when performing fuel system testing, guages should be selected with a range that is twice the pressure being measured to:
preotect guage from damage
and
accurate readings
a guage installed between the fuel supply tank and the transfer pump inlet of a running engine would be used to check
inlet restriction
4 problems that could cause LOW fuel system VOLUME
inlet restriction
plugged filter
worn fuel pump
restricted fuel lines
Fuel supply system pressure is measured in
psi or kpa (keyword pressure)
Inlet restriction is measured in
gal/min or l/min (volume)
4 possible causes of air entering system
broken fuel tank stand pipe
loose fittings
cracked/loose fuel lines
missing gasket primary filter
a plunger type pump with a weak or broken plunger spring would have
fuel volume or pressure low symptom
if a gear OR a vane pump had a broken pressure relief valve spring, what effect would this have on the fuel system
low fuel pressure
