Heavy Equipment and Truck Systems – Fuel Systems 1 – Lecture Summary &
Practice Questions
If a diesel engine was running rough due to air in fuel, what would be the most likely cause?
a crack in the pick-up tube near the top of the tank
a loose connection at the outlet of the transfer pump
worn gears in a gear type charge pump
a crack in the pressure regulator fitting found at the return - correct answer ✔✔a crack in the
pick-up tube near the top of the tank
A leak in the return line running from the cylinder head to the tank on a diesel engine would:
have excessive fuel running on the ground only
run rough at idle
emit black smoke under load
all of the above - correct answer ✔✔have excessive fuel running on the ground only
If a pin hole in a filter is the cause of air entering a fuel system, what filter would it be?
primary / water separator
secondary
both A and B - correct answer ✔✔primary / water separator
If every morning a diesel engine is hard to start but runs fine once started, what is the most
likely cause for this condition?
fuel tank is empty
fuel is too hot
air in fuel
faulty one way check valve - correct answer ✔✔faulty one way check valve
, If a diesel engine was to suddenly quit running and when the fuel tank cap was removed a rush
of air into the tank was heard, what would be the most likely cause?
a plugged fuel filter
a defective pressure regulator
a plugged fuel tank vent
a weak fuel pump - correct answer ✔✔a plugged fuel tank vent
Which of the following is found in diesel fuel that produces SO2?
nitrogen
oxygen
hydro carbon
sulfer - correct answer ✔✔sulfer
Which of the following is a function of the fuel tank?
allows dirt to settle in bottom
allows air to mix with fuel
stores fuel vapors only
heats the fuel for better atomization - correct answer ✔✔allows dirt to settle in bottom
What type of injector has a pump built into that injector?
hydraulic
unit injector
nozzle
pintle injector - correct answer ✔✔unit injector
Practice Questions
If a diesel engine was running rough due to air in fuel, what would be the most likely cause?
a crack in the pick-up tube near the top of the tank
a loose connection at the outlet of the transfer pump
worn gears in a gear type charge pump
a crack in the pressure regulator fitting found at the return - correct answer ✔✔a crack in the
pick-up tube near the top of the tank
A leak in the return line running from the cylinder head to the tank on a diesel engine would:
have excessive fuel running on the ground only
run rough at idle
emit black smoke under load
all of the above - correct answer ✔✔have excessive fuel running on the ground only
If a pin hole in a filter is the cause of air entering a fuel system, what filter would it be?
primary / water separator
secondary
both A and B - correct answer ✔✔primary / water separator
If every morning a diesel engine is hard to start but runs fine once started, what is the most
likely cause for this condition?
fuel tank is empty
fuel is too hot
air in fuel
faulty one way check valve - correct answer ✔✔faulty one way check valve
, If a diesel engine was to suddenly quit running and when the fuel tank cap was removed a rush
of air into the tank was heard, what would be the most likely cause?
a plugged fuel filter
a defective pressure regulator
a plugged fuel tank vent
a weak fuel pump - correct answer ✔✔a plugged fuel tank vent
Which of the following is found in diesel fuel that produces SO2?
nitrogen
oxygen
hydro carbon
sulfer - correct answer ✔✔sulfer
Which of the following is a function of the fuel tank?
allows dirt to settle in bottom
allows air to mix with fuel
stores fuel vapors only
heats the fuel for better atomization - correct answer ✔✔allows dirt to settle in bottom
What type of injector has a pump built into that injector?
hydraulic
unit injector
nozzle
pintle injector - correct answer ✔✔unit injector
