ABYC DIESEL EXAM PRACTICE
QUESTIONS LATEST 2024|2025
UPDATES
when changing the primary fuel filter on the a Diesel engine, a technician discovers
black stringy material in the filter. This condition is most likely caused by - Answer-fuel
contamination
which one of the following types of fuel indicators are permitted by ABYC standard H-33
- Answer-Dipstick
electronic sender
sight gauge
when replacing the secondary fuel filter, the preferred procedure is to - Answer-Use the
on-engine bleeding system at the secondary filter
a technician determines a history of excessive water contaminated fuel. the operator
has been using a variety of fuel sources. the LEAST likely cause is - Answer-the fuel
source is contaminated
What would happen if a high pressure fuel line was replaced with a line longer than the
original line - Answer-the timing would change because of the extension of the line
length
a customer complains of white smoke only when the engine is cold. Technician A says
that this could be caused by a faulty pre-heat device. Technician B says that the white
smoke is caused by partially vaporized fuel. Who is right? - Answer-Both technicians
are correct
excessive black exhaust smoke is an indication of - Answer-excessive load or over
fueling
A customer complains the engine idle is rough. Technician A says air in the fuel system
may be the cause. Technician B says the fuel shut-off solenoid is not operating. Who is
correct? - Answer-Technician A
when testing an injector nozzle, the technician should test for - Answer-Spray pattern
valve opening pressure
leakage
, the amount of fuel delivered by each pumping element to the nozzles on pumps is
controlled by the - Answer-effective stroke of the plunger
during a sea trial with mechanical governor engines too find the port engine will not
come up to full load, your notes show the high idle on the port engine was 300 rpm
below specs. the most likely answer is - Answer-throttle linkage adjustment
you are troubleshooting a sudden oil leak on a low hour mechanical engine, the
customer complains that the dipstick is being pushed out of the block and oil is leaking
from the front crankshaft seal. the most likely answer is - Answer-plugged crankcase
breather
after severely overheating his engine and making the required repairs the customer
complains of excessive coolant usage. your test show that during normal running the
engine does NOT overheat, but coolant is pushing out through the over flow tube of the
expansion tank. what would most likely NOT be the cause? - Answer-raw water pump
impeller
The customer complains that both engines of his boat shut down unexpectedly while he
was returning to port and they still will not restart. one possible explanation is - Answer-
there is a problem with the fire extinguishing system that sent a shutdown signal
the owner says his engine (electronic controlled) will bot start. He mentioned he has
added a power connection for his portable GPS at the dash since he last used the boat.
Where might you begin to find the problem? - Answer-His choice of connection points
for power and ground of his GPS
The owner complains his engine turns over slower than usual when he attempts to start
it. the battery has tested perfectly and you suspect a battery cable problem, but not all
the cabling is accessible. you decide to do a voltage drop on the positive cable run. -
Answer-You connect your voltmeter positive lead to the battery positive and the
negative lead to the starter positive and take a reading while cranking the engine
The owner is complaining of low power. On a sea trial under full load you measure
exhaust gas temperature and boost pressure. You explain to the owner you feel he
might have a cylinder not putting out full power because: - Answer-The boost and the
temperature are both below specification
the owner is complaining of low top end speed. On a sea trial under full load you
measure exhaust has temperature and boost pressure. you explain to the owner you
feel the engine is overloaded based on - Answer-The boost is lower than specification
and the temperature is above specification
The customer replaced a completely failed raw water pump impeller and performed an
extensive cleaning of impeller debris. He now complains his engine has developed
several exhaust leaks at the turbocharger and is low on power. What caused this? -
QUESTIONS LATEST 2024|2025
UPDATES
when changing the primary fuel filter on the a Diesel engine, a technician discovers
black stringy material in the filter. This condition is most likely caused by - Answer-fuel
contamination
which one of the following types of fuel indicators are permitted by ABYC standard H-33
- Answer-Dipstick
electronic sender
sight gauge
when replacing the secondary fuel filter, the preferred procedure is to - Answer-Use the
on-engine bleeding system at the secondary filter
a technician determines a history of excessive water contaminated fuel. the operator
has been using a variety of fuel sources. the LEAST likely cause is - Answer-the fuel
source is contaminated
What would happen if a high pressure fuel line was replaced with a line longer than the
original line - Answer-the timing would change because of the extension of the line
length
a customer complains of white smoke only when the engine is cold. Technician A says
that this could be caused by a faulty pre-heat device. Technician B says that the white
smoke is caused by partially vaporized fuel. Who is right? - Answer-Both technicians
are correct
excessive black exhaust smoke is an indication of - Answer-excessive load or over
fueling
A customer complains the engine idle is rough. Technician A says air in the fuel system
may be the cause. Technician B says the fuel shut-off solenoid is not operating. Who is
correct? - Answer-Technician A
when testing an injector nozzle, the technician should test for - Answer-Spray pattern
valve opening pressure
leakage
, the amount of fuel delivered by each pumping element to the nozzles on pumps is
controlled by the - Answer-effective stroke of the plunger
during a sea trial with mechanical governor engines too find the port engine will not
come up to full load, your notes show the high idle on the port engine was 300 rpm
below specs. the most likely answer is - Answer-throttle linkage adjustment
you are troubleshooting a sudden oil leak on a low hour mechanical engine, the
customer complains that the dipstick is being pushed out of the block and oil is leaking
from the front crankshaft seal. the most likely answer is - Answer-plugged crankcase
breather
after severely overheating his engine and making the required repairs the customer
complains of excessive coolant usage. your test show that during normal running the
engine does NOT overheat, but coolant is pushing out through the over flow tube of the
expansion tank. what would most likely NOT be the cause? - Answer-raw water pump
impeller
The customer complains that both engines of his boat shut down unexpectedly while he
was returning to port and they still will not restart. one possible explanation is - Answer-
there is a problem with the fire extinguishing system that sent a shutdown signal
the owner says his engine (electronic controlled) will bot start. He mentioned he has
added a power connection for his portable GPS at the dash since he last used the boat.
Where might you begin to find the problem? - Answer-His choice of connection points
for power and ground of his GPS
The owner complains his engine turns over slower than usual when he attempts to start
it. the battery has tested perfectly and you suspect a battery cable problem, but not all
the cabling is accessible. you decide to do a voltage drop on the positive cable run. -
Answer-You connect your voltmeter positive lead to the battery positive and the
negative lead to the starter positive and take a reading while cranking the engine
The owner is complaining of low power. On a sea trial under full load you measure
exhaust gas temperature and boost pressure. You explain to the owner you feel he
might have a cylinder not putting out full power because: - Answer-The boost and the
temperature are both below specification
the owner is complaining of low top end speed. On a sea trial under full load you
measure exhaust has temperature and boost pressure. you explain to the owner you
feel the engine is overloaded based on - Answer-The boost is lower than specification
and the temperature is above specification
The customer replaced a completely failed raw water pump impeller and performed an
extensive cleaning of impeller debris. He now complains his engine has developed
several exhaust leaks at the turbocharger and is low on power. What caused this? -
