NAPA Fuel Systems & Fuel Delivery 3

Question 1

During a fuel pressure test, what does rapid pressure drop immediately after the pump shuts off indicate?

Accepted Answer

A faulty fuel pressure regulator or leaking fuel injectors

Answer

Insufficient fuel level in the tank

Answer

A weak or failing fuel pump

Answer

A severely clogged fuel filter

Question 2

What instrument is used to measure fuel pump volume output during a flow test?

Accepted Answer

Graduated cylinder timed flow test

Answer

Vacuum gauge

Answer

Compression tester

Answer

Multimeter set to DC amps

Question 3

Which condition is most likely to cause a persistently rich air-fuel mixture?

Accepted Answer

A leaking fuel injector that drips when commanded closed

Answer

A large vacuum leak at the intake manifold

Answer

A MAP sensor reading higher vacuum than actual

Answer

A partially clogged fuel filter

Question 4

What is the correct method for testing a fuel injector's electrical coil?

Accepted Answer

Measure resistance across the injector terminals with an ohmmeter

Answer

Apply battery voltage and observe spray with a test light

Answer

Use a vacuum gauge connected to the injector port

Answer

Measure fuel pressure drop across the injector with a gauge

Question 5

What is the most common cause of in-tank electric fuel pump failure?

Accepted Answer

Habitually running the fuel tank at very low levels, reducing pump cooling

Answer

Consistently using premium fuel instead of regular

Answer

Overfilling the fuel tank past the full mark

Answer

Using ethanol-blended fuel on a non-flex-fuel vehicle

Question 6

What does evaluating an injector's spray pattern reveal about its condition?

Accepted Answer

Whether the injector atomizes fuel into a proper mist or streams and dribbles

Answer

The injector coil resistance value

Answer

The injector's electrical pulse width

Answer

The fuel pressure drop across the injector tip

Question 7

What is the purpose of a fuel system check valve (one-way valve)?

Accepted Answer

To maintain residual pressure in the fuel lines after the pump shuts off

Answer

To limit maximum fuel rail pressure under load

Answer

To prevent fuel vapors from entering the EVAP canister

Answer

To filter large debris particles before the inline fuel filter