mid term fuel systems and performance
"Volatility" is a term used to describe:
A liquid's ability to change to a vapor
Most hybrid electric vehicles are rated under which of the following emission classifications?
AT-PZEV
On a fuel injected engine, what must be done to initiate the PCM's "Clear Flood" mode?
Depress the throttle to at least 80% of WOT, then crank the engine
A complaint of "poor fuel mileage" on a PFI/SFI system with a return line might be caused by all of the following EXCEPT:
Engine idle speed is too slow.
A hydrogen fuel cell vehicle emits which of the following emissions?
Heat and water
On fuel injected vehicles, all of the following methods can be used by the PCM to control idle speed EXCEPT:
The PCM may control an "RPM command signal" to the crankshaft to tell it how fast to run.
A fuel rail does not hold residual pressure when the ignition is turned off. With the engine shut down, the technician then pinches the supply (pressure) hose. Residual pressure now holds. What is the most likely cause of the system's inability to hold residual pressure?
The fuel pump check valve is leaking
"Vaporization" is a term used to describe:
The process where a liquid is changed into a vapor
"Atomization" is a term used to describe:
The process where a liquid is turned into a fine mist of tiny droplets
"Condensation" is a term used to describe:
The process where a vapor is changed into a liquid
Why does a multi‑point fuel injection system with a return line route a manifold vacuum signal to the fuel pressure regulator?
To maintain a constant pressure differential across the fuel injectors during all driving conditions
How should a technician check fuel pressure on the high-pressure side of a GDI engine?
Use a scan tool to check fuel pressure
On a fuel injected system with a return line, the air/fuel ratio is regulated under various driving conditions by:
Varying the injector "on time" or "pulse width"
In order to correct a detonation problem on a vehicle, you should recommend to the customer that he/she use a gasoline that has a:
higher octane
In order to ease cold weather starting, gasoline refiners produce gasoline in the winter months that has a:
higher volatility
If a vehicle has electrical cables that have more than 60 V DC or 30 V AC present, the cable and its connectors is required to be which of the following colors?
orange
Technician A says that if a fuel supply line ruptures during an accident resulting in fuel pressure loss and engine stall, the PCM will shut down the fuel pump. Technician B says that the fuel pump is controlled by the ignition switch only and should always run whenever the ignition switch is in the "run" position. Who is correct?
tech A
Which of the following can be the result if a technician does not follow proper procedure when working on a hybrid vehicle or fuel cell vehicle?
all of the above
On a fuel injection system with a return line, if you applied 10" Hg of vacuum to the fuel pressure regulator with a vacuum pump, approximately how many PSI would the fuel rail pressure decrease by?
5 PSI
Why does the boiling point of a liquid decrease as altitude increases?
Barometric pressure is reduced at higher altitudes.
If a vehicle is towed into the shop because it "will crank but won't start", one of the first tests that a technician should make is to turn the ignition on and listen for the fuel pump to operate for two seconds. If the vehicle is a Ford fuel injected vehicle (model year 1980 - 2009) and he/she does NOT hear the fuel pump operate for two seconds, the next test that he should make is:
Check the Inertia Switch reset button
With the engine running, how is the PCM programmed to pulse the fuel injectors in a Sequential Multi-Point Injection (SMPI/SFI) systems?
Pulse the injectors individually in the engine's firing order
When using a pressure gauge to perform a fuel pressure test on a PFI engine, the technician should:
both A, B A. Connect the pressure gauge to the fuel rail before starting the engine. B. Turn the ignition to "run" & check for fuel leaks after the gauge is connected and before starting the engine.
What advantages does a GDI engine have over a PFI engine?
both A, B A. Increased fuel economy B. Increased power
Why do many modern fuel injection systems no longer use a return line?
both A, B A. To reduce the amount of engine compartment heat that is transferred to the fuel tank B. To reduce the amount of fuel vaporization that takes place in the fuel tank
The "on time" of a fuel injector can be measured with a:
both DMM and DSO
Technician A says that on fuel injection systems, the fuel pump relay carries the high amperage current for the fuel pump. Technician B says that on fuel injection systems with a return line, the fuel pressure regulator is located after the fuel pump and before the fuel injectors. Who is correct?
tech A
Technician A says that you should always use the correct part number when replacing a fuel injector because injectors that look similar may have different flow rates or resistance values. Technician B says that it is proper procedure to use a standard drop light (incandescent light) when replacing a fuel filter underneath a vehicle as long as you are careful. Who is correct?
tech A
Reid Vapor Pressure (RVP) is a unit of measurement used to measure a fuel's:
volatility