Exam 28: Gasoline, Diesel, and Other Fuels

Technician A says large, low-speed industrial diesels require a high-quality and highly volatile fuel because they cannot tolerate excessive carbon deposits that result from low-volatile fuels. Technician B says the small, high-speed diesel engines found in passenger cars are relatively unaffected by carbon deposits and can run on low-quality fuel. Who is correct?

What is the difference between a full hybrid and an assist hybrid?

What are the four main components of a typical hybrid system?

Most diesel fuel currently available at the pump has a cetane rating of ______.

Technician A says a lean mixture burns faster than a rich mixture. Technician B says advanced ignition timing induces knock. Who is correct?

Fuel additives are being discussed. Technician A says adding oxygenates to gasoline increases fuel economy. Technician B says adding 10 percent ethanol to gasoline may boost the octane rating 2.5 to 3 points. Who is correct?

What is the major disadvantage of current all electric vehicles?

While discussing common rail fuel injection systems: Technician A says the individual injectors are activated by the high pressure present in the fuel rail. Technician B says some late-model CR systems have an intensifier in the injector that allows for an increase in fuel pressure. Who is correct?

Older engines with nonhardened valve seats may need a _____ substitute added to gasoline or ethanol blends to prevent premature valve seat wear.

Which of the following is NOT an advantage of biodiesel fuel?

Technician A says increasing the Reid vapor pressure [RVP] will help the engine start easier in cold weather. Technician B says increasing the RVP will increase the possibility of fuel boiling [vapor lock] in summer driving. Who is correct?

LP-gas is commonly called ____________________.

What equipment is needed to safely test the high-voltage components of the hybrid vehicle electrical system?

Pump gasoline may safely contain up to 10 percent alcohol.

Oxygenated fuels tend to have higher CO emissions.

Technician A says there is less heat energy in high-octane gasoline and, therefore, less power is generated during combustion. Technician B says using a higher-octane gasoline than required will not produce more power unless the engine has a knock sensor that allows the system to adjust ignition timing to take advantage of the higher octane. Who is correct?

All the following are factors that cause knock EXCEPT:

Vapor lock is caused by fuel that does not vaporize easily in hot weather.

Which of the following is considered natural gas?