What type of device is characterized by requiring high engine RPM to create a vacuum using exhaust gases?

The correct answer is exhaust primers. These devices take advantage of the vehicle's exhaust gases to create a vacuum that draws fuel into the system, particularly in diesel engines. By operating at high engine RPM, exhaust primers utilize the velocity of the exhaust flow effectively to generate the necessary vacuum. This method is especially useful in ensuring that fuel systems are primed and ready for starting, particularly after maintenance or when the fuel level is low.

Intake boosters, while they serve to enhance the engine's airflow for better performance, do not utilize exhaust gases to create a vacuum. Vacuum pumps are standalone devices that create a vacuum but are not specifically tied to the RPM of the engine or the exhaust system. Fuel primers, on the other hand, are designed primarily to assist in getting fuel into the combustion chamber, but they do not typically rely on high RPM or exhaust gases to function, making them less effective in this context. Thus, exhaust primers are specifically engineered to operate based on the high RPM of the engine, highlighting their unique function in diesel fuel systems.