Carburetion and Fuel Injection Questions and Answers

Answer: A

The apparatus is the carburettor.

In a petrol (spark-ignition) engine, the carburettor atomises petrol into the air stream drawn into the engine, producing an air-fuel mixture in the right proportion for combustion. Modern engines mostly use fuel injection instead, but the carburettor is the classic device.

Callipers measure lengths and diameters, a chronometer is a precision clock used in navigation, and an electrometer measures electric charge or potential difference. None of them mixes fuel with air.

Answer: C

The device is the carburetor.

In a petrol (spark ignition) engine the carburetor breaks the fuel into a fine spray as air rushes through its venturi, vaporises it and mixes it with the air in the right proportion before the charge enters the cylinder.

The choke is only a valve in the carburetor's air passage that enriches the mixture for a cold start; it does not atomise anything by itself. The piston compresses the charge, and the battery supplies the ignition and electrical system.

Answer: B

A carburetor supplies petrol and air.

The carburetor is fitted to petrol (spark ignition) engines. It meters petrol into the air stream passing through it and delivers a combustible petrol-air mixture to the inlet manifold.

Diesel engines draw in air alone and inject the fuel directly, so they have no carburetor, which rules out the options with diesel. Lubricating oil is not supplied by the carburetor either: in two-stroke petrol engines it is premixed with the petrol in the tank.

Answer: B

The keyed answer is the rack and pinion arrangement.

In the fuel injection pump of a diesel engine, each plunger has a helical groove. A control rack engages a pinion (toothed sleeve) on each plunger, so moving the rack rotates the plungers and changes the effective stroke during which fuel is delivered. This is how the quantity of diesel injected per cycle is set.

The governor or the accelerator moves the rack, but the metering itself is done through the rack and pinion. The nozzle only atomises the fuel, and diesel engines have no throttle on the fuel, unlike petrol engines.

Answer: B

The process is called carburation.

In an SI engine the carburettor atomises and vaporises petrol and mixes it with air in the correct proportion before the charge enters the cylinder. This preparation of the mixture is carburation.

Ignition is starting combustion with the spark, scavenging is clearing burnt gases from the cylinder, and 'firing of engine' is not the term for mixing.

Answer: C

The key's answer is steam generator.

A fuel injector sprays fuel into the cylinder or intake of an internal combustion engine. A diesel engine depends on it, and modern SI engines, two stroke as well as four stroke, also use port or direct fuel injection in place of a carburettor.

A steam generator is a boiler, an external combustion device in which fuel is burnt in a furnace to raise steam, so it has no fuel injector of the engine kind. Older carburetted SI engines also lack injectors, but the key treats the steam generator as the device to which injectors do not belong.