A diesel pump or as it is regularly known an injection pump typically is used to fuel a diesel engine, injection pumps can be utilized to deliver fuel to a petrol engine also. A diesel pump, in the first engines, would have been powered by the engine using a connection directly to the engines crankshaft. The diesel pump will be timed to inject the diesel into the engine at the correct time in the pistons stroke.
Commonly a diesel engine in your standard car, van or lorry will be of the four stroke variety, larger engines used in ships and large machinery will frequently be of the two-stroke variety to raise fuel efficiency. Two-stroke engines you would as a rule find in a strimmer or model car, of course these use petrol to run.
The main variation with a two-stroke engine is that the first and ultimate strokes are performed simultaneously, this has the consequence of drastically increasing efficiency at the price of a dirtier exhaust. Another benefit is that two-stroke engines can be effortlessly run in reverse, providing a reverse function without the requirement for intricate gearing mechanisms. In the up to date motor there are two main sorts of diesel engine, those are the common rail diesel engine and the electronic unit direct injection.
An electronic unit direct injection assembly combines the injector and diesel pump into a singe unit, the diesel pump is, commonly, still driven by the engine. An Overhead Camshaft (OHC) drives the diesel pumps and injectors, this is an assemblage sat on top of the engine and fixed directly to the engines main cam shaft by chain, or more commonly now, a belt.
The common rail diesel engine consist of a high pressured fuel rail, in essence a manifold, supplying single diesel fuel injectors versus the diesel pump delivering fuel directly to the fuel injectors.
As mentioned, above, your recent diesel engine works on a four stroke cycle. You may well have heard this named the Otto cycle after the inventor of the petrol motor, Nikolaus August Otto in 1876. A few years afterward Rudolf Diesel came along and, wishing to invent a more fuel efficient motor, came up with the diesel engine in 1892.
Diesel engines have been a bit sluggish on the up-take, for the typical everyday van, largely due to their reputation of being noisy and smelly. Obviously this is changing as modern technology makes the diesel engine a more acceptable resolution to our current transportation woes.
The four independent events or strokes in a typical four stroke diesel engine are as follows:
The Intake Stroke: As the piston reaches the top of it’s stroke and starts to move downward the air intake valve is opened, this has the result of air being drawn in as the piston moves down.
The Compression Stroke: As the piston hits the bottom of it’s stroke the air intake valve will close, as the outlet valve is also closed the air contained in the piston chamber is compressed as the piston travels back up the shaft.
The Combustion Stroke: As the piston reaches the top of the compression stroke diesel is injected at the precise moment by the diesel pump and as the piston is fractionally past the top of the upward part of the compression stroke the fuel to compressed air combination is ignited. This is where the energy to drive the vehicle is produced, the piston is forced down driving the motor.
The Exhaust Stroke: During the pistons last upward stroke the outlet valve is opened and the gases produced from the ignition of the air to fuel mixture is forced out and into the exhaust system. At the end of this stroke the four strokes are complete and the whole cycle starts again from the start.
One downside to diesel fuel as opposed to petrol is when used in very cold climates. Diesel will begin to freeze at a higher temperature than gasoline, this will start off by the diesel becoming thicker and waxy, clearly this will hinder the good running of any diesel engine. One technique is to put a tiny amount of petrol into the diesel fuel mix to help lower the freezing point of the overall mixture.
This additionally has the additional gain of making the overall combination more explosive, however too great a mixture can damage a diesel engine, even small amounts of petrol in a common rail engine can cause critical problems so talk to an experienced mechanic before varying your fuel combination.
Another problem that can be easily spotted is if your diesel pump is malfunctioning, this has the outcome of reduced fuel supply or pressure to the fuel system. Key symptoms are a failure of the engine to start, a lumpy or noisy combustion, or a high pitched whining coming from the engine. You will probably also spot a lack of performance when applying the throttle. If any of these scenarios arise it would be recommended to get your car checked out by a mechanic who may need to source you a new diesel pump.
About the Author. Andrew is a web designer by trade and is now starting to author and write articles alongside running his web design business.
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