Background of the Invention Fuel injection systems are often cleaned as part of routine maintenance, or scheduled servicing of vehicles.

The cleaning of a fuel injection system typically involves pumping a solvent through the fuel injection system for the purposes of flushing the system and cleaning debris and deposits from the injectors and an associated pressure regulator of the system. However, to a vehicle owner, it is not always apparent that the fuel injection system of their vehicle has actually been cleaned even when the owner is present when the cleaning takes place. Further, even when the fuel injection system is properly cleaned by a reputable service provider, current fuel injection cleaning methods are unable to detect certain malfunctions of the fuel injection system.

The present invention was developed with a view to attempting to overcome the abovementioned deficiencies in the prior art.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word"comprise"or variations such as "comprises"or"comprising"is used in an inclusive sense, i. e. to specify the presence of the stated features but

not to preclude the presence or addition of further features in various embodiments of the invention.

Summary of the Invention According to the present invention there is provided an apparatus for cleaning a fuel injection system of an internal combustion engine comprising: a pump; a canister holding a volume of a cleaning solution, said canister formed to enable visual inspection of said cleaning solution; a first conduit providing fluid communication between said pump and said fuel injection system; a second conduit providing fluid communication between said fuel injection system and said canister; a third conduit providing fluid communication between said canister and said pump; whereby, with said engine ON, cleaning solution is pumped by said pump through a circuit comprising said first conduit, fuel injection system, second conduit, canister and third conduit whereby said cleaning solution can be inspected in said canister as said solution flows through said circuit.

Preferably said apparatus further comprises a pressure gauge in fluid communication with said circuit to provide an indication of fluid pressure in said circuit.

Preferably said apparatus is constructed to maintain fluid pressure after said pump and said engine have been switched off, whereby a decrease in fluid pressure

indicated by said pressure gauge is indicative of a pressure leak in said fuel injection system.

Preferably said apparatus further comprises a bypass valve and a fourth conduit, said bypass valve in fluid communication with first and fourth conduits, said fourth conduit also in fluid communication with said canister, whereby fluid pressure in said circuit can be varied by manipulation of said bypass valve.

According to a further aspect of the present invention there is provided a method of cleaning and testing a fuel injection system of an internal combustion engine comprising: connecting a pump via a first conduit to said fuel injection system; connecting said fuel injection system to a canister containing a volume of a cleaning solution via a second conduit, said canister formed to allow visual inspection of said cleaning solution; connecting said canister to said pump via a third conduit ; and, with said engine ON, switching said pump ON to pump said cleaning solution through a circuit comprising said first conduit, said fuel injection system, second conduit, canister and third conduit, to clean said fuel injection system; and visually inspecting said cleaning solution as it passes through said canister.

Preferably said method further comprises: placing a pressure gauge in fluid communication with said circuit and, after cleaning said fuel injection system,

switching said pump and said engine OFF and inspecting said pressure gauge and said canister; whereby, a reduction in pressure indicated by said pressure gauge without additional flow of cleaning fluid through said canister provides an indication of a pressure leak in fuel injectors of said fuel injection system, while a decrease in fluid pressure accompanied by a flow of cleaning fluid through said canister is indicative of a pressure leak in a pressure regulator of said fuel injection system.

Description of the Drawings An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing which provides a schematic representation of an embodiment of an apparatus for cleaning a fuel injection system.

Detailed Description of Preferred Embodiment The apparatus 10 for cleaning a fuel injection system 12 of an internal combustion engine (not shown) comprises a pump 14 and a canister 16 which holds a volume of cleaning solution. The canister 16 is formed in a manner whereby a user can visually inspect the cleaning solution contained in and/or flowing through the canister. This may be achieved by constructing the canister 16 from a transparent material such as glass. Alternately, the canister 16 may be provided with one or more windows to allow visualisation of the cleaning solution. The pump 14 communicates with the fuel injection system 12 via a first conduit 18. A second conduit 20 communicates between the fuel injection system 12 and the canister 16. A third conduit 22 communicates between the canister 16 and the pump 14 to feed the cleaning solution to the pump. In

use, a volume of cleaning solution is initially placed in the canister 16, and the conduits 18 and 20 coupled to the fuel injection system 12 and canister 16 respectively.

Upon operation of the pump 14, cleaning solution is pumped through a circuit comprising the conduit 18, fuel injection system 12, conduit 20, canister 16, the conduit 22 and back through the pump 14. The solution can be recirculated for as long as required in order to properly clean the fuel injection system 12.

During this process, a user is able to inspect the cleaning solution as it flows through the canister 16 to provide visual verification of the cleaning process.

Foreign matter and deposits cleaned from the fuel injection system 12 will also appear entrained in the cleaning solution.

A pressure gauge 24 is in fluid communication with the circuit through which the cleaning solution flows to provide an indication of fluid pressure. The apparatus 14 is further constructed so that when the pump 14 is turned OFF (and an engine associated with the fuel injection system 12 is turned OFF), pressure is maintained by the pump 14 and canister 16. This has benefits in terms of testing the fuel injection system 12. In particular, a drop in the pressure indicated by the gauge 24 will be indicative of a pressure leak within the fuel injection system 12. This may arise from a pressure leak within individual injectors of the system 12 or alternately in an associated pressure regulator of the fuel injection system 12. The apparatus 10 is also able to differentiate between a leak in the fuel injectors themselves or the associated pressure regulator by inspecting the canister 16. If the reduction in pressure is accompanied by a flow of cleaning solution visualised through the canister 16, (when the pump 14 is OFF) this is indicative of a pressure leak in the pressure regulator rather than the injectors.

A drop in pressure indicated by the pressure gauge 24 without additional flow of cleaning solution into the canister 16 is indicative of a pressure leak within the fuel injectors.

A bypass valve 26 is placed in the first conduit 16 and is coupled at one end to a fourth conduit 28 which communicates with the canister 16. The bypass valve 26 can be operated to vary or regulate the fluid pressure within the circuit.

Thus, it would be appreciated that an embodiment of the present apparatus 10 allows both the user of this apparatus 10 and the owner of a vehicle whose fuel injection system 12 is being cleaning, to visually verify that cleaning is taking place and to also in the event of a"dirty"fuel injection system 12, see the effect of the cleaning process by witnessing a discolouration in the cleaning solution or entrainment of foreign particles as it passes through the canister 16. Additionally, the apparatus 10 allows testing of the fuel injection system 12 to detect pressure leaks in either the fuel injectors themselves or an associated pressure regulator and to also differentiate between a pressure leak in the fuel injectors and the pressure regulator.

A tap 30 is provided at a lower end of the canister 16 to allow draining of the cleaning solution after every job.

If desired, used solution can be given to the customer.

In addition, graduations 32 may be marked on the canister 16 which can be used in the following manner to provide an indication of fuel consumption of an engine associated with the fuel injection system 12 and in particular to provide an indication of the difference in fuel consumption before and after cleaning of the fuel injection system 12. To this end, the canister 16 is initially filled with a volume of cleaning solution which

comprises a mixture of fuel and cleaning solvents which readily combust in an internal combustion engine. The volume may be say 1200ml and reach a first graduation 32a in the canister 16. The apparatus 10 can be operated for say 20 minutes. After an initial period of, say five minutes, a reading is taken of the consumption of solution by reference to the graduations 32. This may indicate for example a drop in solution level (ie consumption) of say five graduations). The cleaning process continues and after a further 10 minutes, the current solution level is noted a second five minute period commences. After the second five minute period a further solution level reading is taken to find the consumption of the solution in that second five minute period. This may for example be consumption of four graduations. Therefore the solution consumption is reduced by one graduation, ie 20% by the end of the cleaning process. This would relate to a certain percentage better fuel consumption a customer could expect.

It is envisaged that the pump 14 and canister 16 can be both mounted in a small case similar to a brief case so that the apparatus 10 is fully portable.

Now that embodiment of the present invention has been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, in a prototype the canister 16 is constructed with a cylindrical glass wall to allow visualisation of the cleaning solution passing therethrough. However as mentioned above, the entire side wall of the canister 16 need not be made from glass or another transparent material but rather have one or more windows located to allow visualisation of the cleaning solution passing through the canister 16. In addition, the canister 16 may take any desired shape including for

example, the shape of a conical frustum with a lower diameter end coupled to the conduit 22. Also, in place of the graduations 32, other liquid level measurement apparatus and devices may be used for the purposes of providing an indication of liquid volume within the system 10.

All such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the above description and the appended claims.