Fuel injection cleaning and testing system and apparatus

An apparatus for cleaning and/or testing the fuel injection valve system of a vehicle engine, wherein said apparatus defines an independent fuel system attachable to the vehicle engine so as to temporarily replace the engine's fuel system, the apparatus comprising:

• a fuel/chemical mixture tank having an outlet line and a return line in communication, respectively, with fuel inlet and outlet ports of the engine for communicating fuel to one of the fuel injectors;
• fuel pump means, separate and apart from the vehicle engine, for pumping fuel/chemical mixture from said tank into the fuel inlet port of said engine;
• a fuel filter interposed in said fuel line and between the mixture tank and the fuel pump;
• a first sensor means, interposed between the pump and the filter, for detecting the fluid pressure drop across the filter during operation of the pump and generating a first signal;
• a second sensor means, downstream of the pump, for detecting the fluid pressure at the inlet to the engine and generating a second signal;
• and
• electronic control means for controlling the operation of the pump during operation of the engine being cleaned, said control means including
• first circuit means, connected to the pump and responsive to said first signal, for operating the pump in a fuel feeding mode when the pressure drop is below a predetermined threshold and deactivating the pump when the pressure drop exceeds the predetermined threshold, and
• second circuit means, connected to the pump and responsive to said second signal, for operating the pump in a fuel retracting mode whereby to draw the cleaner fluid back to the mixture tank via the outlet line, said first and second circuit means being connected in series with one another.