The present invention relates to diesel engines, and, more particularly, to a method and apparatus for assuring that a diesel engine is used only with a fuel designed specifically for operation in the engine. Diesel engines are well known in the art and multi-cylinder diesel engines have long been used in powering large machinery such as locomotives and over-the-road trucks. Smaller multi-cylinder diesel engines have also been adapted for use in certain automobiles. Currently, even smaller single cylinder diesel engines have been developed for use in relatively low power applications. All of these diesel engines routinely produce high levels of hydrocarbon emissions and are therefore not particularly environmentally friendly. Applicant has found that the hydrocarbon and other emissions from such diesel engines can be significantly reduced by utilization of a bio-diesel fuel in the engines. In particular, applicant has found that the use of a fuel manufactured from used vegetable oil can be used in these engines and will cause the engines to fall well within the emissions guideline of the United States Environmental Protection Agency. The problem that the EPA has with such engines is that the fuel source must be controlled in such a manner as to prevent conventional hydrocarbon-base diesel fuel from being used in such engine. If a user of such engine substitutes ordinary hydrocarbon-base diesel fuel into the engines, the emissions from the engine will likely exceed the EPA requirements and thus result in an engine which produces environmentally harmful pollutants.
An example of a single cylinder diesel engine is a Model 186F available from ETQ Power Products of Baldwin Park, Calif. The Model 186F diesel engine is rated at 10 horsepower but has been known to produce significant hydrocarbon emissions when operating on conventional hydrocarbon-base diesel fuel. This same engine has been tested with bio-diesel fuel manufactured from used vegetable oil and found to produce emissions that are well below conventional EPA guidelines when using this alternative fuel. Accordingly, EPA may approve use of this engine in the U.S. if the engine can be limited to operation on bio-diesel fuel.
Applicant has found that one method of preventing substitution of hydrocarbon based diesel fuel into a diesel engine is to provide a fuel tank for use on such engines that is not refillable by the user of the engine. For example, the fuel tank is not provided with a refill cap of the conventional type. In applicant's invention, the fuel tank is removable from the engine and must be returned to a dealer in such fuel tanks for replacement. Only the dealer has the equipment necessary to refill the tank and to restore it to its normal operating condition. For this purpose, the fuel tank must be readily removable from the diesel engine and easily attachable to the engine in order to allow the consumer to replace the tank as necessary. Further, the attachments to the engine should be designed in such a manner that they cannot be bypassed so as to allow a user to connect a different type of tank to the engine.