A regulator for adding supplemental fuel from a fuel tank into an airflow duct which feeds air into a diesel engine for combustion as a supplemental fuel, comprising:
- a body casing having oppositely facing first and second recesses separated by a partition wall;
- a first diaphragm which forms one side of said first recesses to provide a first chamber, into which fuel from said fuel tank is admitted;
- a first end cap which attaches to said body casing, which encloses said first diaphragm, and which includes a spring which presses against said first diaphragm, and a spring adjusting means for adjusting said spring, for applying variable and yielding pressure to said first diaphragm;
- a maximum pressure adjusting means, which is adjustable by a user to select a maximum pressure of said fuel in said first chamber, in which said maximum pressure adjusting means comprises a diaphragm which is deflected by a spring;
- a spring tensioning screw which is used to adjustably bias said spring;
- a lever which is attached to said diaphragm and operatively connected to said fuel inlet valve;
- a fuel inlet valve, which admits fuel into said first chamber to maintain a pressure set by said maximum pressure adjusting means, which is comprised of:
- a valve body which defines an orifice, with a plunger seat at one end, through which fuel flows;
- a plunger which is tapered on one end, and which adjustably blocks said orifice by contacting said plunger seat;
- a spring, which is biased to press said plunger into said plunger seat of said orifice;
- and
- a cap, which connects to said valve body and which holds said spring in biased engagement with said plunger inside said orifice of said valve body;
- wherein when said plunger is pressed away from engagement with said valve seat, fuel is allowed to flow through said orifice, and when plunger is pressed into said valve seat, fuel is blocked from flowing through said fuel inlet valve;
- a second diaphragm which forms one side of said second recess to provide a second chamber, into which fuel from said first chamber is admitted, and from which fuel is routed to said airflow duct of said diesel engine;
- a second end cap which attaches to said second chamber, and which encloses said second diaphragm;
- a fuel control valve which is in said partition wall, which admits fuel into said second chamber from said first chamber at a rate controlled by a fuel flow adjusting means;
- a fuel flow adjusting means which varies a rate of delivery of said fuel through said fuel control valve according to engine vacuum;
- a fuel outlet port, which passes through said body casing wall in said second chamber, and is connected to a vacuum line from said diesel engine, and from which fuel is drawn from said second chamber into said airflow duct of said engine;
- wherein said fuel regulator is located outside said airflow duct and provides supplemental fuel to a diesel engine.