the inventive fuel system includes a fuel pump 2 which receives liquid fuel ( alcohol ) from source 4 through fuel line 6 . fuel pump 2 supplies fuel either to alcohol carburetor 8 via fuel line 10 , fuel valve 12 and fuel line 14 or to primary vaporizer 16 via fuel line 18 , fuel valve 20 and fuel line 22 . that is , when 3 - position switch 24 is placed in position &# 34 ; 2 &# 34 ; ( i . e . the liquid position ), valve 12 opens , valve 20 closes , and fuel is supplied to alcohol carburetor 8 . however , when switch 24 is placed in position &# 34 ; 3 &# 34 ; ( i . e . the vapor position ), valve 12 closes , valve 20 opens and fuel is supplied to primary vaporizer 16 . vaporized fuel passes from primary vaporizer 16 to secondary vaporizer 26 via vapor hose 28 where the fuel is super vaporized . hot water is supplied to vaporizers 16 and 26 , via hot water line 30 and 32 respectively , by water pump 34 which is coupled to the engine &# 39 ; s cooling system ( not shown ). after the hot water has been utilized by vaporizers 16 and 26 , it may be returned to the vehicle &# 39 ; s heater via line 36 . in summer , a bypass could be used to bypass the heater so as to permit circulation with the heater off . the super vaporized fuel is conveyed via vapor hose 38 to a liquid petroleum ( lp ) carburetor 40 . from there , the vaporized fuel is drawn into the engine via line 42 and carburetor 8 . the system operates as follows . when starting the engine , switch 24 ( which may be mounted on the vehicle &# 39 ; s dashboard and is electrically coupled to valves 12 and 20 and to the vehicle &# 39 ; s electrical system ) is placed in position &# 34 ; 2 &# 34 ; thereby permitting liquid alcohol to flow to carburetor 8 . in this case , the vehicle will operate in the well known manner ; i . e . liquid fuel will be drawn into the engine via carburetor 8 and converted into energy . when engine temperature reaches approximately 180 ° f .- 190 ° f . switch 24 is placed in position &# 34 ; 1 &# 34 ; which causes both valves 12 and 20 to close . when the engine is about to stall as a result of lack of fuel , switch 24 is placed in position &# 34 ; 3 &# 34 ; ( vapor ), and fuel pump 2 will pump fuel to the primary and secondary vaporizers 16 and 26 respectively . when the fuel is vaporized , it is drawn into the engine intake manifold 46 , by the engine &# 39 ; s vacuum , through hose 38 , lp carburetor 40 , hose 42 , and into the air intake of carburetor 8 . at this point , the engine is running entirely on vapor being supplied by lp carburetor 40 . alcohol carburetor 8 merely controls the engine &# 39 ; s vacuum permitting the lp carburetor 40 to function and controls the vacuum for the distributor automatic timing advance mechanism . both functions are controlled by the throttle plate 44 in the alcohol carburetor . lp carburetor 40 is controlled entirely by engine vacuum . for example , when the engine is operating at a slow idle speed , the throttle plate in carburetor 8 will be nearly closed providing very little vacuum to lp carburetor 40 which in turn releases very little vapor . when the throttle plate in carburetor 8 is open , a very high vacuum is produced causing lp carburetor to release a large quantity of vapor . when the engine is to be turned off , switch 24 should first be placed in position &# 34 ; 1 &# 34 ; until the engine is about to stall and then be placed in position &# 34 ; 2 &# 34 ; ( liquid ). this will cause the fuel bowl in carburetor 8 to fill to its proper level so as to permit the engine to be restarted after it has cooled . furthermore , by operating the engine with switch 24 in position &# 34 ; 1 &# 34 ;, all fuel provided by the system prior to the switch is burned preventing engine operation or both liquid and vapor fuel simultaneiously . the components of the inventive fuel system are well known and commercially available . for example , vaporizers 16 and 26 may be of the type bearing model number m6 and manufactured by century gas equipment company . the lp carburetor 40 may be an imperial 300a manufactured for century gas equipment company , and valves 12 and 20 may be electrically operated solenoid fuel valves bearing model number 2341 likewise manufactured by century gas equipment company . the above description is given by way of example only . changes in form and details may be made by one skilled in the art without departing from the scope of the invention . for example , the system is not limited to using alcohol as a fuel . additionally , when starting the engine in below freezing temperatures , a windshield washer arrangement containing gasoline or other fuel may be used to prime the engine . a manual choke would also be helpful . various changes and modifications to the embodiment herein chosen for purposes of illustration will readily occur to those skilled in the art . to the extent that such variations and modifications do not depart from the spirit of the invention , they are intended to be included within the scope thereof which is assessed only by a fair interpretation of the following claims .