A GRUMMAN GA-7 PLT OWNER RPTS IN CRUISE AT 4000 FT DIVERTED DUE TO L ENG RAN OUT OF FUEL. SWITCHED TO XFEED; ENG OPERATED NORMALLY. RPTR CONCLUDED OLDER AIRPLANES BURN MORE FUEL THAN OPERATING HANDBOOK PRESCRIBED.

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HAVING TAKEN THIS ACFT FROM FLORIDA TO OMAHA THIS PAST SUMMER; I HAD A GOOD FEEL FOR ITS BURN RATES. IT PROVED TO ME WHAT THE OPERATING HANDBOOK SUBSCRIBED. BTWN THE SUMMER AND MY RECENT TRIP TO SEE SOME FAMILY IN GEORGIA; THE ACFT'S ENGS EVIDENTLY SEEM TO BE BURNING MUCH MORE FUEL THAN NORMAL. NEVERTHELESS; HAVE PLANNED MY FLT OUT LIKE NORMAL I HAD PLENTY OF FUEL (45 MINS MINIMUM AND BEYOND) TO MAKE IT TO MY DEST. HOWEVER; OVER ZZZ FIELD THE L ENG STARTED TO SPUTTER IMMEDIATELY ADVANCING MIXTURE PROPS AND THROTTLES FORWARD IT CONTINUED UNTIL I INTRODUCED XFEED TO THAT ENG. THE ENG STABILIZED AND I PROCEEDED TO TELL APCH THAT I WANTED TO DEV FOR FUEL. THEY CANCELED IFR SVC AND GAVE ME THE WX INTO ZZZ WHERE I STARTED TO CIRCLE DOWN AND WORK WITH TWR. UNFORTUNATELY TFC WAS REAL HIGH FOR THE CURRENT TIME BUT TWR KNEW ABOUT OUR MINIMUM FUEL SITUATION AND SQUEEZED US BTWN TFC AND MADE A FULL STOP LNDG. EVERYTHING FROM THEN ON WAS NORMAL. CASE IN POINT; SOMETHING WAS WRONG WITH THE ENGS. I CALCULATED THAT THEY BURNED APPROX 33% MORE THAN USUAL. THEREFORE; THE ENTIRE SITUATION WAS A HUGE LEARNING EXPERIENCE AND I URGE PLTS TO TAKE IN THE FACT THAT OLDER ACFT DON'T BURN WHAT IS PRESCRIBED IN THE POH.