FLUSH TYPE GAS CAP HAS SEAL DETERIORATION WHICH ALLOWS GAS TO SIPHON IN FLT. FAULTY FUEL INDICATION. ENG QUITS. FORCED LNDG.

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FREEZING CONDITIONS AT GRAND CANYON ARPT PROBABLY CONTRIBUTED TO THE DETERIORATION OF THE GAS CAP SEALS ON MY SMA (ORIGINAL SMA FLUSH MOUNTED CAPS). UNKNOWN TO ME; GAS WAS BEING SIPHONED OUT THROUGH THE GAS CAPS (MOSTLY FROM THE R TANK). AFTER NEARLY 3 HRS OF FLYING; THE FUEL TOTALIZER INDICATED THAT I HAD USED 35 GALLONS WITH 45 GALLONS OF FUEL REMAINING. THE L FUEL GAUGE WAS SHOWING THAT THE L TANK WAS NEARLY EMPTY. THIS WAS SLIGHTLY LOWER THAN I EXPECTED EVEN THOUGH I HAD BEEN RUNNING MOSTLY FROM THE L TANK. THE R FUEL GAUGE HOWEVER; WAS STILL SHOWING NEARLY FULL; AND SLIGHTLY HIGHER THAN WHAT I EXPECTED. AT THAT TIME I LOOKED FOR LEAKING FUEL BUT DID NOT SEE ANY. I DECIDED TO CUT MY FLT SHORT TO INVESTIGATE BY LNDG AT LA JUNTA; APPROX 25 MI AHEAD. A FEW MINS LATER; THE ENG DIED OF FUEL STARVATION. I CONTACTED PUEBLO APCH ON 121.5 (AND LATER ON 120.1). THE CTLR SUGGESTED FOWLER FIELD ABOUT 10-12 MI TO THE N. (I WAS APPROX 29 NM SE OF PUEBLO VOR ON THE 134 DEG RADIAL.) I DETERMINED THAT BOTH FOWLER AND NEARBY MELON WERE OUT OF GLIDING RANGE. THE PAVED ROAD BELOW LOOKED LIKE A GOOD LNDG SPOT; WITH SURROUNDING FIELDS AS A BACKUP IF PWR LINES OR OTHER OBSTRUCTIONS PREVENTED USE OF THE ROAD. SWITCHING TO THE BOTH TANK POS DID NOT RESTART THE ENG; BUT USING THE ELECTRIC BOOST PUMP RESTARTED THE ENG. THE RESTART GAVE ME ENOUGH ALT THAT I THOUGHT I COULD GLIDE TO MELON FIELD NOW ABOUT 7 MI NE. THE CTLR WAS GENERALLY HELPFUL EXCEPT AT 1 POINT WHERE HE SAID THAT MELON WAS 12 O'CLOCK AT 1 MI; WHEN IT WAS REALLY 5 MI AWAY. HE EVENTUALLY CORRECTED HIMSELF; BUT THIS ADDED TO THE DIFFICULTY OF FINDING A FAIRLY HARD TO SEE STRIP. WHEN I FINALLY SAW MELON; IT WAS 3 OR 4 MI AWAY. AT ABOUT 2 MI FROM MELON; I REALIZED I WAS GOING TO BE ABOUT 1/2 A MI SHORT; AND ELECTED TO LAND IN A NEARBY ALFALFA FIELD. PLTS AT MELON SAW ME LAND AND CAME OUT TO HELP. AFTER WE DISCOVERED THE FUEL LEAK AND DETERMINED THAT THE AIRPLANE WAS OUT OF GAS; THEY WENT BACK TO MELON TO GET GAS. I ALSO NOTICED THAT THE FUEL BLADDERS HAD FLOATED UP TOWARDS THE TOP OF THE TANK; EXPLAINING THE ERRONEOUS FUEL GAUGE READINGS. WITH 10 GALLONS OF GAS ADDED; AND PERMISSION FROM THE FARMER; I TOOK OFF FROM THE FIELD AND LANDED AT MELON ARPT. TO HELP GETTING OFF THE SHORT AND MUDDY FIELD; MY PAX AND SOME OF OUR BAGGAGE WENT TO MELON BY CAR. WE FUELED UP WITH AN ADDITIONAL 72.3 GALLONS; VERIFYING THAT THE AIRPLANE HAD RUN OUT OF GAS. (FUEL CAPACITY IS SPECIFIED AS 80 GALLONS TOTAL.) WE THEN WENT ON OUR WAY; AFTER BEING CAREFUL THAT THE FUEL CAPS WERE INSTALLED PROPERLY. HOWEVER; WE COULD SEE THAT FUEL WAS STILL LEAKING OVERBOARD. WE LANDED AT LAMAR; CO; WHERE A MECH REPLACED 2 OF OUR FUEL CAPS WITH A SIMILAR KIND. WE WERE ABLE TO CONTINUE THE FLT THE NEXT MORNING; HOWEVER; I SUSPECT THAT SMALL AMOUNTS OF FUEL WERE STILL LEAKING. AFTER HEARING OF THE MANY PROBLEMS RPTED WITH THE FLUSH FUEL CAPS; I HAVE DECIDED TO REPLACE THEM WITH AN AFTER- MARKET REPLACEMENT THAT INCLUDES AN ANTI-SIPHON VALVE; WHICH WILL PREVENT LOSS OF FUEL EVEN IF THE GAS CAP IS LEFT OFF. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES HE HAS HEARD SINCE HIS INCIDENT THAT HALF THE MANUFACTURER'S SMT'S HAVE REPLACEMENT CAPS. MANUFACTURER DOES NOT MAKE THESE FLUSH CAPS ANY LONGER BUT HAS A REPLACEMENT WHICH RPTR INSTALLED. ANOTHER MANUFACTURER MAKES THE ANTI-SIPHON VALVE WHICH WORKS LIKE THE METAL FLAPPER VALVE IN CARS TO PREVENT REVERSE FLOW OF FUEL.