SMA WITH INSTRUCTOR AND SPI RUNS OUT OF GAS.

Narrative

DURING A PREFLT INSPECTION BEFORE A FLT FROM ELKO TO OGDEN I TOLD MY STUDENT NOT TO OPEN THE FUEL CAPS BUT JUST TO MAKE SURE THEY WERE TIGHT; THERE WAS SNOW AND WATER ON THE WINGS AND I DIDN'T WANT IT IN THE TANKS. WE KNEW THAT WE HAD PLENTY OF FUEL FOR THE TRIP (SUPPOSEDLY) BECAUSE WE LANDED WITH WELL OVER HALF TANKS THE NIGHT BEFORE AND THE FUEL GAUGES SHOWED FUEL IN THE TANKS. AS WE PASSED WENDOVER ON THE WAY TO OGDEN; MY STUDENT COMMENTED ON THE LOW FUEL READING FROM THE GAUGES -- I TOLD HIM NOT TO WORRY ABOUT IT BECAUSE THE GAUGES ARE ALWAYS PROFOUNDLY INACCURATE. AT APPROX 30 MI E OF WENDOVER I NOTICED THAT THE FUEL GAUGES WERE 'PEGGED' ON EMPTY. I TOLD MY STUDENT THAT WE WOULD RUN ON THE L TANK FOR A WHILE JUST TO GET AN IDEA OF HOW MUCH FUEL IS REALLY IN THE TANKS (COMPARING L TO R BECAUSE THEY WERE ABOUT EVEN). ABOUT 30 SECONDS AFTER I SWITCHED FROM 'BOTH' TO 'L' THE ENG QUIT; SO I IMMEDIATELY HEADED BACK TOWARD WENDOVER WITH THE ENG RUNNING ON 'BOTH.' I FOLLOWED A DIRT MAINT ROAD BACK INTO WENDOVER BUT PREPARED TO LAND ON THE DIRT ROAD. THE ENG WAS BEGINNING TO 'MISS' DURING THE LAST COUPLE OF MINS SO I ELECTED TO LAND ON THE CLOSED RWY 21 RATHER THAN TAKING THE CHANCE ON NOT MAKING THE RWY BY SETTING UP A PATTERN FOR RWY 30. I KNEW THAT THE CONDITION OF THE RWY WAS SUITABLE FOR LNDG A LIGHT PLANE AND I ALSO KNEW THAT THERE WAS NO CONSTRUCTION GOING ON BECAUSE IT WAS CLR JUST MINS BEFORE WHEN I PASSED THE ARPT. I STILL DO NOT KNOW WHAT REALLY HAPPENED TO OUR FUEL. IT COULD HAVE BEEN TAMPERED WITH IN ELKO OR MAYBE MY STUDENT INCORRECTLY MEASURED IT ON THE PREFLT TO ELKO. I HAVE LEARNED THAT IN THE FUTURE; I WILL PERSONALLY CHK THE FUEL QUANTITY (AND OTHER BASIC PREFLT ACTIONS) INSTEAD OF TAKING SOLELY MY STUDENT'S WORD ON IT. ALSO I HAVE LEARNED THAT I MUST COMPLETE AT LEAST A 'WALK AROUND' CHK INCLUDING VISUAL OF THE FUEL FOR EVEN THE SHORTEST STOPOVER -- EVEN IF ITS 5 MINS LONG. THIS SIT WON'T HAPPEN AGAIN.