Narrative:

I was on a VFR flight when the engine started to slow down. It seemed like it was running out of gas; so I used the primer and it helped. I located the nearest airport; and headed for runway 17. The primer eventually quit keeping the engine running; and I landed short of the runway in a field; but on airport property. After a muddy touchdown; I opened the fuel cap on the left wing to check for fuel; which the gauges read both tanks at 1/3. The tank 'expanded' as I loosened the cap. There was fuel in the tank; but it seemed like the tank had a 'vacuum' on it. After towing the aircraft to the repair hangar; the mechanic said the fuel vent tube was plugged; and this was most likely the cause of the engine slow down and stall. No aircraft or property was damaged.

Related reports:

Google
 

Original NASA ASRS Text

Title: A C150 IN CRUISE AT 3000 FT EXPERIENCED THE ENG LOSING PWR. DIVERTED TO NEAREST ARPT. ENG QUIT AND ACFT LANDED SHORT BUT ON ARPT.

Narrative: I WAS ON A VFR FLT WHEN THE ENG STARTED TO SLOW DOWN. IT SEEMED LIKE IT WAS RUNNING OUT OF GAS; SO I USED THE PRIMER AND IT HELPED. I LOCATED THE NEAREST ARPT; AND HEADED FOR RWY 17. THE PRIMER EVENTUALLY QUIT KEEPING THE ENG RUNNING; AND I LANDED SHORT OF THE RWY IN A FIELD; BUT ON ARPT PROPERTY. AFTER A MUDDY TOUCHDOWN; I OPENED THE FUEL CAP ON THE L WING TO CHK FOR FUEL; WHICH THE GAUGES READ BOTH TANKS AT 1/3. THE TANK 'EXPANDED' AS I LOOSENED THE CAP. THERE WAS FUEL IN THE TANK; BUT IT SEEMED LIKE THE TANK HAD A 'VACUUM' ON IT. AFTER TOWING THE ACFT TO THE REPAIR HANGAR; THE MECH SAID THE FUEL VENT TUBE WAS PLUGGED; AND THIS WAS MOST LIKELY THE CAUSE OF THE ENG SLOW DOWN AND STALL. NO ACFT OR PROPERTY WAS DAMAGED.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.