Narrative:

In cruise flight at 10000 ft; the fuel flow from a tank containing 70 gallons of jet a refused to flow and resulted in a low fuel warning from the header tank. With the lack of fuel flow; it gives about 15 mins of fuel to land. I declared a fuel related emergency and flew an emergency ILS approach into ZZZ in low IFR conditions. The flight was never in any danger as long as I landed within 15 mins. A gas cap seal was found to have partially unseated and resulted in a venting problem for that tank. It has been rectified. The low IMC was contributing to the difficulty of the situation and the inability to continue flight without implementing a corrective action. All approach charts and en route left charts were on board and current; the controller was impeccable in her assistance to getting me quickly onto the approach and an uneventful outcome. After corrective action; the rest of the flight was conducted safely after the WX conditions improved. This was the first emergency I have ever declared and chose to declare it due to the difficult WX conditions that might have caused a missed approach and a different outcome. If I was in VMC; I would have made a quick landing under visual conditions and not needed to declare an emergency.

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Original NASA ASRS Text

Title: HOME BUILT TURBO PROP MAKES EMERGENCY LNDG WHEN PLT IS UNABLE TO ACCESS FUEL IN TANK WITH MALFUNCTIONING VENTING SYSTEM.

Narrative: IN CRUISE FLT AT 10000 FT; THE FUEL FLOW FROM A TANK CONTAINING 70 GALLONS OF JET A REFUSED TO FLOW AND RESULTED IN A LOW FUEL WARNING FROM THE HEADER TANK. WITH THE LACK OF FUEL FLOW; IT GIVES ABOUT 15 MINS OF FUEL TO LAND. I DECLARED A FUEL RELATED EMER AND FLEW AN EMER ILS APCH INTO ZZZ IN LOW IFR CONDITIONS. THE FLT WAS NEVER IN ANY DANGER AS LONG AS I LANDED WITHIN 15 MINS. A GAS CAP SEAL WAS FOUND TO HAVE PARTIALLY UNSEATED AND RESULTED IN A VENTING PROB FOR THAT TANK. IT HAS BEEN RECTIFIED. THE LOW IMC WAS CONTRIBUTING TO THE DIFFICULTY OF THE SITUATION AND THE INABILITY TO CONTINUE FLT WITHOUT IMPLEMENTING A CORRECTIVE ACTION. ALL APCH CHARTS AND ENRTE L CHARTS WERE ON BOARD AND CURRENT; THE CTLR WAS IMPECCABLE IN HER ASSISTANCE TO GETTING ME QUICKLY ONTO THE APCH AND AN UNEVENTFUL OUTCOME. AFTER CORRECTIVE ACTION; THE REST OF THE FLT WAS CONDUCTED SAFELY AFTER THE WX CONDITIONS IMPROVED. THIS WAS THE FIRST EMER I HAVE EVER DECLARED AND CHOSE TO DECLARE IT DUE TO THE DIFFICULT WX CONDITIONS THAT MIGHT HAVE CAUSED A MISSED APCH AND A DIFFERENT OUTCOME. IF I WAS IN VMC; I WOULD HAVE MADE A QUICK LNDG UNDER VISUAL CONDITIONS AND NOT NEEDED TO DECLARE AN EMER.

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.