Narrative:

At 11000 ft near akron, oh, in cruise flight, I noticed the fuel pressure begin to fall, and shortly thereafter a drop in manifold pressure. I began troubleshooting procedures (alternate air, switch fuel tanks, mixture, fuel pump on, magnetos, etc), and when it became apparent nothing was working, advised ATC I wanted to head to akron airport, due to the fact I was only getting partial power. ATC gave vectors to the airport, and while descending, I continued to troubleshoot the problem. I could only get the engine to run at approximately 1000-1300 RPM. Any further advance of the throttle would result in the engine bogging down. I asked ATC if there was a closer airport and was advised kent state airport and akron fulton were, and received vectors for kent state. Somewhere between 3000 ft and 4000 ft MSL I tried advancing the throttle and was able to obtain full power. At that point I asked to continue to akron-canton airport. En route, the controller asked if I wanted the 'equipment' to be deployed or standing by and I declined. I broke out under the broken overcast layer, saw the airport and was cleared for a visual approach. After landing, the aircraft was checked by a mechanic and no problems were found. He suspected there may have been some water in the fuel system which froze. No water was noted on preflight, however, a larger sample and waiting longer after fueling may have indicated the presence of some if the problem was indeed caused by water.

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Original NASA ASRS Text

Title: SMA PLT HAS PARTIAL PWR LOSS, FALLING FUEL PRESSURE AND MANIFOLD PRESSURE. AFTER TROUBLESHOOTING RPTR REQUESTS VECTORS TO NEAREST ARPT. MECH CAN FIND NO PROB.

Narrative: AT 11000 FT NEAR AKRON, OH, IN CRUISE FLT, I NOTICED THE FUEL PRESSURE BEGIN TO FALL, AND SHORTLY THEREAFTER A DROP IN MANIFOLD PRESSURE. I BEGAN TROUBLESHOOTING PROCS (ALTERNATE AIR, SWITCH FUEL TANKS, MIXTURE, FUEL PUMP ON, MAGNETOS, ETC), AND WHEN IT BECAME APPARENT NOTHING WAS WORKING, ADVISED ATC I WANTED TO HEAD TO AKRON ARPT, DUE TO THE FACT I WAS ONLY GETTING PARTIAL PWR. ATC GAVE VECTORS TO THE ARPT, AND WHILE DSNDING, I CONTINUED TO TROUBLESHOOT THE PROB. I COULD ONLY GET THE ENG TO RUN AT APPROX 1000-1300 RPM. ANY FURTHER ADVANCE OF THE THROTTLE WOULD RESULT IN THE ENG BOGGING DOWN. I ASKED ATC IF THERE WAS A CLOSER ARPT AND WAS ADVISED KENT STATE ARPT AND AKRON FULTON WERE, AND RECEIVED VECTORS FOR KENT STATE. SOMEWHERE BTWN 3000 FT AND 4000 FT MSL I TRIED ADVANCING THE THROTTLE AND WAS ABLE TO OBTAIN FULL PWR. AT THAT POINT I ASKED TO CONTINUE TO AKRON-CANTON ARPT. ENRTE, THE CTLR ASKED IF I WANTED THE 'EQUIP' TO BE DEPLOYED OR STANDING BY AND I DECLINED. I BROKE OUT UNDER THE BROKEN OVCST LAYER, SAW THE ARPT AND WAS CLRED FOR A VISUAL APCH. AFTER LNDG, THE ACFT WAS CHKED BY A MECH AND NO PROBS WERE FOUND. HE SUSPECTED THERE MAY HAVE BEEN SOME WATER IN THE FUEL SYS WHICH FROZE. NO WATER WAS NOTED ON PREFLT, HOWEVER, A LARGER SAMPLE AND WAITING LONGER AFTER FUELING MAY HAVE INDICATED THE PRESENCE OF SOME IF THE PROB WAS INDEED CAUSED BY WATER.

Data retrieved from NASA's ASRS site as of July 2007 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.