Bob Brown
Well Known Member
I have a 180hp Superior XP-360, with a Bendix fuel injection system. I have the standard AFP High Pressure boost pump system. My first flight went without problems, I climbed to 6000', did slow flight, stalls, cruised around at 4000', had no problems, landed. Second flight, shortly after turning off the boost pump after takeoff, the engine monitor showed the fuel pressure dropping. It dropped all the way down until the engine was starting to starve, when I turned the boost pump back on. Pressure was instantly back to 28psi and I felt a power surge as the engine got what it wanted. I cruised around the field for a few minutes thinking this through, then with the boost pump on, I switched tanks then turned the boost pump off. Pressure immediatly started dropping. Boost pump on. I then landed to diagnose. Immediately after turning off the runway, I turned off the boost pump. Fuel pressure was at 18psi with boost pump off. I looked everything over, confirmed I had freeflow of air through both vents, etc. I then unhooked the fuel line to the fuel pressure transducer, ran the boost pump and reconnected. I did the same with the main fuel supply line to the servo. Another test flight had pressures in the 17psi range with the boost pump off. When I went to full power to climb from 4000 to 6000, the pressure dropped again and I had to turn the boost pump on again. Pressure immediately went to 28. I'm stumped.
Rather than tear the whole system apart (not even knowing what I'm looking for), I'd like some ideas for a logical solution. Here's what's on my list for now:
Disassemble fuel filter in the AFP unit and examine/clean
Flow and pressure test each hose
Disconnect inlet line to engine pump, submerge in gas can and confirm pressure and flow of engine driven pump
And then??
If anyone has ideas, I'm all ears.
Thanks,
Bob
Rather than tear the whole system apart (not even knowing what I'm looking for), I'd like some ideas for a logical solution. Here's what's on my list for now:
Disassemble fuel filter in the AFP unit and examine/clean
Flow and pressure test each hose
Disconnect inlet line to engine pump, submerge in gas can and confirm pressure and flow of engine driven pump
And then??
If anyone has ideas, I'm all ears.
Thanks,
Bob