Problem Found !!!! Strange fuel pressure drop issue
I flew the RV-9A(mechanical fuel injection) to Savannah this morning and after about 30 minutes of flying noticed the RPM fluctuating somewhat. I noticed that the fuel pressure was also varying and turned on the boost pump. Pressure came back up to 30 psi. Turned the boost pump back off and the fuel pressure dropped a bit and it was variable. Fuel flow reduced whenever fuel pressure got to 20 psi or so, Boost pump back on and all is good. I left it on for 5 or 10 minutes. Turned it off, Same drop in fuel pressure. Changed tanks, and same symptoms. This went on for another maybe 10 minutes then when I turned the boost pump off, the fuel pressure dropped to 26 psi and stayed there for the rest of the flight, No varying. I left Savannah and returned home late morning and all was good until I turned off the boost pump. Pressure started varying all over again just like before. After about 45 minutes of playing with the boost on, boost off, I turned off the boost and like before, the fuel pressure went to 26 psi and stayed there. No change in throttle position or altitude or mixture strength affected these symptoms.
Any words of wisdom?
Ed
I flew the RV-9A(mechanical fuel injection) to Savannah this morning and after about 30 minutes of flying noticed the RPM fluctuating somewhat. I noticed that the fuel pressure was also varying and turned on the boost pump. Pressure came back up to 30 psi. Turned the boost pump back off and the fuel pressure dropped a bit and it was variable. Fuel flow reduced whenever fuel pressure got to 20 psi or so, Boost pump back on and all is good. I left it on for 5 or 10 minutes. Turned it off, Same drop in fuel pressure. Changed tanks, and same symptoms. This went on for another maybe 10 minutes then when I turned the boost pump off, the fuel pressure dropped to 26 psi and stayed there for the rest of the flight, No varying. I left Savannah and returned home late morning and all was good until I turned off the boost pump. Pressure started varying all over again just like before. After about 45 minutes of playing with the boost on, boost off, I turned off the boost and like before, the fuel pressure went to 26 psi and stayed there. No change in throttle position or altitude or mixture strength affected these symptoms.
Any words of wisdom?
Ed
Last edited: