alpinelakespilot20
New Member
- Joined
- Jan 20, 2007
- Messages
- 27
The third flight of my RV-9 yesterday had to be cut short after 20 minutes due to erratic and high fuel pressure readings. I’ve read some previous fuel pressure threads that have provided some ideas--including the idea that the newer Kavlico type transducer might work better than the one originally shipped with my 2007 vintage D180--but perhaps I can provide a bit more detail that will help someone who knows more diagnose things a bit and give me a recommended place to start.
A bit of background that may or may not be relevant: this is only the 3rd flight since the plane first flew a couple weeks ago. It was the first flight since replacing the D180 (that failed during the plane’s second flight) with a replacement unit. Otherwise, the plane has flown very well on all flights with no apparent issues with fuel pressure. The manual that came with my carb’d O-320-D2A from Aerosport indicates acceptable fuel pressure range of 0.5-8.0 psi. Thus, my high yellow range is 7.0-8.0, with redline at 8.0 psi. The Dynon transducer is the 2 wire variety, one of which is a ground that goes back to the D180. And finally, FWIW, I checked to make sure I had the correct model transducer programmed into the D180, particularly since it was a new unit that I had just programmed.
Observation #1: On my third flight, about 10 minutes in and while leveling out at about 75% power, I started getting fuel pressure warnings on my D180, indicating that the fuel pressure was getting above 8.0 psi. It soon went into the red above 9.0, topping out at about 10.5. I tried turning the boost pump on and tried turning the boost pump off. Pressures soon dropped, with or without messing with the boost pump but a few seconds later the pressure would start to rise, again getting above 9.0. The chart below shows my psi’s and I’ve thrown in altitude as a reference just to show at what stage of the flight I was and to show that I was having issues at both high and low power settings, including once just as I was crossing the fence. As you can see, as soon as I started getting the high pressure warnings, I started a descent and landed.
Note: the flat altitudes at ~1700 ft show my time before takeoff and after landing. The total duration in flight was probably not more than 15 minutes.
Observation #2: Back in the hangar about 4 hours after shutdown, I turned on the Dynon. It showed 0.9 psi at rest. After turning on the boost pump, the fuel pressure rose right up to 10.6 psi (well into the red) and stayed there for at least 10 minutes, even after I turned the boost pump off.
Observation #3: Tried again in the hangar after about one hour later still. Turned on the Dynon and the boost pump brought the pressure up to 5.5psi where it stayed there for at least 20 minutes. Don’t know how long it stayed there total b/c I went home. (Even if the 5.5 psi is more normal in this case, the fact that I’ve got wildly different psi’s in each of my three observations, and very erratic readings in my first, suggests something’s funky.)
Anyway, do any of my observations lead to a particularly likely culprit? Would picking up one of the newer Kavlico pressure sensors be a good place to start? Even though the engine ran very well regardless of what the fuel pressure read, I’m not interested in flying again until I get it figured out.
Thanks in advance for any help.
A bit of background that may or may not be relevant: this is only the 3rd flight since the plane first flew a couple weeks ago. It was the first flight since replacing the D180 (that failed during the plane’s second flight) with a replacement unit. Otherwise, the plane has flown very well on all flights with no apparent issues with fuel pressure. The manual that came with my carb’d O-320-D2A from Aerosport indicates acceptable fuel pressure range of 0.5-8.0 psi. Thus, my high yellow range is 7.0-8.0, with redline at 8.0 psi. The Dynon transducer is the 2 wire variety, one of which is a ground that goes back to the D180. And finally, FWIW, I checked to make sure I had the correct model transducer programmed into the D180, particularly since it was a new unit that I had just programmed.
Observation #1: On my third flight, about 10 minutes in and while leveling out at about 75% power, I started getting fuel pressure warnings on my D180, indicating that the fuel pressure was getting above 8.0 psi. It soon went into the red above 9.0, topping out at about 10.5. I tried turning the boost pump on and tried turning the boost pump off. Pressures soon dropped, with or without messing with the boost pump but a few seconds later the pressure would start to rise, again getting above 9.0. The chart below shows my psi’s and I’ve thrown in altitude as a reference just to show at what stage of the flight I was and to show that I was having issues at both high and low power settings, including once just as I was crossing the fence. As you can see, as soon as I started getting the high pressure warnings, I started a descent and landed.
Note: the flat altitudes at ~1700 ft show my time before takeoff and after landing. The total duration in flight was probably not more than 15 minutes.
Observation #2: Back in the hangar about 4 hours after shutdown, I turned on the Dynon. It showed 0.9 psi at rest. After turning on the boost pump, the fuel pressure rose right up to 10.6 psi (well into the red) and stayed there for at least 10 minutes, even after I turned the boost pump off.
Observation #3: Tried again in the hangar after about one hour later still. Turned on the Dynon and the boost pump brought the pressure up to 5.5psi where it stayed there for at least 20 minutes. Don’t know how long it stayed there total b/c I went home. (Even if the 5.5 psi is more normal in this case, the fact that I’ve got wildly different psi’s in each of my three observations, and very erratic readings in my first, suggests something’s funky.)
Anyway, do any of my observations lead to a particularly likely culprit? Would picking up one of the newer Kavlico pressure sensors be a good place to start? Even though the engine ran very well regardless of what the fuel pressure read, I’m not interested in flying again until I get it figured out.
Thanks in advance for any help.