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Do what yer' Momma said...
Go Play!
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Low fuel pressure - View Thread
My feel pressure keeps dropping to 1 psi during flight. Turning the boost pump on brings the pressure back up and after turning the boost pump off the pressure stays up, for a while. Engine is a carburated 0-360 A1A. Engine continues to operate normally at the low pressure, even during climb. Was wondering if any one else has had this problem and what may have solved it.
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Low fuel pressure - RE: - View Thread
Curious thing about the RV's and Lycoming fuel systems is the low pressures exhibited during enroute climbs, hot weather, and high altitudes. While I was testing my 7A, initially the weather was cool, but later on in the month we got some 80 deg. days. I noticed the fuel pressure dropped on the warmer days. Another test day I was cruising along and decided to climb to 8000 msl. As I climbed out enroute about 140 mph, the pressure dropped to near zero. I turned on the boost pump (something I never did on my Cherokee with the same engine) and the pressure returned to about 4.5 psi. Back on the ground the mechanical pump was now producing the 4.5 psi on it's own. I wondered if I developed some restriction to flow. I checked fuel flow and screens, all were fine. I called Van's and talked to Tom Green about it. He explained that the Lycoming is a good fuel pusher but a poor puller. The boost pump they provide and recommend is a better puller. He did say that the Lycoming pump would produce lower pressures at higher altitudes and warmer weather. He also reiterated that the Lycoming can operate at pressures between 0.5 psi and 8 psi. Also the higher angles of attack during climbs increases the height that the pump has to pull the fuel, reducing the available pressure. This all makes sense and, from personal experience, has not been a problem. If you are experiencing lower pressures at climbs of any angle or duration, turn on the boost pump. Cruising pressures on my carbureted 0-360 A1A have been steady at around 2 psi or better. These cruise altitudes are up to 13,000 msl. Hope this helps anyone experiencing fuel pressures that don't seem what they might expect. Tom tells me a lot of builders have seen these lower than usual numbers and as long as the 0.5 psi is maintained, it shouldn't be a problem. Turn on the boost pump during higher than normal fuel consumption modes like enroute climbs.
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| The "cover your butt" section |
This website was built to document my work on my RV-9A in
compliance with the FAA requirements needed to certify my aircraft. My experiences and comments are by
no means to be considered as instructions on how to build an RV-9A or any other aircraft.
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