Adding a data point on this.
I have about 900h on my RV-8 with a Lyc IO360M1B, which was installed new with the airplane. Nine months ago, I upgraded my panel to dual G3x's from, among other things, the Grand Rapids EIS system.
At about the time that I was testing out my new avionics, I noticed occasional fluctuations in fuel pressure, from a baseline of about 24psi to momentary lows as much as 14-15psi. The dips were transient, occurring maybe once or twice per hour, and not associated with any changes in engine output, RPM/MP, or sound/tone. They seemed to happen at higher altitudes during prolonged cruise (6-9000'), but were not associated with temperature. There were no changes in fuel flow. Activating the Aux Fuel Pump remedied the low pressure without hesitation or fail. It is possible that this was occurring with the EIS system and that I missed it.
I decided to have the fuel pump replaced before it failed outright. Upon removal, there was nothing out of the ordinary; no debris, no leaks, no undue chaffing or obvious wear. I did not take the pump apart to inspect the diaphragm.
The new pump is generating 32-34psi consistently, hence confirming (to me at least) that the original pump was in slow failure mode.
I was under the impression that these pumps rarely fail.
Hope this helps someone in the future.
Jon Weiswasser
N898JW, RV-8
IO360M1B
I have about 900h on my RV-8 with a Lyc IO360M1B, which was installed new with the airplane. Nine months ago, I upgraded my panel to dual G3x's from, among other things, the Grand Rapids EIS system.
At about the time that I was testing out my new avionics, I noticed occasional fluctuations in fuel pressure, from a baseline of about 24psi to momentary lows as much as 14-15psi. The dips were transient, occurring maybe once or twice per hour, and not associated with any changes in engine output, RPM/MP, or sound/tone. They seemed to happen at higher altitudes during prolonged cruise (6-9000'), but were not associated with temperature. There were no changes in fuel flow. Activating the Aux Fuel Pump remedied the low pressure without hesitation or fail. It is possible that this was occurring with the EIS system and that I missed it.
I decided to have the fuel pump replaced before it failed outright. Upon removal, there was nothing out of the ordinary; no debris, no leaks, no undue chaffing or obvious wear. I did not take the pump apart to inspect the diaphragm.
The new pump is generating 32-34psi consistently, hence confirming (to me at least) that the original pump was in slow failure mode.
I was under the impression that these pumps rarely fail.
Hope this helps someone in the future.
Jon Weiswasser
N898JW, RV-8
IO360M1B