lifendet Posted March 3, 2019 Report Posted March 3, 2019 Under Chp 28 IPC for my 77 M20J it redirects me to Chp 71-00-00 for the Engine Driven Pump but I can't seem to find it. IO-360-A3B6... Looking for a part #. My last flight it fluctuated from 25 then dropped to 14 psi at one point with no change in engine parameters or sound. After few seconds it shot back up to 24 but needle kept shaking. When I turned the electric pump on it shot to 26 psi and stayed there solid. Turned electric pump off it eventually settled to 24. Anything else I should be looking at? 20190302_141045.mp4
N201MKTurbo Posted March 3, 2019 Report Posted March 3, 2019 (edited) I would look at the fuel selector. Did you switch tanks when this happened? BTW, the pump is in the engine manual. Edited March 3, 2019 by N201MKTurbo 1
lifendet Posted March 3, 2019 Author Report Posted March 3, 2019 6 minutes ago, N201MKTurbo said: I would look at the fuel selector. Did you switch tanks when this happened? BTW, the pump is in the engine manual. That's the one thing I didn't do.. Will chk Engine Manual.
carusoam Posted March 3, 2019 Report Posted March 3, 2019 Fuel pressure oscillation is the most unsettling of all things... (PP opinion...) This is something to put in front of @M20Doc for input... Looks like the mechanical pump is being challenged to make pressure... it either is not producing enough pressure, or it could be leaking pressure that it built... It is good to see the electrical pump being able to do its job properly... Best regards, -a- 1
N201MKTurbo Posted March 3, 2019 Report Posted March 3, 2019 There can also be and air leak ahead of the pump, or cavitation ahead of the pump. There aren't many failure mechanisms that don't involve fuel dripping out of the fuel pump drain line.
Guest Posted March 3, 2019 Report Posted March 3, 2019 That fuel gauge looks like a direct mechanical gauge. Over time the air in the line (which acts to dampen pump pulses)from the fuel servo to the gauge is replaced by fuel. You can open the line at both ends and blow the fuel out then reconnect and see if it helps. As Rich points out air entry before the pump also happens, you can dribble a little 100 Wright oil down the fuel selector shaft to see if it temporarily seals the O ring. If it does help the O ring requires replacement. Clarence
Yetti Posted March 4, 2019 Report Posted March 4, 2019 Try a leakdown test. on the ground. elec pump on. open mixture. Count to 6 alligators. Mixture closed. elec pump off. If the pressures does not stay up for about a minute or so. Mechanical pump is bad. If you have fuel coming out of one of the three hoses in front of Pilot footwell. Your mechanical fuel pump is bad.
lifendet Posted March 4, 2019 Author Report Posted March 4, 2019 Try a leakdown test. on the ground. elec pump on. open mixture. Count to 6 alligators. Mixture closed. elec pump off. If the pressures does not stay up for about a minute or so. Mechanical pump is bad. If you have fuel coming out of one of the three hoses in front of Pilot footwell. Your mechanical fuel pump is bad. Will do and reportSent from my SM-G955U using Tapatalk
lifendet Posted March 5, 2019 Author Report Posted March 5, 2019 On 3/4/2019 at 9:36 AM, lifendet said: Will do and report Sent from my SM-G955U using Tapatalk No fuel out of hose front of Pilot footwell and pressure stayed for more than a min after electric pump was turned off. 1
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