brad Posted October 28, 2015 Report Posted October 28, 2015 After overhaul, I've had an ongoing issue. Above 10,000, the fuel flow drops from 24 to 17 every 40-50 seconds. Still in green arch. Boost pump cures. Have had all fuel components rechecked by appropriate manufacturers. Works fine below 10,000. 1975 F. First purchased in 2002. Really strange. Any thoughts? Excellent overhaul by Eagle engines - 220 hours. Quote
mike_elliott Posted October 28, 2015 Report Posted October 28, 2015 After overhaul, I've had an ongoing issue. Above 10,000, the fuel flow drops from 24 to 17 every 40-50 seconds. Still in green arch. Boost pump cures. Have had all fuel components rechecked by appropriate manufacturers. Works fine below 10,000. 1975 F. First purchased in 2002. Really strange. Any thoughts? Excellent overhaul by Eagle engines - 220 hours. Yep, you probably have a small hole in the mechanical pump's diaphragm. My F did that at 8000' DA, new mechanical pump cured it. Change it yourself under adult A$P supervision and you will have the bonus of learning all sorts of new vulgarities. Bottom line, get it fixed before it makes you show how great of a glider pilot you are. Quote
takair Posted October 28, 2015 Report Posted October 28, 2015 A friend recently described similar symptoms and it turned out to be a small leak in the gaskolator gasket. It was such that no fuel came out and it would only happen in flight. Quote
brad Posted October 29, 2015 Author Report Posted October 29, 2015 Thanks. Mechanical pump on the way. Quote
N201MKTurbo Posted October 29, 2015 Report Posted October 29, 2015 My vote is the fuel selector. Have you tried switching tanks when this happens? Quote
carusoam Posted October 29, 2015 Report Posted October 29, 2015 Are are you guys collectively describing the effect of air bubbles in the FF sensor? If this is the case, all seals in the fuel system are suspect. Both fuel pumps have drains that can be checked for footprints from a diaphragm leak. Altitude will increase the size of any bubbles that are in the system. In some cases flushing them out. Either way, bubbles are a challenge for fuel distribution. Good luck with getting to the cause quickly. Remember to have your mechanic inspect the old pump for the proof you need to be sure it is the problem. (Sounds like you may have done this already) Best regards, -a- Quote
Guest Posted October 29, 2015 Report Posted October 29, 2015 Flow or pressure? 24gph would be high for your F model Clarence Quote
Andy95W Posted October 30, 2015 Report Posted October 30, 2015 Any other change than the indication? EGT? CHT? Engine roughness? A change that significant should present itself in multiple ways. FF change only would definitely make the indication suspect. Quote
brad Posted November 2, 2015 Author Report Posted November 2, 2015 All - Fuel pressure drops and goes right back up. No other indications of any kind. Boost pump cures. Only above 10,000. I'm counting on the new engine driven fuel pump curing - ordered. Quote
Joe Larussa Posted November 17, 2015 Report Posted November 17, 2015 On November 2, 2015 at 12:21:06 PM, brad said: All - Fuel pressure drops and goes right back up. No other indications of any kind. Boost pump cures. Only above 10,000. I'm counting on the new engine driven fuel pump curing - ordered. Did the new pump fix the problem? Quote
brad Posted November 21, 2015 Author Report Posted November 21, 2015 Factory new engine driven pump installed today. Set up cruise at 12.5. Worked perfectly! Problem finally solved. Quote
carusoam Posted November 21, 2015 Report Posted November 21, 2015 Great follow-up! Was there any post mortum done on the old pump? A picture of a broken diaphragm would explain what happened to it. Best regards, -a- Quote
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