speedbrakes22

Does anyone know what the nominal fuel flow should be for the electric boost pump?

One of the items on our suspect list is collapsing fuel hoses. We're going to remove them and check them more thoroughly, especiallly since replacement of all fuel lines forward of the firewall was done after the pre-purchase inspection. So if I understand correctly... 1) Boost pump and tank switch brings FF back to normal... Correct 2) we covered the usual fuel blockage and fuel leakage ares.. Yes, we did.. 3) pump operations must be next Okay, but why would tank switch make any difference? There's only one engine-drive pump and only one boost pump, both downstream of the tank selector valve. And what's the likelihood of a fuel pump failure being intermittent? We're planning a test that will measure the flow of each pump separately while the engine is running. 4) did we cover blocked tank vents? We've talked about vapor lock; investigation so far shows unobstructed fuels vents on the wings and the vent holes right near the filler cap. Are you thinking about something else?

Overhauled the servo and fuel flow divider. Checked and rechecked everything else and followed up on all suggestions from this thread and elsewhere. Went to pick the airplane and fly it back today, after 22 hours of driving. Ready to fly.. Put it through its paces on the ground 20+ minutes; purred like a Porsche. Shut it down; waited a half hour. Started right up; did several runups, some at full power; no problems. Took off stayed glued to vicinity of the airport for 45 minutes at 4,000 feet AGL; filipped tanks several times; toggled fueltboost pump on and off; various airspeeds and power settings; still Porsche-like. Felt like all was good and headed east. Then, without warning, and without any further adjustment in throttle mixture or prop, engine choked for 10 plus seconds and was about to quit. Enough altitude (4,000 AGL) to catch fuel pressure approacing zero; and fuel flow meter extremely low. Boost pump on, switched tanks and jockeyed throttle and mixture. Engine came back to life on other tank. Returned to overhead the airport; spent another 10 minutes trying to get the problem to repeat itself. No luck. Everything ran strong on both tanks. It's a wonderful airplane except for its engine quitting periodically, which significant impairs flight plans. Everyone is stumped. Any further ideas. .

Thanks, all the right cards fell into play for a successful outcome. We did have a few seconds to run diagnostics. The boost pump was on. Didn't have time to switch tanks. Didn't think to cycle the mags just verified they were on both. Did cycle the throttle and the engine sputtered momentarily then quit. The engine did run the following day, but wouldn't start again cold or hot. Vapor lock is a strong possibility since it was hot. Will inspect the ram air boot. Thanks

Great ideas, comments and suggestions. We are going to start with overhauling the fuel servo. It pasted bench test inspection but still weary about it because of its age. We have checked all the parts to the fuel system from the tanks to the injectors and found no problems.

Thanks for the welcoming! No engine monitor. The A&P checked the gascolator, no debris found. We will try the food jar test.

It's the IO-360 A1A. We will check the tank vents. Post incident test demonstrates good fuel flow to the servo. Not sure on pressure indication being we had very little time to set up forced landing.

Hello All We were 2-3 minutes from taking off in our Mooney M20E when the engine suddenly quit. It recovered briefly when the throttle was pulled back halfway, but then quit for good. Successful off-field landing; no injuries; no damage. Full tanks, both sumped 45 minutes after fueling. Full-power runup before takeoff revealed no anomalies. Fuel selector on left tank; boost pump on throughout the episode. Mixture rich. Field elevation 2,000 feet. Altitude when engine failed about 3,500 feet. Post-incident inspection shows good fuel flow from both tanks, good operation of fuel selector valve. Hoses from pump to servo secure, hose from servo to injection distributor secure. Only defect is missing full-rich stop on fuel injection servo. We’re having the servo rebuilt, but we’re not confident that’s the problem. Engine ran strong during prior 10hr X/C. Any ideas?