hammdo Posted March 4, 2023 Report Posted March 4, 2023 Cancelled a flight today due to a ‘new’ sound that only happens when the electric fuel pump comes on. Pressure is great but I’ve never heard this noise before. Thoughts? -Don Quote
takair Posted March 4, 2023 Report Posted March 4, 2023 Was the fuel selector on? They will definitely sound different when not wet. Assuming it was on, I would guess the bearings are starting to go. Last year my Weldon pump gradually changed tone, then went intermittent, then seized…..but over a long period of time. In hindsight I should have been more proactive. As I recall, the Dukes prior to that also took many months of hinting before it failed. I suspect you could safely fly it to get it to maintenance, may even go another 6 months. If it is dripping fuel, that is another story. That means the seal is also gone and as you know, mixing fuel and sparks is not good. Quote
hammdo Posted March 4, 2023 Author Report Posted March 4, 2023 Selector was on, and I did switch tanks left to right. Selector valve was OH by Maxwells. Was fine last weekend. I may try and run it tomorrow to see if it just needs to prime more. Maybe start it up first and double check. Thanks! -Don Quote
Hank Posted March 4, 2023 Report Posted March 4, 2023 1 hour ago, hammdo said: Selector was on, and I did switch tanks left to right. Selector valve was OH by Maxwells. Was fine last weekend. I may try and run it tomorrow to see if it just needs to prime more. Maybe start it up first and double check. Thanks! -Don You don't run the pump before cranking? I run mine until fuel pressure stabilizes, turn it off then turn the key. When it's cold out, I'll pause to wind & set the clock and adjust my headset, then crank. Quote
Guest Posted March 4, 2023 Report Posted March 4, 2023 4 hours ago, hammdo said: Cancelled a flight today due to a ‘new’ sound that only happens when the electric fuel pump comes on. Pressure is great but I’ve never heard this noise before. Thoughts? -Don Time for a visit with www.Aeromotorsllc.com Quote
hammdo Posted March 4, 2023 Author Report Posted March 4, 2023 Always before cranking -- I do that as part of the first step -- pump on, check pressure, check fuel gauges. Its when I first turned it on during pre-flight I heard the noise. Didn't get very far once I heard that. Don Maxwell said sometimes air gets in and suggested I start it with the mechanical pump to do a purge -- then see if she is still making noise. Pump shows 6-7 PSI when she started up... Gonna see if that helps it tomorrow... -Don 2 Quote
hammdo Posted March 4, 2023 Author Report Posted March 4, 2023 1 minute ago, M20Doc said: Time for a visit with www.Aeromotorsllc.com That is what I figured.... Thus grounded the plane... -Don Quote
takair Posted March 4, 2023 Report Posted March 4, 2023 1 hour ago, hammdo said: Always before cranking -- I do that as part of the first step -- pump on, check pressure, check fuel gauges. Its when I first turned it on during pre-flight I heard the noise. Didn't get very far once I heard that. Don Maxwell said somethings air gets in and suggested I start it with the mechanical pump to do a purge -- then see if she is still making noise. Pump shows 6-7 PSI when she started up... Gonna see if that helps it tomorrow... -Don Maxwell’s advice is a good idea. Try starting like normal, run for a few minutes, shut down and listen to the pump again. It does sound a little like when a pump has some air. On a fuel injected engine, there is a slight change in tone when mixture is pushed forward and it also helps clear any air. On carbureted engine, the only way I can see to clear air is to get flow through the carb, and that requires running it. If you had recent work done on the fuel system, it seems possible to have air in the lines, or perhaps even a leak, such that it is pulling air. Quote
hammdo Posted March 5, 2023 Author Report Posted March 5, 2023 Yep, had the fuel flow transducer done - have about 6 hours on it since then… Gonna confirm tomorrow… -Don Quote
Ragsf15e Posted March 5, 2023 Report Posted March 5, 2023 2 minutes ago, hammdo said: Yep, had the fuel flow transducer done - have about 6 hours on it since then… Gonna confirm tomorrow… -Don Maybe I’m not smart, but if it makes pressure and isn’t leaking, I might just keep using it. 2 Quote
Hank Posted March 5, 2023 Report Posted March 5, 2023 1 hour ago, hammdo said: Don Maxwell said somethings air gets in and suggested I start it with the mechanical pump to do a purge -- then see if she is still making noise. Pump shows 6-7 PSI when she started up... Gonna see if that helps it tomorrow... -Don 6 psi is our max pressure. I typically see ~6.5 when it stops rising. If it's been a while, it's really loud, then quietens up once fuel is flowing and pressure starts to build. Never hurts to have someone look at it when the behavior changes. 1 Quote
PT20J Posted March 5, 2023 Report Posted March 5, 2023 17 minutes ago, Ragsf15e said: Maybe I’m not smart, but if it makes pressure and isn’t leaking, I might just keep using it. Interesting -- I happened to drop by the Weldon booth at the Northwest Aviation Conference last weekend and asked what the common failure modes were. The rep said the seals (which will cause a leak out the drain hole) and the brushes in the motor. I asked specifically about the bearings and impeller and he said that the bearings are usually not a problem and the impeller is hardened steel and doesn't really wear. He said as long as they aren't leaking and make pressure, they are good. If it were mine, I wouldn't do anything just because it made a noise once. I'd keep an eye on it for awhile. Skip 1 Quote
hammdo Posted March 5, 2023 Author Report Posted March 5, 2023 Good to know, I have no leaks and it makes normal pressure. I’m of the mindset that anything out of ‘normal’ ops, I need to verify. I keep track of every flights ops so I can notice trends like this. Better to verify on the ground and make sure… The noise right now is constant - every time I turn it off/on. I’ll do a start and shutdown to see if it still does it tomorrow… -Don Quote
N201MKTurbo Posted March 5, 2023 Report Posted March 5, 2023 The Weldon pump makes a lot more noise than the Dukes. Is it possible that you have never heard it before without the engine running? 1 Quote
hammdo Posted March 5, 2023 Author Report Posted March 5, 2023 No, I do a boost pump as my first step of pre-flight. I turn it on, listen for any anomalies and, if none, check the pressure and fuel gauges. Today, I heard the noise for the first time (sat a week as I fly weekly). Ran it several times (never started the engine). It’s just odd as I’ve never heard it since I’ve owned it. -Don Quote
takair Posted March 5, 2023 Report Posted March 5, 2023 1 hour ago, PT20J said: Interesting -- I happened to drop by the Weldon booth at the Northwest Aviation Conference last weekend and asked what the common failure modes were. The rep said the seals (which will cause a leak out the drain hole) and the brushes in the motor. I asked specifically about the bearings and impeller and he said that the bearings are usually not a problem and the impeller is hardened steel and doesn't really wear. He said as long as they aren't leaking and make pressure, they are good. If it were mine, I wouldn't do anything just because it made a noise once. I'd keep an eye on it for awhile. Skip My Weldon pump had bearing seize last year. The seal was leaking, not enough to dribble, but enough to dry out the bearing, which eventually came apart and seized. I was surprised that it didn’t show any hint of leaking, but it definitely started to sound funny before failure. I still need to get it repaired. Has a unique seal arrangement. It was faster to get my old Dukes pump repaired by Aeromotors. In my case, the Dukes pump is louder than the Weldon….even when it was failing, has different sound as well. 1 Quote
47U Posted March 5, 2023 Report Posted March 5, 2023 11 hours ago, hammdo said: Thoughts? How old is the pump? You did pull the panel when you looked for leaks and did a general inspection of the installation? If it is air in the line, and an engine run cures the noise, then you should inspect all the hard lines and hoses for condition. It’s possible to have a cracked tube (maybe at the flare-nut sleeve) or hose inner-liner fail to the point they suck air, but do not leak externally. Erratic fuel pressure and flow could also be an indication of air in the fuel line. I think you’re right, though. If the pump is old (10 years or more) and it’s making noise which it didn’t make before, I’d lean towards overhaul / replacement if you can’t find anything else wrong. Quote
hammdo Posted March 5, 2023 Author Report Posted March 5, 2023 32 years since last OH (5/91), I checked the logs. New lines for the fuel flow transducer. No leaks I checked the install. I’ll check again tomorrow… Fuel preassure is the same as always - just louder noise from running the pump… -Don Quote
M20F-1968 Posted March 5, 2023 Report Posted March 5, 2023 Make sure the mixture is fully forward. The pump is likely is dry. Bearings do not go bad in 1 week. John Breda 1 Quote
47U Posted March 5, 2023 Report Posted March 5, 2023 14 hours ago, hammdo said: 32 years since last OH (5/91) 32 years is a long time. If your engine-driven pump craps out (when was IT last overhauled), are you going trust that electric noise-maker in continuous duty for 30 or 45 minutes to get you safely on the ground? I think it’s talking to you. It might fail in the next 5 minutes, or the next 500 minutes. You run the electric fuel pump only for critical phases of flight, primarily take off and landing, a few minutes at a time. Continuous duty, listening to that noise, would give me some serious pucker factor. 1 Quote
PT20J Posted March 5, 2023 Report Posted March 5, 2023 I listened to it again. It sounds like it might just be running dry for some reason. I might try starting and running the engine for a few minutes to make sure that all the lines are full of fuel an then shut down and listen to it again. 1 Quote
hammdo Posted March 5, 2023 Author Report Posted March 5, 2023 She's leaking -- went to the hanger today and found the blue stain on the floor (was not there yesterday). Flew it for an hour and a half and the noise never went away. I'm guessing internal seal since I saw fuel stain on the floor and the tube is wet: She's going for overhaul... -Don 1 2 Quote
hammdo Posted March 6, 2023 Author Report Posted March 6, 2023 Anyone know what AN fuel washers these are? -Don Quote
47U Posted March 6, 2023 Report Posted March 6, 2023 1 hour ago, hammdo said: Anyone know what AN fuel washers these are? The ‘68 IPB says an AN6291-6, and I’d bet you have the same size fittings. 1 Quote
hammdo Posted March 6, 2023 Author Report Posted March 6, 2023 Yep a 9/16th strat-o-seal should work also but I’d rather have the right part… -Don Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.