Fuel Pump Death Knell??

[Ragsf15e]

I’ve been slowly troubleshooting a fluctuating fuel glow issue, so I’m hypersensitive to the fuel system right now.  This is a Weldon 8163-A 14V pump.  I ran it today after flying to check the pressure without the engine running.  Mixture and throttle mid rangr, so obviously fuel was flowing (and now my sniffle valve is also checked).  Pressure was steady at 24psi, but it sounds bad to me.  It doesn’t leak though.  Last replaced about 18 years ago.  
Am I crazy for thinking of OHing the fuel pump because it sounds bad?

Turn up volume for best results…

https://photos.app.goo.gl/35kJCRQrkTy1HKDy6

[Utah20Gflyer]

If my fuel pump sounded like that I would get it overhauled.  Not a mechanic but that doesn't sound right.  At least mine doesn't sound anything like that.  Can't think of anything external to the pump that would cause it to sound like so I would assume it's some sort of internal issue.  Maybe someone more informed will chime in.  

[carusoam]

If the sound has changed… over the years…

Time to get a better look at its insides….

 

Some devices are noisy from the beginning…

But a change in sound would be different…

PP thoughts only, not a mechanic…

Best regards,

-a-

[PT20J]

It sounds a lot like mine which is a A8163-B (same pump, 24V motor) except for the rhythmic wavering. Are you sure the pressure was steady? In an earlier post you did a similar test that showed pressure fluctuations. I was wondering if the sound tracks the pressure.

[Yetti]

To check the electric pump....    When you turn the pump on or off in with the engine running there should be a slight increase or decrease if fuel pressure.   So at least twice per flight you will check the pump.

[Marauder]

I’ve been slowly troubleshooting a fluctuating fuel glow issue, so I’m hypersensitive to the fuel system right now.  This is a Weldon 8163-A 14V pump.  I ran it today after flying to check the pressure without the engine running.  Mixture and throttle mid rangr, so obviously fuel was flowing (and now my sniffle valve is also checked).  Pressure was steady at 24psi, but it sounds bad to me.  It doesn’t leak though.  Last replaced about 18 years ago.  
Am I crazy for thinking of OHing the fuel pump because it sounds bad?
Turn up volume for best results…
https://photos.app.goo.gl/35kJCRQrkTy1HKDy6

I have the same aux pump. Mine doesn’t sound cyclic like that.


Sent from my iPhone using Tapatalk Pro

[Ragsf15e]

15 minutes ago, Marauder said:

I have the same aux pump. Mine doesn’t sound cyclic like that.


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Thanks.  I’m probably being too jumpy with it, but it doesn’t sound good to me. It’s pretty old too.  I’m usually of the opinion that you shouldn’t fix it if it ain’t broke.  After running it with steady pressure, I don’t think it’s connected to my jumpy fuel pressure but it might strand me somewhere this summer.

[carusoam]

Just now, Ragsf15e said:

Thanks.  I’m probably being too jumpy with it, but it doesn’t sound good to me. It’s pretty old too.  I’m usually of the opinion that you shouldn’t fix it if it ain’t broke.  After running it with steady pressure, I don’t think it’s connected to my jumpy fuel pressure but it might strand me somewhere this summer.

If it ain’t broke… is solid thinking….

 

If it is making strange noises, and has a history of jumpy fuel pressure…

It is hobbling towards the could be broke and will let you know at an inconvenient time…. 

Bummer, I couldn’t get the sound to come up on my iPad….

Best regards,

-a-

[Ragsf15e]

1 hour ago, PT20J said:

It sounds a lot like mine which is a A8163-B (same pump, 24V motor) except for the rhythmic wavering. Are you sure the pressure was steady? In an earlier post you did a similar test that showed pressure fluctuations. I was wondering if the sound tracks the pressure.

Yeah I let it run this time for about 15” instead of just a quick prime.  It got up to 24psi and held it pretty solid.  I was actually hoping it would be jumping around.

[Ragsf15e]

1 hour ago, Yetti said:

To check the electric pump....    When you turn the pump on or off in with the engine running there should be a slight increase or decrease if fuel pressure.   So at least twice per flight you will check the pump.

The mech fuel pump on mine seems to be higher , close to 30psi, where the electric is at 24.  My fuel pressure is pretty jumpy, and there isn’t really an change in psi when I turn it on/off with the engine running.

[N201MKTurbo]

The pump has a built in pressure regulator that bypasses fuel around the pump if it exceeds the set pressure. This is required for a positive displacement pump. So even if the pump was turning erratically, the pressure would still be steady.

[A64Pilot]

I wonder if the cycling is maybe due voltage fluctuations, like maybe the strobes or something is on?

[cferr59]

Like others, my Dukes sounds like that minus the wobbling. I always thought its sound was not confidence inspiring, but there was no obvious problem. One day, it started dripping at the weep hole so I had it overhauled by Aeromotors.  It still sounds exactly the same.

[RobertGary1]

16 hours ago, Yetti said:

To check the electric pump....    When you turn the pump on or off in with the engine running there should be a slight increase or decrease if fuel pressure.   So at least twice per flight you will check the pump.

Unless you’re mechanical pump is new. My factory new engine came from Lycoming at the top of the green with just the mechanical pump so no room to go up more with the electric pump. But you can test that at start up. 

[PT20J]

15 hours ago, Ragsf15e said:

Yeah I let it run this time for about 15” instead of just a quick prime.  It got up to 24psi and held it pretty solid.  I was actually hoping it would be jumping around.

Let’s see if I have this right:

When the engine is running, the fuel pressure randomly wanders up and down by a couple of psi. Turning on the boost pump does not affect the wandering.

With the engine stopped, the boost pump puts out steady pressure (no wandering) with the mixture in ICO or rich. 

The boost pump sounds normal except for a rhythmic fluctuation in sound but without any pressure or flow variation.

Did I get that right?

If you run the boost pump with the engine running, does it make the same rhythmic sound?

Skip

[201Mooniac]

I have the same pump, it just recently (last month) started sounding like that, was mostly quiet without the periodic pulses.  I was at my shop this morning and I forgot to mention it and after they did a run up they said hey, sounds like your boost pump is on its last legs.  Luckily they are fairly available.

[Ragsf15e]

2 hours ago, PT20J said:

Let’s see if I have this right:

When the engine is running, the fuel pressure randomly wanders up and down by a couple of psi. Turning on the boost pump does not affect the wandering.

With the engine stopped, the boost pump puts out steady pressure (no wandering) with the mixture in ICO or rich. 

The boost pump sounds normal except for a rhythmic fluctuation in sound but without any pressure or flow variation.

Did I get that right?

If you run the boost pump with the engine running, does it make the same rhythmic sound?

Skip

First part yes, but more than a couple psi.  It’s pretty random, but say 17-31psi.  Seems higher on takeoff power, but not largely different.  Boost pump has no effect.

Yes.  I ran the BP with mixture mid range and it achieved and held 24psi as fuel flowed.  No fluctuating.

Yes, boost pump sounds normal except for the rhythmic part but pressure didn’t seem to fluctuate.

I haven’t tried to listen to the BP with the engine running, but Ill try it next time out.  I wonder if I’ll be able to hear it?  I’ll also download the newest pressure fluctuations in the different conditions.

Thanks for helping get my story straight!

 

[PT20J]

28 minutes ago, Ragsf15e said:

First part yes, but more than a couple psi.  It’s pretty random, but say 17-31psi.  Seems higher on takeoff power, but not largely different.  Boost pump has no effect.

Yes.  I ran the BP with mixture mid range and it achieved and held 24psi as fuel flowed.  No fluctuating.

Yes, boost pump sounds normal except for the rhythmic part but pressure didn’t seem to fluctuate.

I haven’t tried to listen to the BP with the engine running, but Ill try it next time out.  I wonder if I’ll be able to hear it?  I’ll also download the newest pressure fluctuations in the different conditions.

Thanks for helping get my story straight!

 

I can hear my boost pump with the engine running at low power on the ground since it is right under my feet.

My first thought about the rhythmic sound would be the pressure regulator within the pump, but since the fuel pressure is constant that doesn't seem likely. Second thought is that something is causing the the motor speed to vary. The variation is slow enough that the pressure regulator should keep the pressure constant. It might be interesting to watch the ammeter and see if it wavers in time with the pump sound. I doubt that it is air or pump cavitation as I would think that would be more random.

Skip

[laytonl]

A trip to Aeromotors will fix that noise.  Lee