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Hermes SMTP Server) with ESMTPA ID d0f25ee241a38d0fcd730642161a49ef; Sat, 21 May 2022 22:20:43 +0000 (UTC) Subject: Re: [FlyRotary] Re: Fuel pressure trending lower. To: Rotary motors in aircraft References: Message-ID: <7922e624-9ff0-8461-7dd1-6d7d7c92417b@verizon.net> Date: Sat, 21 May 2022 18:20:39 -0400 User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------A60CA4630E739ECFAD6E1908" Content-Language: en-US X-Antivirus: Avast (VPS 220521-6, 05/21/2022), Outbound message X-Antivirus-Status: Clean X-Mailer: WebService/1.1.20225 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.aol Content-Length: 14570 This is a multi-part message in MIME format. --------------A60CA4630E739ECFAD6E1908 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit After maybe less than 75 hours in use? Recently, during annual, I discovered I'd installed the pre-pumps filter the wrong way. Tried to clean the cartridge real well, but not impossible that some junk hidden under the edges could have gotten into the main pump input as I'm only running the backup pump for a few seconds during pre-flight checks. Actually that doesn't explain the long term decline. So back to the pump failing. Dang! But why full pressure when cold and then gradually dropping during flight (dropping more recently). It's my understanding that the Walbro EFI pumps do not have check valves but acts as a valve when turned off. Thus no fuel off-valve in my RV-4. Now I'm wondering if this is happening to others but just not visible when using the higher capacity GSL393, 392 or 391 pumps. They would have to degrade to below the fuel regulator setting before becoming noticeable. For some reason the GSL393 is cheaper than the GSL414. Finn On 5/21/2022 5:58 PM, 12348ung@gmail.com wrote: > > Finn, > >             Once again the blind leading the blind, but it appears > that wear and old age has gotten to your pump.  I suspect that as with > the second pump all is normal, then that excludes filter and water > etc, just needs a replacement pump IMHO. > >                 Easy when it is your money! > > Neil. > > *From:* Rotary motors in aircraft > *Sent:* Sunday, May 22, 2022 2:14 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Fuel pressure trending lower. > > Do EFI pumps have an internal check valve? Dirty fuel filter? > > Bobby > > Get Outlook for iOS > > ------------------------------------------------------------------------ > > *From:*Rotary motors in aircraft > on behalf of Finn Lassen > finn.lassen@verizon.net > > > *Sent:* Saturday, May 21, 2022 9:30:30 AM > *To:* Rotary motors in aircraft > > *Subject:* [FlyRotary] Fuel pressure trending lower. > > Recently I noticed my fuel pressure being low. Noticed because engine > did not come up in power when advancing to full throttle. Noticed > mixture real lean. Checking fuel pressure as low as 28 psi (normally > 35 and up to 40 at full throttle). > > Going over my engine logs since first flight I now see that fuel > pressure has been trending lower through each flight -- more > pronounced on longer flights (40+ minutes). More and more pronounced > over the months and became really noticeable over last month. Could > explain why mixture tuning /appeared/ to have changed. Nice to have > engine logs from practically each flight. > > But why? Pump getting weaker? > > My primary fuel pump is a GSL414. I figured it was wasted energy to > push way more fuel than needed through the pressure regulator back to > the tank. > > My secondary (backup) pump is a GSL393. When turning that on, fuel > pressure comes back up to where it needs to be. > > Anyone have experience with failing or weak EFI pumps, particularly > the GSL414? > > Finn > > *Disclaimer* > > The information contained in this communication from the sender is > confidential. It is intended solely for use by the recipient and > others authorized to receive it. If you are not the recipient, you are > hereby notified that any disclosure, copying, distribution or taking > action in relation of the contents of this information is strictly > prohibited and may be unlawful. > > This email has been scanned for viruses and malware, and may have been > automatically archived by *Mimecast Ltd*, an innovator in Software as > a Service (SaaS) for business. Providing a *safer* and *more useful* > place for your human generated data. Specializing in; Security, > archiving and compliance. To find out more Click Here > > --------------A60CA4630E739ECFAD6E1908 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
After maybe less than 75 hours in use?

Recently, during annual, I discovered I'd installed the pre-pumps filter the wrong way. Tried to clean the cartridge real well, but not impossible that some junk hidden under the edges could have gotten into the main pump input as I'm only running the backup pump for a few seconds during pre-flight checks. Actually that doesn't explain the long term decline. So back to the pump failing. Dang! But why full pressure when cold and then gradually dropping during flight (dropping more recently).

It's my understanding that the Walbro EFI pumps do not have check valves but acts as a valve when turned off. Thus no fuel off-valve in my RV-4.

Now I'm wondering if this is happening to others but just not visible when using the higher capacity GSL393, 392 or 391 pumps. They would have to degrade to below the fuel regulator setting before becoming noticeable.

For some reason the GSL393 is cheaper than the GSL414.

Finn
 
On 5/21/2022 5:58 PM, 12348ung@gmail.com wrote:

Finn,

            Once again the blind leading the blind, but it appears that wear and old age has gotten to your pump.  I suspect that as with the second pump all is normal, then that excludes filter and water etc, just needs a replacement pump IMHO.

                Easy when it is your money!

Neil.

            

 

From: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sunday, May 22, 2022 2:14 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Fuel pressure trending lower.

 

Do EFI pumps have an internal check valve? Dirty fuel filter?  

 

Bobby

From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Sent: Saturday, May 21, 2022 9:30:30 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Fuel pressure trending lower.

 

Recently I noticed my fuel pressure being low. Noticed because engine did not come up in power when advancing to full throttle. Noticed mixture real lean. Checking fuel pressure as low as 28 psi (normally 35 and up to 40 at full throttle).

Going over my engine logs since first flight I now see that fuel pressure has been trending lower through each flight -- more pronounced on longer flights (40+ minutes). More and more pronounced over the months and became really noticeable over last month. Could explain why mixture tuning appeared to have changed. Nice to have engine logs from practically each flight.

But why? Pump getting weaker?

My primary fuel pump is a GSL414. I figured it was wasted energy to push way more fuel than needed through the pressure regulator back to the tank.

My secondary (backup) pump is a GSL393. When turning that on, fuel pressure comes back up to where it needs to be.

Anyone have experience with failing or weak EFI pumps, particularly the GSL414?

Finn

 

Disclaimer

The information contained in this communication from the sender is confidential. It is intended solely for use by the recipient and others authorized to receive it. If you are not the recipient, you are hereby notified that any disclosure, copying, distribution or taking action in relation of the contents of this information is strictly prohibited and may be unlawful.

This email has been scanned for viruses and malware, and may have been automatically archived by Mimecast Ltd, an innovator in Software as a Service (SaaS) for business. Providing a safer and more useful place for your human generated data. Specializing in; Security, archiving and compliance. To find out more Click Here


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