From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Fuel pressure trending lower.
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-1013277@logan.com>
Message-ID: <d0e14e84-f93f-251c-78ed-7537637bc046@verizon.net>
Date: Sun, 22 May 2022 20:44:36 -0400
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Thanks Steve.

 From your March/April 2017 posts it was a GSL392 that failed (high 
current draw/low pressure, even after you removed the insect you found 
in the inlet).

So this afternoon I ran the pump for about an hour. Amp draw from 3.04 
to 2.86 depending on voltage. Pressure between 43 and 40 psi (also 
depending on voltage). No noticeable degradation. Of course the 
difference with this test is that no fuel went to engine -- all 
recirculated through pressure regulator and back to tank. But no signs 
of a failing pump in terms of higher current draw and less pressure.

I guess I should put a temp probe on the pump and see what it reads 
during flight to see if that could be a factor.

Finn

On 5/21/2022 9:01 PM, Stephen Izett stephen.izett@gmail.com wrote:
> Hi Finn
>
> I had from memory a 393 fail. Can’t recall the symptoms sorry.
>
> I test before takeoff and then run both pumps below 2ooo ft incase of 
> failure.
> I plan to instal a comparator relay board in fuel pressure circuit to 
> automatically bring on backup pump and failure indicator.
> So testing before flight becomes - switch off and back on main engine 
> pump. This will save amps and wear of backup pump.
> When I switch off a pump at WOT the engine dies pretty much 
> instantaneously and don't want to be fiddling with a restart in the 
> Glasair which glides like a brick with the gear out in the breeze.
>
> Regards
> Steve Izett
>
>
>
>
>
>> On 21 May 2022, at 10:30 pm, Finn Lassen finn.lassen@verizon.net 
>> <mailto:finn.lassen@verizon.net> <flyrotary@lancaironline.net 
>> <mailto:flyrotary@lancaironline.net>> wrote:
>>
>> 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
>>
>


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    <div class="moz-cite-prefix">Thanks Steve.<br>
      <br>
      From your March/April 2017 posts it was a GSL392 that failed (high
      current draw/low pressure, even after you removed the insect you
      found in the inlet).<br>
      <br>
      So this afternoon I ran the pump for about an hour. Amp draw from
      3.04 to 2.86 depending on voltage. Pressure between 43 and 40 psi
      (also depending on voltage). No noticeable degradation. Of course
      the difference with this test is that no fuel went to engine --
      all recirculated through pressure regulator and back to tank. But
      no signs of a failing pump in terms of higher current draw and
      less pressure.<br>
      <br>
      I guess I should put a temp probe on the pump and see what it
      reads during flight to see if that could be a factor.<br>
      <br>
      Finn<br>
      <br>
      On 5/21/2022 9:01 PM, Stephen Izett <a class="moz-txt-link-abbreviated" href="mailto:stephen.izett@gmail.com">stephen.izett@gmail.com</a> wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:list-1013277@logan.com">
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
      Hi Finn
      <div class=""><br class="">
      </div>
      <div class="">I had from memory a 393 fail. Can’t recall the
        symptoms sorry.</div>
      <div class=""><br class="">
      </div>
      <div class="">I test before takeoff and then run both pumps below
        2ooo ft incase of failure.</div>
      <div class="">I plan to instal a comparator relay board in fuel
        pressure circuit to automatically bring on backup pump and
        failure indicator.</div>
      <div class="">So testing before flight becomes - switch off and
        back on main engine pump. This will save amps and wear of backup
        pump.</div>
      <div class="">When I switch off a pump at WOT the engine dies
        pretty much instantaneously and don't want to be fiddling with a
        restart in the Glasair which glides like a brick with the gear
        out in the breeze.</div>
      <div class=""><br class="">
      </div>
      <div class="">Regards  </div>
      <div class="">Steve Izett</div>
      <div class=""><br class="">
      </div>
      <div class=""><br class="">
      </div>
      <div class=""><br class="">
      </div>
      <div class=""><br class="">
        <div><br class="">
          <blockquote type="cite" class="">
            <div class="">On 21 May 2022, at 10:30 pm, Finn Lassen <a
                href="mailto:finn.lassen@verizon.net" class=""
                moz-do-not-send="true">finn.lassen@verizon.net</a> &lt;<a
                href="mailto:flyrotary@lancaironline.net" class=""
                moz-do-not-send="true">flyrotary@lancaironline.net</a>&gt;
              wrote:</div>
            <br class="Apple-interchange-newline">
            <div class="">
              <meta http-equiv="content-type" content="text/html;
                charset=utf-8" class="">
              <div text="#000000" bgcolor="#FFFFFF" class="">
                <p class="">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).</p>
                <p class="">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 <i class="">appeared</i>
                  to have changed. Nice to have engine logs from
                  practically each flight.<br class="">
                  <br class="">
                  But why? Pump getting weaker?</p>
                <p class="">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.</p>
                <p class="">My secondary (backup) pump is a GSL393. When
                  turning that on, fuel pressure comes back up to where
                  it needs to be.</p>
                <p class="">Anyone have experience with failing or weak
                  EFI pumps, particularly the GSL414?</p>
                <p class="">Finn<br class="">
                </p>
              </div>
            </div>
          </blockquote>
        </div>
        <br class="">
      </div>
    </blockquote>
    <p><br>
    </p>
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