REFLECTOR:Fuel filters

John Dibble reflector@tvbf.org
Tue, 17 Feb 2004 12:45:16 -0600


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That's a nice setup.  When I bought my Velocity it had 205 hours and no 
filter, so I doubt that a little unfiltered fuel is going to be a big 
problem.  I did have an occasional slow fuel leak at the carbureator (I 
could "fix" it by shutting off the fuel and running the engine until the 
bowl was empty - on the ground of course.)  My guess is that the float 
valve was dirty and not sealing well.  I just replaced the float valve 
and seat so soon I will know it that was the problem.  The bowl and 
valve were very clean with no sediment.

John

Brian Michalk wrote:

> I'm sure something like that exists, but would you want unfiltered 
> fuel plugging up your system?
> There are commercial filters that have a sensor that tells you when 
> the filter is plugged, but you could roll one yourself by putting a 
> pressure sensor on each side of the filter.  As the filter becomes 
> clogged, the pressure across the filter increases, showing up as a 
> delta voltage on your sensors.
>  
> I've gone perhaps a little overboard instrumenting my airplane ... I 
> do instrumentation for a living.  I've got sensors at each fuel pump 
> output ... I'll draw a picture.  It's easier.
>  
>  
> EFP-->PS1-->CV-->FILT
>                      \
>                       TEE-->PS3-->flow1-->FPR-->flow2-->PS4-->engine
>                      /
> MFP-->PS2-->CV-->FILT
>  
> EFP-electric driven fuel pump
> MFP-mechanical driven fuel pump
> PS1-pressure from electric fuel pump
> PS2-pressure from mechanical fuel pump
> FILT-fuel filters
> CV-check valve
> PS3-pressure at input of fuel pressure regulator
> flow1-total fuel flow from pumps
> FPR-fuel pressure regulator, dumps excess back to sump
> flow2-fuel flow going to engine
> PS4-fuel pressure at engine injectors
>  
> So a delta pressure between PS1:PS3 and PS2:PS3 will indicate a 
> blocked fuel filter.
>
>     -----Original Message-----
>     From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
>     Behalf Of John Dibble
>     Sent: Tuesday, February 17, 2004 9:58 AM
>     To: reflector@tvbf.org
>     Subject: Re: REFLECTOR:Fuel filters
>
>     I have a cheap in-line filter and also worry about fuel
>     restriction.  I checked it after 10 hours and it seemed to flow as
>     well as a new filter.  So I feel comfortable it will last 100
>     hours anyway.  I guess the one good thing about fuel restriction
>     is that it should happen at the beginning of the takeoff roll
>     where there is room to abort.  Do they make filters that allow the
>     flow to bypass if the filter becomes plugged?  Or a separate
>     "pressure relief" valve that can be installed in parallel with the
>     filter?
>
>     John
>
>     Gilles Gratton wrote:
>
>>     Is anyone out there using the K & N Billet Aluminum Fuel filter?
>>     If so, do you recommend it?  I plan to use it on my Franklin
>>     engine to replace that small miniature glass filter which I have
>>     been using so far , successfully but with constant fear and
>>     apprehension that it will restrict fuel flow and starve my engine
>>     in a moment of high fuel demand.
>>     Gilles Gratton
>

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That's a nice setup.&nbsp; When I bought my Velocity it had 205 hours and no
filter, so I doubt that a little unfiltered fuel is going to be a big
problem.&nbsp; I did have an occasional slow fuel leak at the carbureator (I
could "fix" it by shutting off the fuel and running the engine until
the bowl was empty - on the ground of course.)&nbsp; My guess is that the
float valve was dirty and not sealing well.&nbsp; I just replaced the float
valve and seat so soon I will know it that was the problem.&nbsp; The bowl
and valve were very clean with no sediment.<br>
<br>
John<br>
<br>
Brian Michalk wrote:<br>
<blockquote type="cite"
 cite="midNGBBLKIBLMDNILPAICAJIEDJFIAA.michalk@awpi.com">
  <title></title>
  <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
  <meta content="MSHTML 5.00.2614.3500" name="GENERATOR">
  <div><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">I'm sure something like that exists, but
would you want unfiltered fuel plugging up your system?</span></font></div>
  <div><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">There are commercial filters that have a
sensor that tells you when the filter is plugged, but you could roll
one yourself by putting a pressure sensor on each side of the filter.&nbsp;
As the filter becomes clogged, the pressure across the filter
increases, showing up as a delta voltage on your sensors.</span></font></div>
  <div>&nbsp;</div>
  <div><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">I've gone perhaps a little overboard
instrumenting my airplane ... I do instrumentation for a living.&nbsp; I've
got sensors at each fuel pump output ... I'll draw a picture.&nbsp; It's
easier.</span></font></div>
  <div>&nbsp;</div>
  <div>&nbsp;</div>
  <div><strong><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">EFP--&gt;PS1--&gt;CV--&gt;FILT</span></font></strong></div>
  <div><strong><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \</span></font></strong></div>
  <div><strong><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
TEE--&gt;PS3--&gt;flow1--&gt;FPR--&gt;flow2--&gt;PS4--&gt;engine</span></font></strong></div>
  <div><strong><font color="#0000ff" face="Fixedsys" size="2"><span
 class="440115815-17022004">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; /</span></font></strong></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong>MFP--&gt;PS<span
 class="440115815-17022004">2</span>--&gt;CV<span
 class="440115815-17022004">--&gt;FILT</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong></strong></font></font></font>&nbsp;</div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">EFP-electric driven fuel pump</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">MFP-mechanical driven fuel pump</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">PS1-pressure from electric fuel pump</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">PS2-pressure from mechanical fuel pump</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">FILT-fuel filters</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">CV-check valve</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">PS3-pressure at input of fuel pressure
regulator</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">flow1-total fuel flow from pumps</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">FPR-fuel pressure regulator, dumps excess
back to sump</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">flow2-fuel flow going to engine</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">PS4-fuel pressure at engine injectors</span></strong></font></font></font></div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong></strong></font></font></font>&nbsp;</div>
  <div><font size="2"><font color="#0000ff"><font face="Fixedsys"><strong><span
 class="440115815-17022004">So a delta pressure between PS1:PS3 and
PS2:PS3 will indicate a blocked fuel filter.</span></strong></font></font></font></div>
  <blockquote
 style="border-left: 2px solid rgb(0, 0, 255); margin-left: 5px; margin-right: 0px; padding-left: 5px;">
    <div align="left" class="OutlookMessageHeader" dir="ltr"><font
 face="Tahoma" size="2">-----Original Message-----<br>
    <b>From:</b> <a class="moz-txt-link-abbreviated" href="mailto:reflector-admin@tvbf.org">reflector-admin@tvbf.org</a>
[<a class="moz-txt-link-freetext" href="mailto:reflector-admin@tvbf.org">mailto:reflector-admin@tvbf.org</a>]<b>On Behalf Of </b>John Dibble<br>
    <b>Sent:</b> Tuesday, February 17, 2004 9:58 AM<br>
    <b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:reflector@tvbf.org">reflector@tvbf.org</a><br>
    <b>Subject:</b> Re: REFLECTOR:Fuel filters<br>
    <br>
    </font></div>
I have a cheap in-line filter and also worry about fuel restriction.&nbsp; I
checked it after 10 hours and it seemed to flow as well as a new
filter.&nbsp; So I feel comfortable it will last 100 hours anyway.&nbsp; I guess
the one good thing about fuel restriction is that it should happen at
the beginning of the takeoff roll where there is room to abort.&nbsp; Do
they make filters that allow the flow to bypass if the filter becomes
plugged?&nbsp; Or a separate "pressure relief" valve that can be installed
in parallel with the filter?<br>
    <br>
John<br>
    <br>
Gilles Gratton wrote:<br>
    <blockquote cite="midDAEDKOMCBHINGJEIJCOJIEHGCJAA.gratton@magma.ca"
 type="cite">
      <meta content="MSHTML 6.00.2800.1400" name="GENERATOR">
      <div><font face="Arial" size="2"><span class="810285815-15022004">Is
anyone out there using the K &amp; N Billet Aluminum Fuel filter? If
so, do you recommend it?&nbsp; I plan to use it on my Franklin engine to
replace that small miniature glass filter which I have been using so
far , successfully but with constant fear and apprehension that it will
restrict fuel flow and starve my engine in a moment of high fuel
demand. </span></font></div>
      <div><font face="Arial" size="2"><span class="810285815-15022004">Gilles
Gratton</span></font></div>
    </blockquote>
  </blockquote>
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