Bill, I had a complete fuel pump failure but did not experience an intermittent in between, possibly because the pump failure was not noticed until the other was shut off.
I believe my pump failure was due to insufficient fuel to 1 pump caused by a fuel routing change made prior to flight which revealed failed pump.
If the pumps are operating with low fuel flow (unported) they may be damaged – but I don’t know how long this takes – my flight was about 15 minutes.
If nothing else has changed in your system, then your plan of action to clean the gascolator, replacing fuel filter and pump should clear things up.
I would also recommend a thorough ground run of each pump with high rpm and low rpm in the pre-flight checklist.
Do you have aluminum or fiberglass tanks?
Check the venting of your fuel return lines.
Jeff
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From:
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"Bill Bradburry" <bbradburry@bellsouth.net>
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Subject:
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Intermittent fuel pressure loss
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Date:
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Mon, 27 May 2013 10:09:06 -0400
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To:
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"'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
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Has anyone had an instance of intermittent failure of the fuel pumps? A
couple of days ago the engine started to intermittently lose power and
changed tanks. (both tanks were low, about 5 gal in right and 10 or so in
left) The problem stopped so I thought I had unported the right tank.
Several minutes later it started again on the left tank and I turned on the
other fuel pump. That seemed to stop it again. I still suspected that I
had unported the tanks.
A couple of days later, I took off with about 45 gal and after about a 30
min flight, the engine lost power again twice. I turned the other fuel pump
on and the problem stopped.
My fuel system goes thru a Gascolator then to the two pumps, then to a fuel
filter. I assume that the Gascolator or the fuel filter could be getting
clogged, but I don't think that the other pump would bring the pressure back
if that were the case. I only have about 70 flight hours on the pump and
maybe about 100 hours total including ground runs.
Also on the flight back, I had both pumps on and showing 40 lbs of pressure.
I then turned the secondary pump off and the pressure held at 40 lbs. This
strikes me that it is an intermittent pump failure. I plan to clean the
Gascolator, replace the fuel filter, and replace the pump.
Any thoughts, suggestions, experiences?
My wife was with me on the last incident and I don't think she is interested
in trying to join Ed's glider club!
Bill B
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