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I ran my engine today with all the firesleeve installed and the new sump tank vent. After 3 engine runs at WOT, the water temp hit 230 (and climbing), and the engine started acting just like it did the day of my forced landing. Sputtering, erratic and finally just it quit, and would not restart. I turned on my inline Facet fuel pump. It took 3 or 4 seconds, then the engine came back to life. I was able to taxi back to the hangar (I used about 1/2 throttle to get the aircraft rolling, then throttled back a bit to taxi). My Facet pump is between the main tanks and the sump tank.(after the fuel selector valve). The EFI pumps are after the sump tank and before the fuel rail/regulator. The unused fuel from the regulator returns to the sump tank. There is no way the engine would run without the Facet pump to push fresh gasoline into the sump tank, which was obviously filled with gas and bubbles after the thorough heat soaking it received. With the Facet pump still on, and taxiing under reduced power, the temps came down from 240 to 210 by the time I reached the hangar, and shut it down. My sump tank is vented with a 3/16" OD line on the top, which goes into the top of my left fuel tank. The line is opaque, and I can see fuel movement going through the new vent line when the Facet pump is turned on. Unfortunately, I can't tell if it is clear fuel or bubbles, or a mixture, as the line is opaque rather than clear, but I can definately see motion and tell it's direction of flow. Hope this more helpful than confusing. Paul Conner
----- Original Message ----- From: "Jim Sower" <canarder@frontiernet.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, February 16, 2005 10:41 AM
Subject: [FlyRotary] Re: Vapor Lock
<... HP pumps are capable of moving LOTS more fuel than a Facet pump ... HP pumps would be drawing fuel through the Facet pump ... because the Facet can't keep up ...>
You're right. I hadn't thought of that. Facet pumps deliver 30 gph. I'll check how much my HP pumps are putting out. Wonder if Facet delivers more at lower head pressure, objective being to push fuel through filter and plumbing so there's less chance of pressure drop that could cause the fuel to vaporize.
Back to the drawing board ... maybe ... Jim S.
Marvin Kaye wrote:
Jim Sower <canarder@frontiernet.net> wrote:
"""
I have a canard, but I will have a Facet pump near (and below) the wing tanks
to PUSH the fuel through the filter and fuel flow transducer. I don't want
the HP pumps to SUCK through the filters and etc. for fear of vaporizing the
fuel.
"""
This doesn't make any sense to me, but perhaps I'm missing something. The HP pumps are capable of moving LOTS more fuel than a Facet pump. Consequently, it seems to me that the HP pumps would actually be drawing fuel through the Facet pump when they're switched on, simply because the Facet can't keep up with what's being drawn out of the sump tank by them. Additionally, a return system needs 2 flow transducers, one for the feed line and one for the return... then the display instrument's electronics deduct the return flow from the feed flow to properly calculate actual through-the-injectors instantaneous flow data. (The EI fuel flow instrument uses an FFDM-1 (fuel flow differential module) to do the job, GRT EIS does it itself, as do other flow instruments with both feed and return inputs.)
As long as the filters are rated to flow as much fuel as the HP pumps are capable of pushing I don't see that (vapoization) as an issue. The filter elements do need to be kept clean, and are a replace-at-annual item.
<Marv>
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