Today's Message Index:
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1. 11:37 AM - Re: Re: Fuel return line (Sacha)
2. 03:19 PM - Re: Fuel return line (Roger Lee)
3. 04:29 PM - Rotax Fly Dat (Alan Carter)
Message 1
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| Subject: | Re: Fuel return line |
Hi Roger
I can see why hot fuel would exacerbate vapor lock problems and this
conversation has convinced me to firesleeve my fuel lines. But why does a
return line improve the situation. And I would have thought higher fuel
pressure would lower the incidence of vapor lock (as it increases the temp
at which fuel vaporizes). Can you shed more light on why higher fuel
pressure is bad?
Regards,
Sacha
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Roger Lee
Sent: Thursday, 04 April, 2013 19:43
Subject: RotaxEngines-List: Re: Fuel return line
--> <ssadiver1@yahoo.com>
Hi John,
Here's the issues.
Many of the planes from yesteryear wasn't a problem. They were open air
engines so hot fuel lines weren't an issue and the old style fuel pump
didn't have enough excess pressure to be an issue. Come up to date with many
of the newer LSA and Experimental aircraft with nice tight cowls and then
throw in on top of that too many owners fail to install the fuel and oil
lines in fire sleeve then heat inside the cowl makes a night a day
difference. Vapor lock. I see it alot now days with tight cowls. Fire sleeve
not only protects from fire, but helps with excessive heat too. Now comes
along the new Rotax fuel pump that puts out more pressure and then add on
top of that someone who likes to run an electric pump all the time which
adds
.5 -1.0 psi more and the fuel then can't be controlled by the float needle
valve and it pukes out the vents all over a hot engine, on hot exhaust
manifolds because some didn't bother to install carb drip trays and now we
have an issue. Now add that owners haven't rebuilt or replaced an older
float needle valve and now we definitely puke fuel and the engine runs
rough.
Just a side note* Exposed fuel lines outside of fire sleeve tend to
deteriorate faster than fire sleeved fuel lines.
So the bottom line is application is everything and sooner or later your old
pump will die and the new pump is all that is available. It's so easy to add
the re-circulation line and never have to look back. On any flight the float
needle valve can start leaking then you have the issue too.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated Rotax Repair Center - Heavy Maint.
Rated Home 520-574-1080 TRY HOME FIRST Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=397863#397863
Message 2
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| Subject: | Re: Fuel return line |
Hi Sacha,
Higher fuel pressure may lead to flooding of the carbs because we tend to use low
pressure to start with. Using a recirculation line keeps cooler fuel moving
through the system to help prevent the vapor lock. It keeps cooler fuel within
the lines while flying. If your sitting still on the ground with the engine
off and it was just shut down then the fuel just sits there and cooks. A re-circulation
line moves cooler fuel back up to the carbs much faster after a restart.
The re-circulation line also helps keep vapors out of the fuel pump just
because the system moves more fuel and it is coming from a cooler point within
the system.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=397980#397980
Message 3
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Hello All
I have a Rotax FlyDat on my 914,
I notice it has a small battery located on the back side.
Master switch on, Flydat cycles, shows temp,and hours,
turn the key ,Starting the engine and display recycles nothing showing till after
its completed its cycle, then come in with all the temps and pressures.
But during the vital starting stage I have nothing showing.????
Alan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=397987#397987
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