Fuel problems
After having a carb. related problem recently, I would like to give possible
advice as to what I was told is the correct way
to filter the fuel. I had an in-flight problem which caused the engine to
suddenly cut back power, but not die. It would run
at medium RPM's, but not high. I had a small, perfectly formed, mostly clear,
'ball' of something form in the base of one
carb. It was mostly clear, but slightly red/orange in color. It caused the one
carb to starve for
fuel. (yes, I did take a good digital picture of it)
Dean at Lockwood, gave me what I feel is great information. Ethanol fuel can
cause many different problems. I have not been
using ethanol intentionally, but in Iowa, USA, it is very common, and can PAPER
FILTER(S). Ethanol degrades them. I have
been. He said to also use a gascolator. I now have one, but did not before. He
said to go from the tank to the gascolator
first, then thru fine screen filter(s), then to the carbs. Also, advised to put
heat insulation material on the two exhaust
pipes that are under the carbs. Together we therorize that heat on the base of
the carbs. caused whatever varnish or whatever
to help form the mostly clear ball at the very center bottom of the bowl that
starved my one carb.
After installing the gascolator, I now am seeing very fine 'strands' of what
must be off the filters, floating in the base of
the fuel sampler. I was going thru 3 of the paper filters, which I felt was
extra safety, but may actually have been part of
my problem. I was never told NOT to use paper filters. I do believe they were
furnished with my kit. That is not being
critical, I just was not told differently.
I hope this may help any others from having a very scary situation happen to
you.
Thanks,
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I think that if you check the Rotax manuals that you will find that they all
state that paper filters should not be used on
either 2 or 4 stroke Rotax engines! The reason for this is that water can clog
the paper filters. I also know that Rotax
makes paper filters and many folks use the things. I have stopped using the
paper filters and switched to the metal mesh sold
by Lockwood because I believe that the E-10 ethanol fuel now being used in our
area (Maryland) will cause more of these
problems.
I want to mention here that additional similar problems are developing with the
ethanol in our fuel. The ethanol is causing
problems with older fiberglass fuel tanks in both aircraft and boats since many
types of epoxy used in fiberglass fuel tanks
are attacked by the ethanol. What happens is that the glass fibers in the wall
of the tank are released into the fluid and
these clog the filters or passage in the carb. Fiberglass tanks are now normally
made with vinyl-ester resin and these are
not attacked by the ethanol. If your region is switching from MTBE to ethanol
you must also be aware that "stuff" that might
have built up in your fuel tanks, lines, and carb over time while using MTBE
might be dissolved by the ethanol.
A "Jello" type substance that will also clog paper filters results and, in fact,
a guy in our USUA club recently had an
engine failure in A Rotax 447 engine where this is suspected to have been the
cause.
John Bender
=================================================================
Thank you ! More good information. I have used ethanol in my cars for years, and
have had no problem. I would guess that some
got into my system over the last 3 years, and that may well be what happened. I
had not remembered seeing any information
from Rotax, but I was building from the pieces supplied in my kit, and just
never questioned it I'd guess. Hope this
information helps others anyway. I also was one that did not think a gascolator
was needed, but I can see it lets you know
more about what has settled in the bottom of it before going on to create
further problems.
Thanks again.
================================================================
John,
The Rotax 912 installation manual, chapter 14 Fuel System page 38 says not to
use paper elements in fuel filters. This
subject came up a long time ago on this list and there was widespread and
general disagreement, as I recall! I use the little
K&N plastic filter with the brass sintered element. A gas collator is better,
but where and how did you mount it? The lowest
point in the fuel system would put it under the belly of the airplane!!
Otherwise I would have installed one.
John & Jack,
===============================================================
John raises a good question; where did you mount the gascolator, and the non
paper filter John? Any pictures? I've never
used gas with ethanol in it, and can still find gas free of ethanol at our local
BP station. I'm not sure how long that will
continue, so am interested in installing a gascolator, and the fuel filters like
John described.
Chuck
==============================================================
Jack
I took the Rotax repair training from Eric Tucker. Regarding ethanol fuel used
in Rotax engines, he is consistent with a
seminar with Phil Lockwood at Oshkosh. The Rotax books say up to 5% ethanol in
the correct octane of fuel is acceptable. They
both went on to say they have seen no engine problems specifically with 10%
enthanol. They went on to say all the components
in the fuel pump and carbs are not affected by ethanol. The problem is with
other parts of the fuel system. I have used 5-10%
ethanol premium fuel in my plane since the beginning and there have been no
problems at all. I use a brass screened filter
(but admit a gascolator would be best). The idea is that small pieces should be
allowed through the system and larger items,
that could block a jet, should be prevented from getting to the carb.
Dale
==========================================================
Chuck,
Sorry, I answered Jack before I read your message. Per Dean at Lockwood, and now
I agree, go straight from the tank to the
gascolator which I described to Jack. From there, you can add the fine mesh wire
screen filter(s) between the gascolator, or
after the fuel pump going to the 'T' the goes to each carb. I tried to stay away
from the exhaust pipes and direct heat as
much as possible. I felt it was best after the fuel pump, but I know some may
say otherwise to that also. The gascolator
should take any serious items out of the fuel before it gets to the pump, (it
has a fine screen in it also), so a filter
after the pump, (easy to see), I felt was best. If others think differently, I
'd like to hear why. Hope this helps. Pictures
- I have not taken one of my gascolator mounting yet, but will try to remember
to. Supposed to rain this weekend, so I may be
able to do it then.
Thanks,
John Bender