There is another possible cause - as those who have had BMW bikes with Bing
carbs - they sometimes dump excess fuel if the float sticks. I have just
been looking at a friends 914 which has a sort of aluminium fuel catcher
arrangement underneath the carbs which is attached between the manifold and
the carb. This fuel catcher has a drain to the bottom of the cowling. I
assume that this was to drain fuel if the carbs should dump fuel - in other
words the same thing as the Beemers.
There was I seem to recall some corres about this earlier on in the year.
Will
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of John & Paddy
Wigney
Subject: Europa-List: Re: Fuel smell 912S XS front fire wall
<johnwigney@worldnet.att.net>
<<<<<<<
From: "ctsmallwood"
Subject: Europa-List: Fuel smell 912S XS front fire wall
Hi All Occasional slight SMELL of fuel. ALL connections fully checked. On
both sides of fire wall(with developer).Fire Wall sealed prior to engine
fit, and again after engine/ flights.All Ally fittings aft. firewall Only
place I believe it may be originating from is the Air Box. 2 small holes
under each connection to the Carbs(in Airbox). and entering cockpit thro
throttle and brake slots via tunnel Any help greatly appreciated Regards
Colin Smallwood
>>>>>>>>>
Hi Colin,
These comments are really directed at others who may have this problem since
I believe that you may have already used a leak detector (developer?). I
installed the factory supplied fuel hose as per the standard kit
instructions. After the first 100 hours I had an annoying intermittent fuel
smell. I carefully inspected and checked all connections without finding
anything. The problem seemed to get worse and I was still unable to find
anything. I then procured some fluorescent leak detector additive. (Mine was
Dye-Lite, see http://www.tracerline.com/ )
Anyway, before I had chance to try the detector, the leak developed into a
drip. At the main tank outlet, the hose had a crack under the hose clamp. I
replaced the length of hose.
My conclusions were :-
If I had to do it again, I would use aluminium tubing with AN flare fittings
for all fuselage fuel lines as I believe you have done. Ahead of the
firewall, I would probably use braided hose with swaged-on threaded hose
fittings.
The factory supplied fuel hose with my kit has fabric braid on the outside
only. If there is a small leak, the fuel slowly wicks into the braid,
evaporates and is invisible. I believe that braid reinforcement in the wall
of the hose is much more preferable and will minimise hose cracking. If you
choose to use a fluorescent leak detector dye, it is important to get a good
quality UV lamp or you will have inadequate illumination.
Finally regarding the airbox, I notice that there is quite heavy staining
inside my airbox stub tubes from 100LL fuel dye. I usually fill with 100LL
so I assume there is quite a lot of neat fuel in there at some time. Am not
sure how that happens. An option for you might be to put small drain tubes
onto these drain holes and lead them to behind the wheel well.
Cheers, John
N262WF, mono XS, 912S, 430 hrs
Mooresville, North Carolina
704-664-4167
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