Hi Frans
Have exactly the same problem with my 914 - ok straight away but short
break very difficult to start - but have found if I do 2 things
I can get it to start agin with little extra effort.
1. Open both inspection hatches once you have landed - allows some of
the under cowl heat to escape.
2. To start - switch on a fuel pump till you have good fuel pressure ( i
have a fuel pressure warning light - wait till it goes out) then switch
OFF the fuel pumps - open throttle to about a 1/4 +/- and crank till it
fires - once engine is running - switch on fuel pump but be prepared to
switch off again if engine starts to die - soon running smooth and fuel
pump can be left on as normal
Regards
Mike
Dr Mike Toft BVSc
083 654 6655
P O Box 602
Linkhills 3652
watervet@mweb.co.za
On 13 Mar 2012, at 11:22 PM, Tim Ward wrote:
>
> Frans,
>
> Don't have a 914 but I know others who have suffered the same problem
with the 912S and , for what it is worth, they always
> open their oil and coolant doors on top of the top cowling to allow
faster cooling of the engine compartment during stopovers.
>
> Otherwise don't mention starting problems to me! I have now got to
replace my Sprag Clutch due to cold starting problems with my 912S
> at 300 hours!! Always had it and got worse with time. So watch out
when trying to persist in trying to start the motor as it quickly
destroys your Sprag Clutch. I have also the
> old mono "classic" engine frame which doesn't allow enough room for
the new Heavy Duty Starter which Rotax suddenly decided was
> necessary for the 100 HP 912S. So, after replacing the Sprag Clutch,
the Rotax man is going to look at how to fix the starting problem
> in cold weather. Maybe a case of redesigning the engine frame to allow
for the HD Starter?
> Once it is going there is no problems with starting, so I haven't got
the vapour lock problem.
> All a bit frustrating as you have found out and expensive. Might as
well throw in the 912iS, but that may unleash a different set of
problems.
>
> Anyone have some input to my problem? Tried new battery, preheating
the engine which has helped, haven't tried the soft start module,
> and kicking the tyre!!
>
> Cheers,
>
> Tim
>
>
>
> Tim Ward,
> 12 Waiwetu Street,
> Fendalton,
> Christchurch 8052
> New Zealand
>
> Ph; 03 3515166
> Mob; 0210640221
>
> email; ward.t@xtra.co.nz
> -----Original Message----- From: Frans Veldman
> Sent: Wednesday, March 14, 2012 9:01 AM
> To: europa-list@matronics.com
> Subject: Europa-List: Rotax 914 starting problems when hot
>
<frans@privatepilots.nl>
>
> Hi everyone,
>
> I guess I'm not the only one having this problem. The main problem
here
> is that I don't understand why it is happening.
>
> If I arrive at an airfield in hot weather, I can restart either right
> away, or after a considerable time. If I just refuel without having a
> meal, I get into a time window where the engine has difficulties
starting.
>
> It is a vapour lock problem of some sort, but I don't know how this
can
> happen. Sure, the inside of the cowling is hot and residual heat from
> the turbo is, without the large fan upfront turning, cooking the fuel.
> But I thought that the 914 is supposed to be immune from the problem.
>
> Up to the pressure regulator the fuel is recycling when I switch on
the
> electric fuel pump. Any vapour up to the pressure regulator is
directed
> back into the tank and being replaced by fresh and cold fuel.
>
> The carb bowls might have been cooked empty, but then the floats will
> have dropped and fresh fuel will pour in as soon as I switch on the
> pumps. The fuel line between the pressur regulator is not recycled but
> if it contains vapour then it will escape via the opened carb needle
and
> not raise the floats, so it will gently escape until being replaced by
> liquid fuel, being driven there by the electric pumps.
>
> So... why won't then darn thing just start?
>
> Yesterday I was exactly experiencing this problem. After arriving at
an
> airport to go to the service center for the bi-annual pitot and static
> systems test, and with the engine switched off for about ten minutes I
> couldn't restart it. No matter how long I kept the fuel pumps running,
> applied choke, (just in case the mixture was too lean) or was just
> cranking with the throtthle wide open to vent the cylinders (in case
it
> was too rich), the engine would just crank without even a faint single
hit.
> So I abandoned the plan to taxi to the refueling station, and had a
> lunch instead. Of course after that the engine started up right after
> just a half turn of the prop...
>
> So... why is this happening? I'm interested in solving this problem,
but
> primarily I want to know why this is happening because according to my
> reasoning it shouldn't be happening in the first place. What am I
> missing here?
>
> Oh BTW, on the return home I got caught by non predicted early set in
of
> night fog, with a very rapidly dropping cloud base (never seen it
> falling that fast). With my home base being the closest and most
> promising airfield once I got forced down to 500 feet I advanced the
> throttle to 100% (not 115%) and got over 155 knots IAS worth out of it
> on my freshly calibrated ASI, which was quite an experience so low
over
> the ground. At my homefield I arrived less than 15 minutes later with
> the local cloud base still at 1000 feet (as announced/predicted by ATC
> half an hour earlier), but I was thankful nevertheless to have been
able
> to speed out of that threathening situation that fast. If it weren't
for
> the obligatory static/pitot test to renew my airworthiness review
> certificate I wouldn't have been flying at all that day, so much for
the
> bureaucrats that want to enforce my safety this way. Anyway, the
> pitot/static systems worked flawless (I would have had noticed it
myself
> it if they weren't) and I'm good to apply for renewal of the desired
> certificate.
> All this while I had unwittingly broke my smallest toe by bumping into
> my wife unintentionally (honestly!) and was undergoing this flying
> experience with some discomfort to enhance the flying experience even
> further. At least the latter problem has been diagnosed correctly
today,
> so now I just want to get diagnosed the vapour lock problem as well.
Who
> can shine some light on this mystery?
>
> Frans
>
>
>
>
>
>
>
>
>
>
>
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