Hot start on my 914 is no choke, closed throttle, start cranking and slowly
advancing
the throttle untill it fires up.
Kevin
914 mono 400hrs.
On Mar 13, 2012, at 1:01 PM, Frans Veldman <frans@privatepilots.nl> wrote:
>
> 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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