Hi Frans
I have had exactly the same problem as you but found a easy way to start
hot,
I turn off both pumps with about a 1/4 throttle it will fire up and run but
you must
leave the pumps off until she starts to falter, I then use the main fuel
pump because
its using the coolest fuel and she will continue to run, it has worked for
me with
temps up to 38C,
best wishes
Ivor
On 13 March 2012 20:01, 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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