Hi Frans
Just a few ideas:
Differential pressure gauge may
not be speaking absolute truth
The fuel pressure regulator is
adjustable, you could lower a pound
You may have more of a
restriction on the return line than is desirable, make sure fittings you
are using are oflarge bore varient. supplied with my kit were both
large and smaller bore (more restricting). also look for kinks or pinches.
Rotax tells you max. restriction they want, worth measuring. Measure and
or fix restriction before you adjust regulator.
Fuel pressure
needs to be higher than airbox pressure or it won't flow into carb bowl.
Too high and it could overcome needle valve and leak. That said there are
plenty of 914s flying with parallel fuel systems that blow way higher than
5 PSI and pilots sday seems fine. 6 PSI is not very high, but if it were i
I would get it down a little if i could. Perhaps you can check
gauge/sender calibration?
Ron P.
> -->
Europa-List message posted by: Frans Veldman
<frans@privatepilots.nl>
>
> On 07/02/2010 03:57
PM, rparigoris wrote:
>
>> If you were to have such a
circuit, you would want to have it turn on
>> second pump when
it falls below ~ 2 PSI differential pressure (fuel
>> pressure
going to carb less the airbox pressure).
>
> I agree you
should have a differential fuel pressure switch. The Rotax
>
maintains a specific fuel pressure OVER the airbox pressure (which
> varies with power setting and altitude).
>
>>
not be the thing to do if you have parallel pumps because you can
>> blow over the ~ 5 PSI differential.
>
> I
have the serial pump layout, but with a full tank and both fuel pumps
> on, the differential pressure raises to 6 psi while the engine is
> running on low power. I was concerned that this higher fuel
pressure
> would choke the engine during the approach, when both
fuel pumps are on
> and the power setting is low, but I have not
experienced any problems
> with it.
> Yet I would like
to know whether this is normal. During flight, with one
> pump
on, the differential pressure is always around 4.5, regardless of
> power setting. Interestingly, the fuel pump connected to the Andair
> gascolator provides a lower pressure than the fuel pump
connected to the
> disposable fuel filter.
>
>
Frans
>
>
>
>
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