On 2010-09-05 9:31 PM, Glen Davis wrote:
Can you help me diagnose why the engine keeps quitting after 30
seconds or so?
Glen,
Here's one possibility:
That sounds typical for a */_partial_/* blockage of a fuel line. There
is fuel flow, but it's insufficient. Therefore, when you start the
engine, it flows until the fuel supply in the area between the blockage
and the engine is used up, then the engine dies. The line slowly
refills and the process can repeat.
When this happened to me in the air, the engine stopped, then restarted
then stopped then restarted - the restarts were automatic as the engine
was windmilling. The running times got shorter and the stops longer (as
the metal fitting through the firewall froze up more and more) until
there were no more starts.
I'd urge you to look for a partial blockage somewhere between the nose
tank's fuel and the engine. Possible thoughts include sloshing compound
coming loose - perhaps even floating around in the nose tank. Or,
sloshing compound or something else in a fuel line. How about a
partially blocked fuel strainer?
I'm sure there are other possibilities. This matches my one similar
experience.
Suggested test that may, possibly, give useful information: I'd expect
the run times to be much longer at idle than at high power if this is
the cause.
As an aside to others: My throttle on that flight was set for high
speed cruise at perhaps 75% power. Perhaps if I'd reduced power to
minimum stay-level power it would have kept running continuously. Even
better, if I'd known to use the primer to provide fuel to the engine, I
could probably have flown the final 7 miles to my home airport and made
an on-airport landing instead of a farm field (with, luckily, no damage
or injury).
Other ideas for which my knowledge level is near zero and they may not
apply: wrong type of carb valve needle, bad float ? ? ? ? ?
Ed
