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2) Connect the fuel tubing from your fuel pump to the
fuel inlet nipple. Pump fuel. It’s a bit messy but only
takes a second or so. Almost invariably, the culprit is a
particle of dirt lodged at the point where the tip of the
needle valve throttles engine fuel. The back flush blows
that particle out.
3) You’ve probably got excess fuel in the engine. To
avoid hydraulic lock damage to your engine, remove
the glow plug and washer and blow the excess fuel out
of the engine with your electric starter.
4) Replace the glow plug, washer, needle valve, and
reconnect the fuel tank line. Adjust the needle valve to
its previous setting.
5) Check your engine and fly.
Avoid getting dirt in the carburetor
In three words—use fuel filters! Somehow, dirt, or
minute solid particles get into our fuel. In order to keep
these particles out of my engines, I started using
multiple fuel filters. Use one at the bottom of the fuel
bottle or can. You’ll soon find that once in a while, this
first filter gets a bit clogged. Back flush it, and you start
drawing fuel again. Use another fuel filter between the
fuel pump and the aircraft fuel tank. Finally, always use
a fuel filter between the aircraft fuel tank and the
engine. When fueling the aircraft, disconnect the fuel
line at the tank side of the engine fuel filter. This system
works and eliminates the old problem of having to
periodically back flush the engine to get rid of dirt.
When flushing fuel filters, make sure you flush them
both ways before inserting them back into the fuel lines.
from The Beacon
Miramar Radio Control Flyers
Dirt in the Carburetor
Every now and then, when you can’t get an engine to
run right, the culprit is dirt in the carburetor. The engine
was running fine last time out, and you haven’t
changed the engine settings. Now it quits at full power
and won’t idle. What’s wrong?
If you haven’t been to the field in six months, make
sure you’re using fresh fuel! Fuel that’s been sitting
around for months, especially if it’s left in the fuel tank,
could be your problem. If it’s not the fuel, put in a new
glow plug. Check the clunk hung up in the fuel tank for
clogged fuel lines. If your aircraft comes to a sudden
stop, the fuel tank clunk can slide forward, getting stuck
in that position.
Having eliminated these possibilities, you may have a
fuel draw problem caused by dirt in the carburetor,
most likely at the narrowest part where fuel is drawn
through the needle valve. If backing out the needle
valve doesn’t allow the engine to run rich like it should,
it’s time to flush the carburetor.
At home, you can disassemble the carburetor for
complete cleaning. At the field, a quick fix is to back
flush the carburetor with fuel. This doesn’t require
carburetor removal and can be done in just a few
minutes.
Cleaning the carburetor
1) Check to see where the main needle valve is set.
Then remove it and set it aside. Remove the fuel inlet
tubing. Adapt these procedures to engines with remote
needle valves.