Evolution Engines 91NX - Manual (Page 10)

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fuel to the field on any given day. This allows
their main supply of fuel to stay at home in
a controlled storage environment, virtually
ensuring problem-free fuel.
Tip: Do not store plastic fuel jugs on metal or
concrete surfaces, this can also cause
moisture contamination.
How to Tell If Your Glow plug Is Bad
The glow plugs on the market today are
designed to provide good service to the user
and may last a long time or a short time, all
dependent upon the way you choose to
operate your engine.
Physical indications that you might need to
change the glow plug are:
1. Twisted or mangled glow plug elements
(usually caused by too high a compression
ratio).
2. Small “bumps” are attached to the glow
plug element. This will generally be most
noticeable during the break-in process.
These are actually tiny pieces of aluminum
that have attached to the element and will
severely hinder the operation of the glow
plug.
3. The glow plug element is no longer shiny
but is a dull, almost a white powder color
(this just comes with age and is a
by-product of the catalytic reaction). The
shinier the wire, the better the catalytic
reaction can be.
Operating indications that you need to change
your glow plug are:
1. The glow element will not light with a
charged glow igniter. This indicates that
there is a physical short or breakage in the
element wire itself.
2. The glow plug lights but the engine will
not continue running once the battery is
disconnected (this is usually an indication
of the microscopic particles discussed
earlier).
3. Glow plug lights, the engine runs, but there
is a perceptible loss of rpm at full throttle
when the battery is disconnected. This is
a typical indication that the white powder
residue is building to the point that the
catalytic reaction of the glow plug is no
longer anywhere close to being optimum.
Troubleshooting Guide
Issue Possible Cause Possible Solution
Engine Won’t Fire Glow starter not charged Charge glow starter
Glow plug burnt out Replace glow plug
No fuel is getting to the
carburetor Check tank, fuel lines reversed
Clogged fuel filter, clean or
replace
Clunk wedged at front of fuel
tank, clunk line kinked Hold airplane nose up and give
a quick downward jolt to
dislodge clunk
The starter is reversed Reverse the polarity on the
starter cables
Engine Quits Repeatedly Needles need adjusting See adjustment procedure
Bad or old fuel Replace with fresh fuel
Worn out glow plug Replace with new EVOGP1 glow
plug
Engine Runs Inconsistently Hole in fuel line Replace fuel line
Bad or old fuel Replace with fresh fuel