How to Troubleshoot your model airplane engine

Symptom

Diagnosis

Fix

Engine Does not Fire

Prop flipped too weakly

Flip prop vigorously

Battery low

Charge battery

Glowplug burned out

Replace plug

Battery wires faulty

Replace wires

Engine flooded

Remove plug, rotate prop to remove fuel

Engine not primed

See how to start.

Engine fires intermittently

Battery voltage problem

Check recommended voltage

Too much priming

Disconnect battery and wait a few minutes.  If still unsuccessful, Remove plug, rotate prop to remove fuel

Prop flipped too weakly

Flip prop vigorously

Engine starts, then rpm decreases till engine cuts out

Fuel mixture too rich (too much fuel)

Close needle valve half a turn, then restart.

Engine starts, then rpm increases till engine cuts out

Fuel not reaching engine

Check for:

a)    fuel in tank

b)    fuel tubing not cut or kinked

c)     carburetor not clogged with dirt

Engine starts, then stops as soon as battery wires are disconnected

Fuel mixture too rich (too much fuel)

Close the needle valve a small amount

Glowplug incompatible with fuel used

Change plug type or fuel type