Ask The Editors: 400EX Turns Over But Won’t Start
Refusing to fire up.
It sounds like you satisfied one of the three conditions needed for ignition in an internal combustion engine, but what about the remaining two? Every engine needs the right mixture of fuel, air and spark to light up. You have fuel so now it’s time to make sure you’re getting the other two ingredients.
Check your machine’s air intake – is the air box clean inside? No obstructions? Air filter element present, oiled and in place? If all of that checks out, follow the intake toward where it meets with the combustion chamber – no visible cracks in the rubber boot? Not disconnected or loose at the clamp?
If your air intake system all checks out, time to investigate spark. Is the plug old? Sometimes it’s as simple as replacing a fouled out plug with a new one.
To check your 400 for spark, remove the spark plug from the engine then reinsert the plug back into the coil wire as if it were installed in place. Now position the plug’s electrodes close to the engine to ground it but without actually touching. Now try turning over the engine. (With an electric start model like the 400EX, it’ll take someone pushing the starter button while you hold the plug). If you see spark flickering from the end of the spark plug, your engine is getting spark.
Begin your investigation here and report back with your findings and we’ll help you go from there.
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