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Starting a flooded engine (Carburetor engine)

You came back to your plane after having a $100 burger, two hours away from your home airport. Methodically, you run through the entire checklist, and followed the priming procedures as described for a cold start. You’ve left the aircraft parked on the apron for about half an hour. By now the engine should have cooled down enough to warrant a cold start prime, right? Ten seconds after priming, you realised that the engine still would not turn over, even though you have cranked for more than five seconds. “Possibly more priming is required,” you thought, and you did it again.

By now, the engine has already been flooded with too much fuel, and no matter how you crank, it just would not start. “Something’s wrong with the engine,” you muttered, thinking about the eight hour car ride home from this remote place.

In fact, nothing is wrong with the engine. The excessive fuel in the engine cylinders is just not igniting because the air/fuel ratio is so out of balance due to your repeated squirting of fuel into the cylinders. There’s just too much fuel caused by your over priming, and it is very important that you recognise this is a symptom of a flooded engine before you burn out the starter motor, or worse still, calling your wife to drive 8 hours here to pick you up.

To recover from a flooded engine, the aim is to correct the fuel/air ratio, and you may achieve that by doing the following:-

Mixture Lean
Throttle Full
Start cranking the engine. When the air/fuel ratio is right, the engine will start.
When the engine turns over, bring the throttle down and mixture to rich

Just remember, do not crank for more than 10 seconds at a time, and let the starter motor rest for 10 minutes after cranking 3 times. Refer to the POH for more information.

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