How do I prevent my car from flooding?
The RX-8 has proven to be a lot more susceptible to flooding than what most consumers are used to.
Flooding occurs when the car is started (cold) then shut down before the engine is warmed up. The reason for this is that the car injects more fuel into the engine when it's cold. When you shut the car down, excess fuel can remain in the engine. The next time you start it up, you'll find the engine turns over, but it can't spark. This can also lead to your spark plugs fouling.
Mazda has put out a TSB to help lower the chances of this issue taking place:
APPLICABLE MODEL(S) / VINS 2004-2005 RX-8
Some vehicles may experience difficulty starting (cranks no start). This may occur after driving the vehicle a short distance without engine reaching normal operating temperature. Examples: starting a vehicle and moving it to wash it, engine stall due to mis-application of clutch then restart. This commonly occurs at port facilities or dealer lots where vehicles are frequently started cold, moved for short distances and then turned off. This concern may also occur due to low cranking RPM during engine starting.
A cranks, no start condition may be caused by fuel flooding resulting in either fouled spark plugs or lower than normal compression.
What Mazda did was to recalibrate the PCM so that it injects less fuel than it did previously.
They also issued upgraded batteries (more juice) and a more powerful starter. The battery that shipped with the original RX-8's was quite weak, and the combination of excess fuel, weak battery, and weak starter meant the car would see the flooding issue far more than it otherwise might.
Even with the upgraded hardware, the RX-8 can still flood.
The BEST way to prevent your car from flooding is to drive it around till it's warmed up. This means a ~5 minute trip. If you're unable to drive for 5 minutes, Mazda recommends you rev the engine to 3,000 rpm for 10 seconds, then switch the car off. As you turn the ignition key, depress the throttle so that the excess fuel is spun out of the engine. I do not have much faith in this process however, as I have flooded after following the procedure precisely.
Here's my car being towed to the dealer: