Car not starting after very short run earlier

The engine is flooded. Remove the fuse for the fuel pump, then crank for 10 seconds. This will clear out fuel from the cylinders. Only solution is to allow the engine to heat up properly before shutting off.

How come this doesn't happen to all cars? What's the factor that makes some flood and others not? I have heard of it happening before, but never experienced it myself is all, so was just wondering heh.

I think it's down to the ECU. Some engines will ingest latent fuel that's been injected in the milliseconds prior to the engine shutting down. Other ECUs may still operate for a brief period after power is removed and continue to inject fuel as the engine spins down.

Either that, or the engine runs so rich when cold, that when more fuel is injected on the next startup, the latent fuel in the cylinders overwhelms the engine to the point of flooding.

Point is, running engines for short periods is bad, mmmm'kay.

The other point is, although it might not be the best practice, some (most?) engines seem perfectly capable of coping with such treatment. I've definitely run my engine for only a few seconds to move it on to ramps, then leaft it for several hours before running the engine for a few seconds to move it off the ramps again, without experiencing any problems, even if I then come back to use it when completely cold.

So is it _really_ that bad to run the engine for short periods, or is there a flaw in the design of certain engines?

Certainly, your suggestion that the ECU may cause the problem implies it's not that bad to run the engine briefly (at least as far as flooding is concerned, I expect increased engine wear does make it a bad idea generally), but merely should be avoided to work around the bugs in the ECU software...

John submitted this idea :

Condensation, absolutely not - it sounds like flooding. Basically engine has too much fuel inside it to be able to fire. The plugs will be wet with petrol, thus unable to ignite the mixture and need to be dried off. Just cranking it will do nothing, because it will just be adding more fuel and making the situation worse.

The usual trick is to crank it over with the accelerator pressed to the floor to make the mixture excessively weak, thus blowing the excess fuel out of the cylinders, but as others have said running an engine for such a short time is not good. Always aim to run the engine until at least reasonably warm.

Common on at least some BMWs - my 528 included. Floor the throttle and it will start, but won't idle properly for some time.

I'll second that. The old trick from the carby days usually works with EFI engines too. If flooding is suspected (engine turns over OK but won't fire, hot or cold), try holding the pedal to the floor without moving it from there until the engine starts. Give it up to 15 seconds before looking elsewhere for the problem.

Some ECUs provide additional help by interpreting the full-throttle start as an instruction to make the mixture less rich.

John

Dunno, but it was *guaranteed* with my Volvo 480, which was, without a shadow of a doubt, the most unreliable shitty piece of botched-together shit I've ever had the misfortune to own. If you started it and didn't drive it at least round the block, it would flood, and the only way to get it to start was to wait 20 mins. This was a bit unfortunate if you stalled it.

Did i say it was shit? Oh yes.

Ford ECU's interpret it as a 'flood start' signal and don't fire the injectors at all.

Be ready to jump out when it starts and shove fuse in before it dies.

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Nooo. Let it die. The cylinders will be clear of fuel and will start easy.