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I have a Ford Focus MKII (British market) with the 1.8 Duratec Engine that is very hesitant starting when warm.

The starter cranks powerfully but the car will only come to life when pumping the accelerator, sometimes it'll start but at very low revs (until I pump the accelerator).

In about 20% of warm engine scenarios it doesn't need this treatment but it never occurs when the engine is cold.

Through research I've heard about something called 'vapor lock' which appears to describe this - the remedy (drop the accelerator at the same time of killing the engine) seems to resolve the issue for the next startup.

Do I have vapor lock? Any pointers of how to prevent this properly?

Zaid
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m.edmondson
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1 Answers1

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In fuel-injected systems, hot-start problems indicate that the fuel line is unable to maintain pressure.

This could be due to a few things related to the fuel supply line, including:

  • a leaky fuel injector
  • minute cracks in the fuel line which leak fuel when under pressure
  • a bad non-return valve in the fuel line which is allowing pressurized fuel to flow backwards

The reason why this happens only for hot starts is because the fuel is more likely to vaporize as temperature increases. In order to avoid vaporization problems the fuel lines are expected to be pressurized during a hot start.

Zaid
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