Could somebody help with this?

When you insert the key in the ignition with a stock ECU, you can hear the fuel pressurize and then cut switch off until you push the start button. Why does it work this way?

Now, with some aftermarket ECUs - when you turn the key, you can hear the fuel pressurize the lines but then it doesn

 

This is pretty common on all modern day stock vehicles. When the car sits, it's possible that the fuel pressure in the fuel rail "bleeds" down a bit, so to bring it back up, the fuel pump goes into a "pressurize" cycle as soon as the ignition is keyed on. If you don't start the engine, there's no point in keeping the fuel pump blasting full tilt, so it cycles down or off till the demand is there. In some cars, the initial "power up" may even be higher pressure than when the engine is being operated. Then it steps down for normal function.

 

Okay - but if the fuel pump keeps going - can it be detrimental to the engine?

Thanks for the reply though.

 

there is usually a return line on the fuel rail that sends the excess fuel back, so no I don't see how it can be detrimental.

 

Many thanks

 

The only potential problem is leaving the key on without starting the engine and killing the battery.

 

Thanks Slow I usually start the car as soon as the check lights go out which is usually around 2 or 3 seconds.