Unusual noise at start--What is it??

[Jack50]

Hello,

I recently purchased a 1995 Polo (petrol engine) and have noticed a unusual noise upon starting the engine from cold. As the engine is cranking, and immediately before it is running, there is a brief single-tone noise that lasts about half a second (the sound is about as loud as the horn would be if the windows were up and you were travelling at speed). The sound is coming from the front of the car and does not continue longer than half a second, nor does it repeat itself. The noise is consistent each time it occurs.

If the car sits for days in the garage, it can be a bit sluggish to start, and there can be a minor smell of petrol after starting. I have checked under the bonnet for leaks and I don’t see any.

Does anyone have an idea of what this noise may be?

Many thanks,

Jack