Power losses - Fuel Pump?

Hi,

I have had the following intermittent problem on my corsa (model details above) for around 14,000 miles now (2 years ish), and was hoping for some guidance on what the problem is likely to be.
The problem

Once the fuel level gets below around 20l, the car suffers power losses, of around 3-5 seconds then suddenly bursts to life again. The power losses usually occur when pulling away from standstill or on left turns (unusual yes but I can assure you that’s the case), if it’s really bad it occurs when driving at speed. I continue to apply pressure on the accelerator and it suddenly bursts back into life. The thing is, the problem comes and goes. For instance I have had the car running with 6/7 litres with no problems at all, on the flip side I have had 20l in the tank and the problem has started.

Putting fuel in the car has ALWAYS solved the problem. The other day I eventually got to a petrol station (numerous power losses on the way) with around 10l in, put 30l and the problem disappeared instantly, only to return when I hit 15l a week later.

For someone who knows little about cars I would guess at a fuel pump issue but would like to get other people’s opinion, could it be something else that a high fuel level would cover up? I tend to keep the fuel level high at the moment but it’s getting to the point where I need to address the issue.

Thank you.