Last week 1988 Turbo R had a flat battery and I trickle charged it for a few days. I needed to move it and she fired up straight away and I drove it to the road around 100yards away. I came to start it around 4 hours later it fired straight up and died as I tried to move. I live onn a fairly steep hill so thought it was low on fuel so added a couple of gallons and exactly the same happened. Every time I crank it it starts immediately then runs for about 5-10 seconds. I got the car back to where I could work on it better and checked all the obvious and it still does the same. Changed the fuel filter in case I had dragged some dirt through but it was clean. Did a few more checks on it but nothing seems wrong. It feels like a fuel issue when it dies but I am not not so sure. If it was a pump then the fuel in the lines would not be sufficient to start it straight away, which it starts in two secs as I turn the key. However today I sat inside the car checking gauges and warning lights whilst cranking it and noticed a beep from behind the dash which in four years of ownership I had never heard. It beeps 5 times after I switch the ignition fully off. Is this an immobiliser or similar? I have never had a fob for the car, just a plain Bentley key. I am a skilled mechanic and do all the work myself but I am a little puzzled by this fault as its never happened before.