Hi,
at a rough guess I would guess that the earth lead, which is the black negative lead from the battery is either not making a good connection at the battery, or where it goes to the body it is not making a good connection there. Or if the batt has gone below 9 volts it wont matter how many jump starts you give it you will still not get 12 volts, make sure the battery reads 12 volts on a volt meter,or pinch ur mates battery to try.The fact you run out of petrol you have probably flattened it trying to get the fuel up to the carb,a tow start would probably get you going.
Paul Bale
May 2008