Had the same problem,,,and I've herd it's a comon one in them, I put a none return valve in the fuel line only took five mins anyone could do it,,,,£4 off the bay
This cured it for about a month,,,then it did it again,,so I bought another valve,,,this didn't work,,so I got a new fuel filter housing and filter,,,that cured it,,,for another month or two,,,then started again,,,feck. ME...
The next step was car cociane,,,,(easy start )that works everytime,,,
But mines the same park down hil and it's fine