stalls then not starting

[tommy1]

hi
wondered if anyone can help
i have just bought a 1.4 petrol 2007 berlingo van with 70k on clock a few days ago,drove it 80 miles home and ran like a dream,next day went out to start the van and started fine then drove about 20 miles then at some traffic lights it stalled so tried to restart and wouldnt start (turns over fine)so called the aa but by the time he arrived it started,while i was sitting in the van with the ignition on waiting for the aa i heard the fuel pump buzz then i tried to start and it did but while it was ticking over for about 10 minutes it stalled again and wouldnt start but after few minutes i heard the buzz of the fuel pump then it started again,aa man towed me home and said could be a ecu fault or faulty fuel pump any ideas anyone,anyone had any similar experiences,i thought it could be a fuel pump relay but been reading a bit and they seem to be run by the ecu ??
thanks

update
just put a new crankshaft sensor in and made no difference