Hi I've been working on my mates '96 Vectra 2.0l estate which failed to start after being left for a few days in the cold. After replacing 2 faulty glowplugs and priming the fuel system by pouring fuel into the out pipe from the fuel filter to the injector pump, it started and ran ok . Left it for half an hour , still started ok . The next day my mate couldn't get it to start. Any Ideas please? TIA Mark