Vauxhall Carlton starting prob

This car (1992 Vauxhall Carlton 2.0GL)was bought by me as an MOT fail and was planning to sell it on ,but my dad fell in love with it and I have spend the last 10yrs keeping it on the road he is now 90 years old and he still loves (although he does not drive far)it and when I say keeping it on the road I mean what ever it costs but just lately things have been going wrong that are just doing my head in like dash board lights not coming on when you turn ignition on even though it starts and drives OK and fuel gauge not working even when the tank is full,but whats baffling me this time is my dad went outside and started it up to warm it up to go out he stopped it went in doors got ready went outside to start it again and it would not start he called me I checked everything I renewed the fuel filter and the throttle control and still wont start.There is a good spark and petrol is getting up to the engine or should I say up to the pipes up to the engine,but I don't think its getting through the injectors and wondered if it could be the fuel pressure regulator or the fuel pump not pumping enough pressure anyone have any ideas.