2003 Volkswagen Golf starting problem

i have a 1989 vw citi golf with a 2003 1400 fuel injection engine. it is giving me starting problems. you can turn the ignition on and the engine will start but after 2 sec it sounds like a relay kicks off then the engine automatically just dies. we have replaced the fuel pump a few days ago thinking that it might be of a low fuel pressure but the problem still continues. the starter is still in good working condition and we also replaced the throttle body with a new one. please help, i'm feed up with the problem and don't know what to do or what to check for.