1995 Audi A6 2.8L V6 Petrol

Hi, recently one of the pipes/hoses that is part of the suction jet pump has corroded and failed. The vehicle is an 1995 audi a6 2.8l v6 fwd, and ever since replacing this hose, the car won’t start but crank for ages. If the key gets turned to the ON position and then to the START position, it will just crank.However if one turns the key all the way to START immediately, the vehicle will start for 1 sec. and then die again.
any ideas?