2004 Audi A4 not starting

[TSmanzi]

Hi, my neighbours 2004 audi A4 manual is not starting and before he parked the car, he was involved in a small accident but he drove the car back to park it. The mechanic said only a light and radiator needed changing. And a while back he bought a petrol pump from used car spares shop . This car has not been used for more than 3 months now and with the battery changed,it's not starting but it turns . Now he called another mechanic and he was battling,he checked fuses,changed throttle valve and eventually the petrol pump. He removed the pipe from the pump and turned the key ON and feul came out. After that, he went under the hood and opened the inlet pipe and again turned key ON, we saw feul coming out again but he says the pump is the problem. He says it doesn't have pressure. Since petrol pump is expensive,I suggested that he gets another mech look at it . Is there anyone who might have a clue what is the problem.