fuel pump

[waynekid]

hi all, 98 polo i've had the erratic idle and used a good quality (fuel added) cleaner to get rid of the residue built up in the throttle body, that seemed to cure it, but a couple of days after this was sorted the car cut out altogether and wouldn't start. Breakdown said it was a problem with the fuel system and to possibly change the fuel filter, so i did and it was fine for about 30 miles then it died on me again. this time took it for a diagnostic he said to replace throttle body, so i bought a used one and fitted it and still won't start, again breakdown said fuel system possibly pump. Can anyone out there please help, where is the Fuel pump and how can i diagnose the problem. Thanks in advance