S4 won't start

[Rossi]

Hi guys

After many years of faithful service my B5 S4 let me down last night. Cranked but wouldn't start.
Ran Vag-com on it today but there are no faults that seem relevant, so a couple of quick questions if someone could help me out.

1. Should the tacho move when cranking the engine before it fires? Mine doesn't.

2. When should the EPC light go out after turning on ignition? Mine stays on until after a second or so of cranking then turns off.

3. Should I be hearing the fuel pump running when I turn ignition on? I am not.

I'm suspecting engine speed sensor but don't have fault code for that and it's resistance tests ok.

Cheers
Rossi

[80 Vert]

All classic signs of the crank position sensor.

[Rossi]

Turned out it is a faulty fuel pump.

After much misdiagnoses and mucking around and an expensive tow truck home got it running again just by thumping the bottom of the fuel tank with a hammer...

Guess I need a new fuel pump though as if it's done it once I'm sure it'll do it again.

[mangusta]

just incase...get a can of crc engine start...if it wont start again,spray the stuff into the air intake for a few seconds...should start.cheers Mark

[ranton-inc]

just incase...get a can of crc engine start...if it wont start again,spray the stuff into the air intake for a few seconds...should start.cheers Mark

and how exactly will squirting engine start make his fuel pump run again....

[mangusta]

By the sound of it,it could be any thing,including an air leak causing it.My a8 has a similar problem...the engine start fires the motor causing the pressure to build up ,helping the pumps...just an idea anyway,its only 20 bucks but might help if it wont start in the middle of the night,another thing with these is if the tank is constantly run low,it will kill the pump sooner or latter,although this isnt the case here as the pump still goes..cheers Mark

[Rossi]

Salvaged a fuel pump from the remains of the S4 at Zebra parts Manakau so all sorted now. No longer have to drive around with hammer in the door pocket to jolt the fuel pump into life every second or third start!