E46 320D - died !

[red997]

morning all;

my trusty 320d touring decided to die on me last night;
45 miles in 40C on the M25, no problems at all, no indication of any faults, car running normal, as per usual.
Pulled off M25, onto slip road, tootled up to lights, and as the car came to a halt, it stalled & stopped running.
Nothing could coax it back into life.
Managed to get it off the road & sorted recovery (only 3 miles from home thankfully)
Quick check again this morning - turns over very healthily , but doesn't start.
No warning lights on dash - all normal.

So - suggestions where to start ?

(2003 320d 145K miles)

[helix402]

Read DDE fault codes, check if has fuel in.

[red997]

fuel gauge was showing half full, which ties in with mileage vs last fill up

Going to read the codes tonight

Are fuel pumps a common failure on these cars (age & mileage ?) ?

[Touring442]

These have an in tank pump AND an underfloor pump. The HPFP rarely fails but it can. A faulty injector reduced rail pressure to the extent that the pressure sensor tells the ECU not to operate the other three.

On the upside, used parts are cheap enough.

[red997]

OK - so I got me spanners out;
first things first - fusebox - blown 20A fuse for 'fuel pump'

in tank pump first (as it was the easiest) - removed connector, replaced fuse, blew instantly
Also checked the fuel pump relay - works fine

So, from that I deduce that the under body pump is fecked

only £30 so worth a punt

[mercedeslimos]

Common on the MG ZT / Rover 75 that uses the same M47. Replaced both electric pumps last year, under bonnet pump was whining horribly and the in-tank pump was dead. Drove much better afterwards!

[Touring442]

E90 and 1 Series M47N diesels ditched the stupid underfloor pump and just fitted a higher pressure lift pump in the tank. The E39/E46 twin pump system was just bizarre.

[red997]

pulled the elec connector from the under body fuel pump - fuse no longer blows.
When the new pump gets here I suspect we may be in business... fingers crossed

[red997]

just to conclude this - it was the underbody fuel pump that had failed (seized & short circuit, hence the blown fuse)

£29 later and a bit of my time under the car all fixed and running again.
might be my imagination but seems smoother at idle