You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
’55 plate BMW E91 320d, 193k miles
Driving home to Sheffield from the other half’s parents in Suffolk last night, last leg of the journey on the M1, just south of Nottingham, happily pootling at 70 dead on cruise control, a big “engine death” symbol pops up on the dash, followed a couple of secs later by the “get me to a garage NOW” one. Car starts to lose power, then engine quits all together and we fail to make it to the next refuge on the smart motorway (gods, those things suck), so ended up ditching tight to the armco and hop out.
(to be fair to Highways Agency and the AA, we get picked up and moved to the refuge, then recovered home pretty efficiently.)
The AA guy plugs his computer in and gets a whole bunch of fuel pump/fuel pressure errors, so the first thing I check this morning is the pump fuse. Very definitely blown. Stick a new one in and the car starts and runs very happily. My code reader says the pump is sitting there at 8.5V sucking 8A +/- a few 0.1, on the 20A fuse. (both V&A match the desired figures). No errors to be found.
So why did the fuse blow? Do they age? Can pumps overheat? I can chuck cash at a new fuel pump, but would rather not unless I actually need to. The AA chap said I should be able to hear the pump running, but even with the seat squab up and the access panel off, so I can see the top of the unit, I can neither hear nor feel anything – but it must be working because the engine is running…?
Advice gratefully received!
Thanks.
(2nd attempt at posting this after the first got eaten “403 forbidden” <<sigh>>)
Ime with MB and Volvo there are multiple pumps. As your car is rwd there's possibly 2 in tank pumps and one up front.
Not familiar with the n47 engine to know if you have a mechanicsl hp pump bolted to the head, but at 8amp.i guess it's electric only.
And chuffing expensive.
Might be starting to fail and extended run time has melted the fuse.
Unless you have a multimeter and can check the resistance with a known good one, carrying a pack of fuses till it quits altogether may be the way forward
Older m57/m47 experience here
those cars had 2 pumps, lift pump in tank that supplies the main electric pump under passenger seat which then supplies 3? bar of pressure to the injection pump.
Later injection pumps are less reliant on the feed supply, in fact i think my m57 would run with no supply pumps when started.. just not from cranking. So i'm not sure i you have both sets of pumps.
My old e39 had a little "feature" if the intank pump failed it would keep running. BUT only pick up the first 3/4 tank of fuel, after that she'd suck in air and die.
Failing pumps usually get noisier prior to total failure
The fuse won't just blow willy nilly.. as motors wear they demand more current, for peace of mind... and not much money i'd be changing the pump. But be sure there is only one. If it's not been done at 193k it probably warrants it
Google tells me that you have a 2 pump system.
1 x high volume low pressure pump in the tank that feeds 1 x lpw volume very jigh pressure pump that is engine driven up front.
Resr pump cheap and easy to diagnose, front, complex and expensive.
Rear pump will run on ignition and you shoild feel a vibration when you touch the fuel tank
Front pumps die from the silly b5 extended oil drain schedule, plus wear and tear
Thanks all.
Its an M47T2 lump.
Codes off the AA man's reader were:-
4560 - Rail: Plausibility pressure control deviation positive
4590 - Rail: Plausibility pressure Minimum pressure not reached
49B8 - CAN message: Electric fuel pump missing message
4B90 - Rail pressure regulation: Via component <Fuel presssure control valve> Pressure increase too low.
If the highpressure fuel pump is engine driven, and its the electric fuel pump that was missing, logically that's the tank one? (If it was the engine one, it wouldn't be solved by a fuse change and presumably as its driven by the timing chain, then it would be mechanical failure equalling probable engine death)
I've just been and had another poke. Ignition on/engine off - nothing. Ignition on/engine on, with the access hatch open you can hear the pump going, but its whisper quiet and barely audible over the engine daggadagga unless you have an ear reyt close to it.