?Fuel starvation on BMW 5 Series | The Back Room Archive | Back Room Forum

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Sun 7 Oct 2001 15:15

?Fuel starvation on BMW 5 Series - Chris

Anyone know of any common problems which would cause fuel starvation on a 1996 520i SE Touring?

Yesterday I drove the car about 10 feet and jacked it up to check the front tyre and brake wear. Then it wouldn't start, misfires with occasional bouts of running on all cylinders for a second or two. Have taken out and cleaned all six plugs, all looked OK, so seems like a fuel system problem. Is there an inertia switch somewhere and if so how do I re-set it? HJ's book mentions fuel pump relay problems in several places, where do I find it (the relay not the book)?

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Sun 7 Oct 2001 16:45

Re: ?Fuel starvation on BMW 5 Series - honest john

I think it's the cold running electronics protecting the bores and the cat from over-fuelling. You should never, ever start an alloy block BMW just to move it 10 feet. It needs at least 2 - 3 miles and preferably more for the cold running cycle to sort itself out.

HJ

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Sun 7 Oct 2001 17:10

Re: ?Fuel starvation on BMW 5 Series - Chris

Thanks for that. I agree in principle and would not as a rule mistreat any engine thus, but it has not suffered from occasional 'garaging moves' before. Any ideas on what I do with it now short of towing it to my BMW dealer and paying them a small fortune?

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Sun 7 Oct 2001 19:57

Re: ?Fuel starvation on BMW 5 Series - Andrew Moorey (Tune-Up Ltd.)

Had a similar situation on a 4 cyl 16v 3 series, moved to let another car off the drive then no start. Caused by the hydraulic lifters jacking up. The engine sounds like it is turning over with the plugs out and occasionally trying to fire up? Only remedy is to remove the plugs and spin up the engine to clear flooding after unplugging the injectors, replace the plugs and attach jump leads to a second vehicle. Replace the plugs and crank CONTINUOUSLY until it sounds more"normal". reconnect injectors and crank away till it fires up, hold a fast idle for 2-3 minutes or until it runs on all six then give it a long fast run. Sounds a bit barbaric but it works.

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Sun 7 Oct 2001 23:27

Re: ?Fuel starvation on BMW 5 Series - Chris

Sounds like exactly the same symptoms, Andrew, I was puzzled by the fast cranking speed, nice to know what the underlying problem is.

In fact I had given up, made an ON TOW sign and was all set to tow it tonight to the BMW dealers behind my wife's Corsa(!), but before setting off gave it one last try (without disconnecting the injectors) and after an age of cranking it finally spluttered into life. Of course I then did exactly what you did, kept it at a fast idle until I could get it out on the motorway to burn off all the clag.

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Mon 8 Oct 2001 09:41

Re: ?Fuel starvation on BMW 5 Series - John Slaughter

Had a similar problem on my Corsa the other day. For various reasons, it was moved a few yards a couple of times on the drive - not a usual occurence. Next day it just didn't want to start. The occasional cough and splutter, but that was it. In the end it started with full throttle to weaken the mixture and about 20 or 30 seconds continuous cranking, keeping the starter running during the times it fired. It eventually ran, but only with a few revs on and sounded very rough, as though it had only 2 or 3 cylinders. Once it warmed up it was fine, and has been no trouble since. I beleive this is the only way to start them under these circumstances. Hope it hasn't damaged the cat!

Regards

john

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