[SOLVED] 635 Cranks but stalls immediately

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TomMan7531
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[SOLVED] 635 Cranks but stalls immediately

Post by TomMan7531 »

Hi,

So my two week old 635csi has stopped starting, after letting it sit for a week with the dashboard off the car all of sudden wont start. It was cutting out before even sometimes when driving but now it starts but wont hold the revs and stops straight away.

Having disconnected the battery while doing dashboard wiring I wondered if it was an immobilizer on the 13 button on board computer but having followed the below guide I reset it and still nothing.

http://blog.bavauto.com/2973/bmw-obc-an ... 0-e32-e34/

When a mechanic came round he sprayed some fuel into the engine and it started fine, though died straight away when he stopped. He also checked the fuel pump fuse (fuse 11) and seemed to have no power running through it so I presume this is a fuel issue rather than ignition which I have been reading.

Hope this helps, I appreciate the reads and any responses. Tom
Last edited by TomMan7531 on Thu Mar 30, 2017 6:50 pm, edited 1 time in total.
1987 BMW 635CSI Auto, Royal Blue, Cream interior, daily rust finds....
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hornhospital
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Re: 635 Cranks but stalls immediately

Post by hornhospital »

Did he or you test the fuel pressure? Starting on starter fluid then immediately dying indicates the crank sensors are good or it wouldn't fire, and if the plugs are firing the injectors probably are, too, which leaves a non- working fuel pump. Bypass/jumper the fuel pump relay and see if the pump will run. If it does, try cranking it with the relay bypassed.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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Brucey
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Re: 635 Cranks but stalls immediately

Post by Brucey »

does it only fire using starting fluid? If so then you have no fuel pressure.

However if it fires when cranking (no starting fluid) but then dies, this indicates you have fuel pressure, and CSI function, but the main injectors are not firing. This happened to me and it was a bad main relay.

cheers
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TomMan7531
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Re: 635 Cranks but stalls immediately

Post by TomMan7531 »

Hi,

Starter fluid being in the aerosol can which you spray straight into the engine...then yes, spray that in and it starts and ticks over and when that continues to spray it works fine, as soon as the guy stopped the car stopped. On its own steam if you leave it sitting it will start but then dies straight away, when this happens you can smell petrol from the outside, try it again straight after it normally will just crank with no sign of life.

I will add also that if you put it in sport transmission and crank it then it resets to the middle being eco, not sure if thats normal...I did read somewhere saying loose wiring there can affect it.
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Re: 635 Cranks but stalls immediately

Post by wattsmonkey »

Auto selector should click back to Economy, yes.

Starter inhibitor for autobox not fault: it wouldn't crank.

As per above: relays are obvious place to start - fuel and main. Either follow Brucey's guide to jumping them (do a search for relays on here) or substitute (horn relay is same as fuel; get a spare main relay in any case!)

If it will start and run for a second then fuel must be getting there! Possibly only running on the cold start valve, with injectors not kicking in.
"Most of it necessary; all of it enjoyable." LJKS
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TomMan7531
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Re: 635 Cranks but stalls immediately

Post by TomMan7531 »

Yeah will do, I have already seen Bruce's breakdown of the relay switches so Ill play around with them and update.
1987 BMW 635CSI Auto, Royal Blue, Cream interior, daily rust finds....
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TomMan7531
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Re: 635 Cranks but stalls immediately

Post by TomMan7531 »

So Ive pulled both out, From what I can read the orange one which i'm guessing is aftermarket is the fuel relay and the other one is original and when shook you can hear it rattle, hopefully thats gone and I just need to source the part, hard to find in UK though so might have to call BMW
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Re: 635 Cranks but stalls immediately

Post by wattsmonkey »

That's right: orange one is fuel. Not necessarily aftermarket, later relays orange.

Defo dealer to make sure you've got the correct main relay - there's a white one which does the job but always seems a bit suspect!
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
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TomMan7531
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Re: 635 Cranks but stalls immediately

Post by TomMan7531 »

Ok cool, I',m heading down the dealer tonight so will ask, hopefully the rattle its making is the sign its dead
1987 BMW 635CSI Auto, Royal Blue, Cream interior, daily rust finds....
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TomMan7531
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Re: [SOLVED] 635 Cranks but stalls immediately

Post by TomMan7531 »

So thanks for all the help as it would seem changing the diode relay (the silver one) worked a treat, just went for a spin and all seems fine, if in the UK worth knowing that relay cost me £42 with VAT from BMW.

Thanks again for the help :)
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Re: [SOLVED] 635 Cranks but stalls immediately

Post by wattsmonkey »

Excellent!

I think most sixers will have experienced this relay going bad. I'm not alone in carrying a spare in the glovebox next to the Midget Gems!
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
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Re: [SOLVED] 635 Cranks but stalls immediately

Post by slofut »

Good job Tom! Thanks for the follow up, closure helps members in the future with similar problems.
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