BMW E34 cold start problem

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Fri 9 Dec 2005 10:25
BMW E34 cold start problem - johnb
Help please
1990 520i with 88000 mls and full BM service history,for the last 3 months is very difficult to start first thing in the morning. 3 visits to BMW and 3 further visits to BMW specialist has failed to resolve the problem,in fact it is getting worse.
At first they said it needed a full service - no improvement,then it was a faulty ECU unit,had this replaced - it did not resolve anything,then they replaced the thermotime switch which apparently controls the cold start injector - no difference at all,and finally the filter on the fuel line (it must be partially blocked)the car has still got the original problem.They now admit that they do not know what the problem is.
It will eventually start after several attempts and smells strongly of petrol and then it is fine for restarting, throughout the day it runs well.
Somebody out there must have had this problem and know the answer I am sure it is something relatively straight forward. Help Please.

John B
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Fri 9 Dec 2005 10:30
BMW E34 cold start problem - Hamsafar
Common problems are the small delivery pump in the fuel tank not working and leaving the high pressure pump to draw fuel from the back of the car (not what it is optimised to do which is high pressure injection)

Another problem is the RUN/START relay in the fuse box having 'dry' solder joints.
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Fri 9 Dec 2005 18:09
BMW E34 cold start problem - elekie&a/c doctor
If this is a 520 12valve engine there is a known cold start/overfuelling situation for which there is a modification to the engine coolant temp sensor & Ecu wiring.
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Sat 10 Dec 2005 13:37
BMW E34 cold start problem - johnb
Ishok Leyland
Thank you for taking time to reply,also anybody else who has sent in suggestions as to what might be causing the problem.
The small delivery pump has already been checked and is ok, but the RUN/Start Relay sounds promising however I have had a look this morning and whereas each fuse is numbered and named the relays are not, forgive my lack of technical knowledge but how do I know which relay is the run/start relay.
Thank you.
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Sat 10 Dec 2005 15:01
BMW E34 cold start problem - Peter D
You say there is a strong smell of petrol when it starts, this makes me think it has fuel so what about a spark. Grap a spare/old plug and connect it up suitable earthed, then next morning crank it over and see if you have a spark, may need 2 people. If you have a spark then it is not conclusive as the timing of the spark could be complely wrong but if you have no spark or a yellow lazy one then it's a good start. I've changed a Crank Positon Sensor for this type of fault, remember the first start of the day is always slower, cold oil, cold battery, always slower and the sensor may not be putting out enough signal for the ECU. Having said that the fuel and Ign system tend to use the same signal source. Another good test is on the first start of the day Bump start the car, either get some help, 2 more people, or do you live o a hill, and bump start the car Ign on second gear get some speed up and drop the clutch. If it starts straight away then a CPS or Cam PS could be the problem. These do not get reported by the ECU during start up on many cars, not sure about BM's. Regards Peter
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Tue 12 Oct 2010 14:10
Zafia 2000 cold start problem - keithtash

my 2ltr zafia 2000 has started being a problem when trying to start from cold . This is an intermittant problem as sometimes the coil light shows on the dash it starts normally , but sometimes the coil light will not show and then it turns over at least 9-10 times before it fires . is this possibly a loose wire , if so where is it located , please help this is causing me a lot of problems ..thanks..keithtash

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