[superlift77]

Hey guys another annouying cold start issues, just trying to get some straight answers for the sypmtoms my car is having, I have searched and found others with "like" symptoms but everyones is different so here goes...
2001 525i 5 speed, 98k
When its cold the car will crank normally and the battery is good, cranks over fast and strong but doesnt even try to start, I tried starting fluid and it will start the car but will not stay running so its not a spark issue, Had it towed to a mechanic(bmw) who said the fuel pump was getting low voltage so he replaced it(Was out of town no other options), and when he did that car started fine when I picked it up but the temperature was also about 70 degrees unlike when I have the no start issue when its 20-40 degrees.( I dont know where or when he diagnosed the FP issue)

So regardless of a new fuel pump I am still having the same issues, but if I hold the pedal down and wait 10-15 secs and try the car will start, idle rough for a min but smooth its self out..

Any ideas or any one having these same issue?


I was told bad cps(but I researched a bit and if a bad cps is the culprit and not sending signal to the ecm it will not turn on the FP!, but it also wont send spark!) so I dont think its that

Bad Vanos seals? I Have not unplugs the connector to the vanos to see if it starts with out it(sets it to default mode? from what I have read)

It has new sparkplugs and coils are all operational

NO CEL! whats the point with all these's electeronics/sensors that the car cant even tell me why it wont start!!

Thank you guys, I posted about a month ago with similar problem but it was miss firing, it was a leaky valve cover gasket, replaced that no more miss and the cold start issue went away it seemed, but it has not been that cold since then, its a bit colder now

 

[superlift77]

Update: car won't start this morning, could not hear fuel pump turn on at all,
I unhooked the vanos connector and did not change anything,
The car eventually started, I left the key in it for about 5 mins on the on position, and starts now
I don't get why the fuel pump does not get a signal to turn on only when's cold????(new pump, and still same symptoms)
Any help is very appreciated

 

[JimLev]

If the fuel pump was getting low voltage I don't know why the mechanic would be changing the fuel pump, other than he wanted to charge you more money because he knew you were out of town and didn't really know how to troubleshoot electrical problems.
I would have started by checking/changing the fuel pump relay.
On your car it should be behind the glove box. Earlier cars had the relay above the battery.
When you turn the key to position 2 the pump should run for ~2-3 seconds to build up pressure and then shut off.
When you turn it to crank it should start running again.
If the crank sensor doesn't detect that the engine is turning over it will shut down the fuel pump.
Your fuel filter must be OK because it starts and runs OK when warm.

 

[superlift77]

Your probably right about the mechanic he did put in a new FP from BMW for 400, not bad but unecessary but it is what it is.
Going to go get a new relay, Thxs for the location it's not in the trunk or under engine compartment like I have read in other posts,

Thank you for the response !

 

[champaign777]

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