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Question

My 2004 730d misfires on tick over but only if there is more than 1/4 tank of fuel. Any less than 1/4 tank and it runs perfectly any more and it misfires badly at tick over and low revs??

Submitted: 509 days and 15 hours ago.

Category: BMW

Value: $72

Status: AWAITING CUSTOMER ACTION

Optional Information:
2004 BMW

Already Tried:
BMW diagnostic service (SYntner) recognises the misfire, but can shed no light on its cause

Answer

Hello XXXXXXXXXX,
Please have your service center check the fuel tank vent system. Most likely this is clogged and causing fuel vapors when too full to cause the misfire (too much fuel will cause a misfire also).Boy ... those guys with the machines can only think if the machine tells them to !!!!!
Good Luck. Press the ACCEPT button. Leave positive feedback if I have been helpful. Thank you Dave

Accepts:
Expert:	SuperDave Auto
Pos. Feedback:	100.0 %
Answered:	7/1/2008

ASE Certified Technician

ASE Master Auto and Truck Technician, 24+ years shop owner

508 days and 14 hours ago.

Reply

Reply to SuperDave Auto's Post: Hi
I have run the car with the fuel filler off and it makes no difference. Perhaps this suggests that the solution is not to do with vapour release?

Posted by SuperDave Auto 508 days and 12 hours ago.

Info Request

Sure does. I may not be able to help you. Sorry and good luck.

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Question

My 2004 730d misfires on tick over but only if there is more than 1/4 tank of fuel. Any less than 1/4 tank and it runs perfectly any more and it misfires badly at tick over and low revs??

Optional Information

Optional Information: 2004 BMWAlready Tried: BMW diagnostic service (SYntner) recognises the misfire, but can shed no light on its cause