So my roadster 2012 cooper s which has the 2nd gen r56 platform (N18), has a fuel smell every now and then.

Ive noticed the smell lately on a cold start. It smelt really strong at the back of the car on the drivers side this morning.

Ive also had the smell after some heavy cornering. Also had it happen on a long drive just cruising around. Its a convertible so the top is down when I drive. Although I swear getting up to speed once on the highway it almost smelt like the smell was coming out the vents. But perhaps it was just recirculating the smell already in the cabin.

The fuel smell is very intermittent.

Has 2 months warranty left from the used car dealership. Took it in today and they couldnt see any leaks. But they didnt take anything apart to look. Just looked around the engine bay and under the car. They suggested to come back with a full tank of fuel and they will corner it hard to see if that results in a leak. They also said that next time they will pop the back drivers side plastic wheel arch off and have a look at the tubes there as well in case they are leaking.

Does anyone have any ideas around this issue that I could pass on to the mechanics? Especially things I should be getting them to check that could give these symptoms?

Thanks

 

the only thing i can think of is your gas tank cap...do a sniff test around there and see if you can smell any thing. make sure the cap is tight and examine the rubber gasket. also, are you loosing gas faster than normal? or just when the car is running you smell it?

 

Just when the car is running I can smell it.

I had a sniff around the cap but it seems its the whole back under area of the car that you get a fuel smell. I notice it in the first minute after a cold start then the smell seems to go away. And then occasionally when Ive really pushed it.

 

My car sometimes does the same...

 

Mechanic found a couple hundred fault logs for the thermostat not working. Says that could cause the smell because it makes the car run rich because the car thinks it is zero degrees. Im in warranty because it came with 3 months warranty from the dealer. They agreed to cover the replacement of the thermostat. They said its an $800 job. Sure the aussie dollar is worth only 70 cents to a USD but still pretty pricey repair. Glad we caught it.

i found this info by googling:

"Modern EFI engines have a cold start system usually employing a high capacity single injector that delivers an extra measure of fuel when the engine is cold. not warm or coldish but cold. The injector is controlled by the engine ECU to operate for a very short time. After the engine has started it will then operate at higher than idle rpm on a air bypass valve until the coolant temp reaches the ECU determined setting and then the valve will slowly close. The fuel smell i suspect will likely be the residual fuel the engine has not induced inside the inlet manifold during a cold start. This will eventually evaporate with air flow but you should never have any fuel smell outside the engine. This is a basic ADR requirement."

 

Rear behind driver? Low pressure fuel pump + fuel level sender, and the service cover over it, is directly under the rear seat cushion in my 2011 R56 S hardtop...

And a fuel level sender unit + container holding the fuel filter is also under a service cover, directly under the rear seat cushion, on the passenger side.

 

No more fuel smell since thermostat replacement

 

Did not expect that but WOOOOO