Gas Smell

[kakashi169]

In the morning when I start up my car. I notice a gas smell coming from the vents. Anyone know why the smell is coming from the vents? Could it be a bad seal of some sort or exhaust leak?

Thanks.

[brettbimmer]

Hmmm...are you sure that it is coming through the vents and not otherwise inside the car already? I ask as I believe that our fuel pump & fuel feed lines are under the rear seat cushion, as in many other Bimmers. If by chance there was a leak there - either from the fuel pump gasket or feed line, I wonder if starting the car in the morning is just circulating the smell from under the rear seat, if there happens to be a leak there. Otherwise I would double check all fuel feed connections under the hood to be sure that there are not any obvious leaks. Also, is this smell every morning, or did it just happen after recently topping off your tank the evening before - ie-overflow?

[alexandre]

It's been happening too on -15F mornings... But only when idling to defrost the windows. Went away after. I figured it came from outside and was no big deal.

[LivesNearCostco]

I think modern engines run rich during cold startup and cold cats don't burn up all the extra gas. Maybe some unburned gas is just drifting forward and getting sucked into the vents? My old Saturn stinks in the mornings until the cat warms up but I only smell it if I idle in place or back up through the exhaust.

Right after I got my ZHP the fuel pump gasket was leaking and the inside of the car smelled like gas all the time when the tank was full.

[nike001]

I think modern engines run rich during cold startup and cold cats don't burn up all the extra gas.

This. The engines have their own 'choke' so they dump in extra fuel to get things going. Definitely more noticeable in the cold, whether it be that the car is adding more fuel for the cold(er) start or it's the cold that has you smelling it.

[Bimmernut2]

Ditto on the gas tank top seal & plastic cap on left or right side. Is you gas tank full? I had a small crack in my cap that was on the drivers side. The gas smell was there until about 3/4 full. Remove the rear seat bottom, then lift the black insulation material to expose the (2) units. Look for signs of fuel leakage on these "white" top caps that hold either the pump (right side I think) or the fuel level sensor (left side) They are prone to cracking & allowing a small amount of gas wix to the top of the cap. Once I located the one cracked & leaking, I cleaned it very good, used some sand paper to rough up the surface & then used some hot glue to seal the top area. Solved my problem.

[BimmerWill]

Also check your electrical connections on the fuel pump and sending unit themselves. A year ago or so I had a pretty major leak that would only occur above half tank. Many hours later and failed attempts at finding a leak after dropping the tank I discovered that one of the leads on the top of the fuel pump had somehow shorted out gotten hot and melted the plastic around it allowing gas to seep up out of the top of the tank.

Very scary considering my only cue to something being wrong was the gas leaking out. Car and fuel pump still worked no problem even with the lead no longer plugged into the receiver.

Not sure if this has been a common problem but worth checking out. Would even recommend it to anyone to take a look at theirs next time. Would hate for a spark to occur somehow in such a situation...

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[kakashi169]

Hi Guys

Thanks for the replies. I took the car to a shop and found out what was the problem. The shop tells me its a bad MAF sensor. I tried cleaning it a couple of weeks back and it worked for a while but now the CEL came on and I am going to change it.

Will keep you guys posted.