Gasoline odor outside the vehicle. No codes

[paulbert]

Hi,
I have owned my CX5 for seven years with no problems until recently. The car has 40 K miles on it. Lately, I've been smelling a faint to moderate gasoline odor outside the car after I fill up or even after driving for a good number of miles. Often, the fuel gauge Tik mark is one or two marks down from full and I still smell it outside the car; never in it.
I checked the gas cap to ensure that it does click after fill up and hooked up an OBD-2 scanner and have found no codes so that much looks good. I popped the hood and tried sniffing around the injectors and fuel rail but smelled nothing. It seems to be concentrated more on the driver side from the front door to the rear of the vehicle where the fuel door is located. There are no drive-ability issues (no surging, black exhaust) with the car and I do not smell fuel on the oil dipstick either.
Anybody have any ideas or suggestions? I heard that there was a recall for some CX5's due to a filler neck issue but this recall does not apply to my VIN.


Fast forward to today. Took the CX-5 to Stokes Mazda in North Charleston SC to have the smell investigated. When I arrived at the dealership I smelled gasoline fumes standing by the driver side rear quarter panel. Again, the tank was down 2 tics from full. I explained to the service tech what was going on and commented to him that I had just smelled the fumes minutes earlier. He wrote it up and I waited for the diagnostics report.

About an hour later, I received a video stream on my phone from the tech (not in real time) who explained that they were unable to locate the source of the fumes. He mentioned performing a pressure test (smoke test) of the fuel system but found no leaks.
When I asked his manager about probing for the leak with a fuel leak detector he said the dealership didn't own one. I mentioned to him that maybe his dealership should invest in one but he commented that they don't get many fuel leak issues,
LOL. So I haven't gotten to the cause of the issue but at least the dealership didn't charge me anything. I purchased a new fuel cap from Mazda on the off chance that it will solve the problem. Nothing like throwing money (albeit a small amount) at the problem

 

[HyFlyer]

What year is your CX-5? My first guess, beyond filler neck, is the gasket for the fuel level sender/fuel pump/filter area on top of the fuel tank.

If it were my car, I would run the fuel pretty close to empty, then fuel it with only about 4 or 5 gallons. Note any fuel smell right after fueling. That should tell you if it's leaking from the neck on it's way to the tank. If that checks out, fill 'er all the way up and see if you notice the smell. If so, I believe the top of the tank area is suspect. Someone will be along with a description on how to get to that from under the rear seat to see if it's wet there. Or I'm sure there's youtube video.

Careful now, don't blow yourself up or catch the garage on fire

 

[paulbert]

What year is your CX-5? My first guess, beyond filler neck, is the gasket for the fuel level sender/fuel pump/filter area on top of the fuel tank.

If it were my car, I would run the fuel pretty close to empty, then fuel it with only about 4 or 5 gallons. Note any fuel smell right after fueling. That should tell you if it's leaking from the neck on it's way to the tank. If that checks out, fill 'er all the way up and see if you notice the smell. If so, I believe the top of the tank area is suspect. Someone will be along with a description on how to get to that from under the rear seat to see if it's wet there. Or I'm sure there's youtube video.

Careful now, don't blow yourself up or catch the garage on fire

Its a 2014 with a 15 gallon tank (AWD). So run the tank down to maybe an 1/8 of a tank then put in 4 gallons. If I don't smell anything then that eliminates the filler neck. Continuing on filling it and If I smell it as I near the top of the tank then its probably the gasket for the level sensor/pump/filter assembly. OK, makes sense I'll give it try. Thanks

 

[cz5gt]

you can lift the rear seat cushion and take a look if you suspect the gasket of the fuel pump assembly. Although you said you smell it from outside.

If there are leaks or smell from the gasket inside it would be noticeable.
Have to lift the rear seat (pump is at the drivers side) and then remove a metal plate which sits on top of the fuel pump assembly.
The pump actually sits a bit lower than the top level of the tank.

 

[paulbert]

you can lift the rear seat cushion and take a look if you suspect the gasket of the fuel pump assembly. Although you said you smell it from outside.

If there are leaks or smell from the gasket inside it would be noticeable.
Have to lift the rear seat (pump is at the drivers side) and then remove a metal plate which sits on top of the fuel pump assembly.
The pump actually sits a bit lower than the top level of the tank.

I'll check out some youtube videos on removing the rear seat cushion but I don't smell anything inside the car. So the fuel level sensor/pump/filter assembly is accessed through the passenger compartment. Yeah, it would surely stink inside the car if the gasket were bad.

 

[paulbert]

is the complete top of the tank exposed to the passenger compartment or just the fuel pump assembly?

 

[HyFlyer]

Its a 2014 with a 15 gallon tank (AWD). So run the tank down to maybe an 1/8 of a tank then put in 4 gallons. If I don't smell anything then that eliminates the filler neck. Continuing on filling it and If I smell it as I near the top of the tank then its probably the gasket for the level sensor/pump/filter assembly. OK, makes sense I'll give it try. Thanks

I would put the 4-ish gallons in a go drive around on your normal life and see if you notice any odor. Then, when you run through that (100 or so miles), fill it all the way up.

If you notice an odor right away after adding the 4 gallons, that would point to the filler neck.
If the gas odor goes away later and doesn't come back till you fuel again, --> filler neck suspect.

If you don't get any odor right away or while driving that low fuel level out, that would rule out the filler neck and actual fuel lines from the tank to engine.

If all of the above checks out, Fill all the way. If odor returns, I would suspect the pump assembly gasket.

... and one last edit question ... do you typically "top off" the tank or just quit filling after the pump clicks off?

 

[cz5gt]

is the complete top of the tank exposed to the passenger compartment or just the fuel pump assembly?

I think only a hole in the metal frame through where the pump is immersed into the tank. Its been a while since I looked so have vague memory.

 

[HyFlyer]

If there are leaks or smell from the gasket inside it would be noticeable.
Have to lift the rear seat (pump is at the drivers side) and then remove a metal plate which sits on top of the fuel pump assembly.

Maybe it wouldn't be noticeable inside the vehicle. I believe the little metal cover has a sealant on it. Wouldn't be a very good design to have gas fumes enter the cabin.

 

[HyFlyer]

Here's a clicky for a video by one of the forum members (fuel tank fun starts @ 2:42 ) ....

https://youtu.be/ICUiqXrPsh0?t=162

 

[cz5gt]

Maybe it wouldn't be noticeable inside the vehicle. I believe the little metal cover has a sealant on it. Wouldn't be a very good design to have gas fumes enter the cabin.

its possible and seems logical as you mention. I have never removed it.

 

[paulbert]

I'll check it out and give some feedback after the holidays. Thanks for the really useful information.

 

[paulbert]

Here's a clicky for a video by one of the forum members (fuel tank fun starts @ 2:42 ) ....

https://youtu.be/ICUiqXrPsh0?t=162

excellent video by the way.

 

[PTSanchez]

We see mention of the gas cap, but nothing about its O-ring seal: the cap can still "click", but the O-ring can be faulty. Suggest inspecting it.
R&R if the O-ring is cracked, crushed, hardened or collapsed.
Be advised that one may have to buy the entire cap assy - just to score the O-ring.

Lately, I've been smelling a faint to moderate gasoline odor outside the car after I fill up or even after driving for a good number of miles.

 

[paulbert]

Isn't the o ring seal in the gas cap? If so, I replaced the cap assembly with an authentic mazda part and still continue to smell the fumes on the outside of the vehicle along the driver side passenger door and down toward that rear quarter panel where the gas cap is located. The smell goes away hours later. I never smell it inside the car with the windows up. I suspect it may be those charcoal canisters or plumbing associated with the evaporate emissions hardware. It never throws a code.

It's like the contents of the canisters gets dumped but on would think there should be a few codes dedicated to that hardware.

 

[CX5Nut]

This thread is from 2021. I wonder if the OP ever found the cause of the fuel smell.

 

[sm1ke]

This thread is from 2021. I wonder if the OP ever found the cause of the fuel smell.

The OP just posted yesterday. They still seem to have the issue described in the original post.

@paulbert did the testing suggested by @HyFlyer give any notable results?

 

[LeSheep]

different engine (mine is 2.5T), but I have the gas smell from time to time and now got a DTC P144C. I guess yours might be related to the emission control system as well. Just a possibility.