Gas leak only after fill up - bad gas cap?

In some cars, a leak in the EVAP system won’t let you fill the tank - since the nozzle needs to sense vapors being pushed to the fill pipe to keep the valve open.

Got access to a smoke machine? Smoke might be your best friend here.
 
In some cars, a leak in the EVAP system won’t let you fill the tank - since the nozzle needs to sense vapors being pushed to the fill pipe to keep the valve open.

Got access to a smoke machine? Smoke might be your best friend here.
No, I didnt need to, took off the back seat and found the cover of the fuel pump housing was rusted and wet with gas. Apparently these are common on some Mazda's, the dealership changed a few. They had to change the rusted cover (ring) and rubber seals, and also a part of the fuel pump assembly which is called the sending unit. The most expensive part was the sending unit around 110$ CAD, the rest of the parts were around 20$ each. Took 45 minutes to an hour to do the job. No more gas leaks, no gas smell, everything is back to normal.

At fist, I suspected the charcoal canister, but it was all dry. I could smell gas in the car, that's where I clued in that it could be under the back seat, and it was. No problems ever since. It's the only part I had to replace in six years of ownership and 220 000 km, other than brake pads and disks, filters, and spark plugs, oil, few bulbs.
 
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