One problem related to other fuel system tank mounting has been reported for the 2011 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2011 Hyundai Sonata based on all problems reported for the 2011 Sonata.
In the beginning of may, 2016 at 105k, I started the car and I made it down the street and the car stalled in front of a stop sign. The engine, oil, battery, and esc lights came on. I turned off the car and tried to turned it back on and it wouldn't start. I got the car towed to the dealership and they said it was going to cost $1000 to replace the fuel pump so I took to another mechanic and he replaced it with an aftermarket fuel pump for $375. Got it back and it ran great. 2 weeks later, on my way to work I had a full tank and I drove about 10 miles and my full tank went to a half tank and it was saying I had 289 miles left then said I had 270 and then went to 290 miles left in less than a minute. I got off of work and the car started, but stalled in the middle of pulling out of the parking spot. I got it towed back to the mechanic and he said there was something loose on the fuel pump. A week later, it broke down in the middle of a car wash. I had to get it pulled out and towed again. The mechanic replaced the fuel pump again. A week and half later, the fuel indicator kept going up and down and then said I had no more gas when I knew I had quarter of a tank so I brought it home and filled it up at a local gas station. It ran well after the fill up. Didn't drive it for a week because I went on vacation. The day after I came back I went to the grocery store and it drove fine, but after it sat in the parking lot for 15 minutes, it wouldn't start. I let it sit for 6 hours and came back later that night to try again. It took 4 tries for the car to start and was able to drive it home, paranoid thinking that it was going to break down again. It has been sitting in my driveway for the past 2 weeks.