[bwest]

I went to refill my almost empty gas tank a few days ago and noticed the pump stopped around 10 gallons even though I knew the car could probably take 15 gallons. I kept playing with the pump handle (thinking it was a pump issue) and eventually got 13 gallons into the tank. When I turned the car on it showed that the tank was 100% full. This seemed odd but I didn't think much of it. I then drove the car about 60 miles the next few days and noticed the tank was still showing 100% full and had not moved. The remaining mileage was also stuck and not going down. I took it into my Mazda dealership today and they said they've not seen this issue before and are working with Mazda corporate to try and fix it. They said they're going to have remove the fuel pump and look at the wiring going to the pump and most likely will have to order new parts and need my car for multiple days They still don't know what the exact root-cause of the problem is.

Anyone else had this happen?

 

[ThunderTortoise]

Since you had to override the handle safety shutoff that many times, it sounds like you badly overfilled your tank and took up the air gap that's normally there for thermal expansion. Drive it another 30-60 miles and see if your fuel level starts going down again.

 

[rnjoe]

I went to refill my almost empty gas tank a few days ago and noticed the pump stopped around 10 gallons even though I knew the car could probably take 15 gallons. I kept playing with the pump handle (thinking it was a pump issue) and eventually got 13 gallons into the tank. When I turned the car on it showed that the tank was 100% full. This seemed odd but I didn't think much of it. I then drove the car about 60 miles the next few days and noticed the tank was still showing 100% full and had not moved. The remaining mileage was also stuck and not going down. I took it into my Mazda dealership today and they said they've not seen this issue before and are working with Mazda corporate to try and fix it. They said they're going to have remove the fuel pump and look at the wiring going to the pump and most likely will have to order new parts and need my car for multiple days They still don't know what the exact root-cause of the problem is.

Anyone else had this happen?

Any follow up on what’s wrong with your fuel gauge? I drove my CX50 about 70 miles and fuel gauge dropped to 3/4 full. Today, it was reading full, with no explanation. The remaining miles reading 230. I will drive it for a few days and see what happens. Back to the dealer next week.

 

[bwest]

Since you had to override the handle safety shutoff that many times, it sounds like you badly overfilled your tank and took up the air gap that's normally there for thermal expansion. Drive it another 30-60 miles and see if your fuel level starts going down again.

I really don’t think I overfilled the tank as it was almost on dead empty when I filled it and the safety shutoff clicked when the tank should have only been 2/3rds full (unless the gauge was already inaccurate and I wasn’t on empty?) Also, I was able to get another 3+ gallons in there after the initial safety click. If it was close to full at the initial click I would have overfilled it so much that would have overflowed out of the tank (which it did not). So either the gauge was reading incorrectly before I filled the tank or something else is going on. Mazda still hasn’t figured out the root-cause and has my vehicle in the shop.

 

[bwest]

My dealership called me tonight and said that they got to the fuel pump and it was overflowing with fuel as the tank was more than full capacity. They said they reset everything and drove the car for a bit and got the fuel to go down. They said that everything appears to be functioning now and to just keep an eye on things. However, this leads me to believe that the fuel gauge was not accurate when I was filling up the car and actually had more gas in the tank than it said and the gauge itself is problematic. I think this could also be related to why I was getting low MPG ratings around 17-18 MPG….even when driven with a light foot. I think the gauge was off which threw off the MPG calculation. This is just my guess and the dealer didn’t really want to get into all that conjecture as they said “it’s working normal now”.
I’ll follow up after driving it for a few weeks to see if any of these problem persist.

 

[ZeekZirconPPT]

Top off the gas tank, reset your trip meter, drive until you need gas again and compare.

For reference the CX50 has a 15.8 gallon tank. However you will almost never fill that much as approximately 2 gallons are held in reserve. 2 gallons keeps the fuel pump submerged so it doesn't pump air risking damage to your fuel system.