I drive a 2015 mazda 3 with only 85k miles. I treat it incredibly well and follow the maintenance interval in the manual religiously. The only thing Im bad about is I would literally run the gas tank to 0 miles range every single time because I would still only be putting 10-11 gallons in to the 13.2 gallon tank to fill it up so I knew it wasn’t truly empty.
Well a few weeks ago my high pressure fuel pump failed. Ended up having it replaced by mazda because I wanted the oem part. $750 part + $750 labor, ouch. Did I cause this by running my tank so low every time or is it just a coincidence? These vehicles are known to be rather reliable so to have a repair like this at 85k sucks. I now fill up at a quarter tank but I am still curious if this is my fault or if I just got unlucky.
unfortunately yes. vehicles with direct injection use a low pressure pump in the tank and of course the high pressure pump near the fuel injectors. when you run the tank low, the low pressure pump has to work harder to supply consistent fuel pressure to the high pressure pump, meaning it is working harder as well. however because the high pressure pumps run at over 1000 psi, straining them due to low fuel pressure is fatal much more often than a low pressure pump. it’s also more fatal for high pressure pumps as they somewhat rely on the fuel to lubricate the pump, much more so in diesel vehicles. so just make sure not to run it too low too often and all will be well