Okay, even the old-school guys have figured out that carburetors have gone the way of the dinosaur, and they've taken the mechanical fuel pump with them. Your fuel injected Mazda has an electric Mazda fuel pump doing the work. At least it should be doing the work--stumbling, hesitation, and hard starting are all signs that your Mazda fuel pump may not be up to the job of supplying your fuel system. If you run the pressure and flow tests and find the Mazda fuel pump is failing, the next step is finding out where the engineers hid your Mazda electric fuel pump. The gas tank is one good place to look for a Mazda fuel pump. Many times the engineers stick the Mazda fuel pump in the fuel tank so that the gasoline can cool the electric motor. Alongside a frame rail or rocker panel is another common Mazda fuel pump location. Find the fuel lines and you'll eventually find your Mazda fuel pump. Or get a Mazda repair manual--we have dozens--to use as a cheat sheet. Most importantly, though, replace your Mazda fuel pump with an OE Mazda fuel pump for proper performance. Some parts stores will try to sell you a generic Mazda fuel pump, but modern injection systems don't like "one size fits all" parts. Order your new Mazda fuel pump from us and you'll get the right part at a wholesale price to get your car not just running, but running right.