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Q: Bad fuel in tank.

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Jeep has been sitting for a while and has bad fuel in it along with a dirty gas tank... Starts up shifts perfect but sometimes runs rough and stalls...

My car has 65000 miles.
My car's transmission is unknown to me.

Hi There, If the fuel in the tank is bad along with a dirty fuel tank, this is quite likely a large part of the reason for the vehicle running rough and stalling at times. When the fuel is bad, it loses it’s ability to ignite under those specific conditions designed to happen in your vehicle’s engine. Gasoline is a highly refined product brewed to a certain chemical composition with very specific characteristics. One of the most crucial components to this is the chemical makeup of fuel that defines its’ ability to combust under these specific conditions. This is what defines how easily (and under what conditions) the gas vaporizes so it can be efficiently burned in your car’s engine. However, even the most highly volatile components in gasoline also tend to evaporate over time. As they do, the fuel’s volatility degrades. The less volatile the fuel, the less effectively it burns in your engine. Hydrocarbons in the fuel react with oxygen to produce new compounds that eventually change the chemical composition of the fuel, leading to gum and varnish deposits in the fuel system. These deposits and impurities can coat surfaces, clog up fuel lines and filters, as well the small orifices in a carburetor (jets) and the even smaller orifices in a modern car’s fuel injectors. I would recommend having a professional from YourMechanic come to your location to take a look at your Jeep.

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