The ignition timing is incorrectly set.
The emissions system is not functioning properly.
The carburetor/fuel injection internal parts are excessively worn or even damaged.
The tire pressure is low or the tire size is incorrect.
There is fuel leakage and/or fuel order.
The fuel feed or return line is leaking.
The tank was overfilled.
The evaporative canister filter is clogged.
The fuel injector internal parts are excessively worn.
The fuel injector(s) are leaking.
The carburetor is worn.
