Vehicle hesitation is normally caused by a disruption of fuel flow into a vehicle's engine. Adequate fuel flow into a vehicle's engine is necessary for optimum vehicle performance. Any mechanical problem or defect that disrupts normal fuel flow into an engine is likely to cause a variety of engine symptoms, including engine hesitation. What follows is a list of the most common causes of engine hesitation during acceleration.
Bad Spark Plugs
Spark plugs are responsible for igniting a vehicle's air/fuel mixture, a process that creates engine power. Bad spark plugs can negatively impact ignition of a vehicle's air/fuel mixture, which can cause engine hesitation, missing and knocking, either during acceleration or under constant speed.
Bad Spark Plug Wires
Bad spark plug wires can negatively impact the flow of current (electricity) to the engine's spark plugs, which can result in incomplete spark plug firing and engine combustion, which can both lead to engine hesitation during acceleration.
Dirty Fuel Injectors
Dirty fuel injectors impede the flow of fuel into a vehicle's engine cylinders, and this can cause restricted and/or incomplete engine combustion, which can lead to both engine hesitation and the engine missing during acceleration or at cruising speeds.
On vehicles equipped with carburettors, engine hesitation can be directly caused by a bad or abnormally functioning carburettor. A carburettor is responsible for injecting both air and gas into a vehicle's engine cylinders, and if a carburettor restricts the flow of either one, engine hesitation can occur, either during acceleration or at cruising speeds.
Dirty Fuel Filter
Fuel entering a vehicle's engine has to first pass through the fuel filter. A dirty, obstructed fuel filter can restrict fuel flow into a vehicle's engine, a condition that can cause engine hesitation during acceleration.