If you drive a newer vehicle, you may not be familiar with accelerator pumps. New vehicles almost invariably operate on a system of fuel injection, and the accelerator pump is a component of carbureted cars. In a carbureted vehicle, the accelerator pump works to regulate the flow of fuel that is supplied to the carburetor, increasing and decreasing it as needed. As you press down on the gas pedal, the accelerator pump works to deliver more fuel, resulting in smooth acceleration. It works along with the vacuum distributor, which is a timing device.
If you drive a carbureted vehicle, you use your accelerator pump many times, every time that you drive. Eventually, if you drive long enough and frequently enough, the accelerator pump will begin to show signs of wear. Usually, it is replaced in conjunction with rebuilding the carburetor. Very rarely, the pump may fail prematurely. Given the variables involved, it is not possible to say with certainty how long your accelerator pump will last, but it could very well last you the life of your car.
Signs that your accelerator pump may need to be replaced include:
- Car does not accelerate smoothly when gas pedal is pressed hard (note: a bad accelerator pump does not affect slow acceleration, only fast acceleration)
- Engine stalls or stutters during hard acceleration
- Exhaust smoke
Poor acceleration can be dangerous if you need to pass, merge, or perform other operations where you need to be assured that your car can accelerate quickly. If you think that your accelerator pump is failing, you need to have it checked out by a professional mechanic. An experienced mechanic can diagnose your acceleration problems and, if necessary, replace the accelerator pump.