Your Buick fuel injector's mission is to measure the amount and timing of fuel to your engine's cylinder. The injector depends on an electrically operated valve that lets fuel into the engine. The injector has a set of small holes at its end to spray that regulated fuel amounts into the engine. The timing (ie: how long the injection nozzle's remains open) will determine how much fuel is injected, and is controlled by a computer. In addition, a separate fuel pressure regulator controls the pressure of the fuel in the injectors. Older cars use a multi-port fuel injection system, which might also be called port, multi-point or sequential fuel injection systems. With multi-ports, there is a fuel injector for each cylinder, usually located close enough to spray directly into the intake valve. These systems provide more accurate fuel metering and quicker response. There are two main types of control for multi-port systems: One type uses fuel injectors that are opened at the same time. The other type, sequential multi-port fuel injection, uses one injector that opens just before the intake valve for its cylinder opens. The advantage of the latter: if you step on the pedal suddenly, the system responds quickly since the fuel injector only has to wait only until the next intake valve opens, instead of pausing for the next complete revolution of the engine. But whether your Buick fuel injector is a sequential multi-port system - or one of the new direct injection systems - you can find the right set here for a replacement job.