91R

91R is a designation that can refer to several different things, most notably a common type of fuel pump relay used in automotive applications. This relay is a critical component in many vehicles, responsible for controlling the flow of electricity to the fuel pump. When the ignition is turned on, the engine control unit (ECU) sends a signal to the 91R relay, which in turn closes a circuit, powering the fuel pump and allowing it to deliver fuel to the engine.

A malfunctioning 91R relay can lead to a variety of drivability issues. Symptoms of a faulty relay often include the engine failing to start, the engine stalling unexpectedly, or a lack of power. In some cases, the fuel pump may intermittently stop working, causing the engine to hesitate or sputter. Diagnosing a problem with a 91R relay typically involves checking for proper voltage at the relay socket and testing the relay itself for continuity and proper operation. Replacement is usually a straightforward process for mechanics.

Beyond automotive applications, the designation "91R" might also appear in other technical contexts, such as part numbers for electronic components or specific model identifiers for various manufactured goods. However, its most prevalent association remains with the fuel pump relay.