The Signs of a Bad Fuel Pump on a 1991 Civic Si

The 1991 Civic came in three body styles -- hatchback, sedan and liftback -- and the Si model come as either a hatchback or a liftback. The Si was the high-performance trim level of the 1991 Civic and came equipped with a 108-horsepower, 1.6-liter four-cylinder engine. A fuel pump transported the fuel from the fuel tank to the fuel rail on the engine. When the fuel pump starts failing on your 1991 Civic Si, there are four telltale symptoms.

Fuel Pump Function

The 1991 Civic Si's fuel pump is an electric pump mounted in the fuel tank. This pump turns on when you turn the vehicle's ignition to the "Run" position. When operating correctly, the 1991 Civic Si's fuel pump creates the 36 to 36 psi of pressure in the fuel lines needed to keep the vehicle running correctly.

Stalling at Idle

Stalling at idle is a telltale sign of a failed fuel pump in your 1991 Civic Si. You can keep the Civic running by holding the accelerator pedal slightly depressed. This means that the fuel pump is not creating the necessary 36 to 37 psi in the fuel system, resulting in the stalling of the engine. This can sometimes be an intermittent symptom -- meaning one day the engine operates fine and the next it stalls at every stop.

Rough Running

As the engine speed increases, the 1991 Civic Si's engine requires more fuel to accelerate correctly if the fuel pump is not creating the prescribed 36 to 37 psi of fuel pressure. In this instance, you may experience sharp drops of power and even back-and-forth jerking of the entire car as the engine receives fuel and then starves for fuel.

Hard Starting

There are two types of hard starting that indicate a failed fuel pump. The most common is when it starts hard nearly every time. This is indicative of a fuel pump that is not creating the 36 to 37 psi of fuel pressure needed by the 1991 Civic Si.

The second, less common, symptom is overnight hard start. This is when the car starts fine throughout the day, but starts hard when the vehicle has sat overnight or for extended periods of time during the day. This symptom is indicative of fuel pump bleed-back. The fuel pump may be producing plenty of pressure to run the Civic, but it is not retaining the pressure in the lines once it's shut down.

No Starting

The final stage of fuel pump failure on the 1991 Civic Si is total failure. This is when the fuel pump does not create even enough pressure to start the vehicle -- typically less than 15 psi. When this condition occurs, the Civic's engine will crank over, but will not start.