Check Valves

A check valve is a common component in any piping system. In essence, it’s meant to prevent backflow. Also known as a non-return valve or NRV, it works through the fluid pressure. It’s because of this pressure that the valve opens, and the reversal of the flow that will close it. The major advantage of a check valve is that it allows the fluid to flow fully without any obstructions.  Then, as the pressure decreases, the valve closes automatically.

Now, check valves in cars are usually connected to the fuel pump. However, this component was manufactured for cars before there was such thing as electronic injection. Nowadays, fuel pump check valves are normally used in retrofitting the mechanical fuel pumps in vintage or classic cars. Because a mechanical fuel pump makes use of two-port check valve, one is situated at the inlet, and the other at the outlet. From the fuel pump, the check valve ensures that the flow of fuel goes in the proper direction while maintaining a stabilized pressure to keep the engine running.

However, because of wear and tear, the check valve may need to be replaced as needed. If not, you’ll most probably start experiencing these symptoms:

When the check valve has gone bad, the vehicle will have no ignition and will not start. Usually, to build up enough pressure to get it running again will require you to turn the key right before starting, and repeating this numerous times until it starts.

When there is not enough pressure sustained, the vehicle will run badly or even stall. This is because a faulty check valve will not be able to retain the suitable amount of pressure. To check if the amount of fuel pressure is in line with your vehicle’s specifications, you may use a fuel pressure gauge when the vehicle is running. And when you find that the fuel pressure is not up to par with what is specified, then the problem may lie with the check valve.

When the vehicle starts properly but then stalls once the fuel pump turns off, then the check valve may also be at fault. A bad valve will translate to a lack of pressure wherein the fuel flows back into the pump.

Another component in an automobile that uses a pressure relief valve is the oil pump. The oil pressure relief valve is pushed down against a spring when there’s an adequate amount of pressure. Oil then goes through the pump and into the engine, and as the pressure increases, the piston on the valve is forced against the spring which then opens it. It’s because of this that the oil is able to flow back to the crankcase, therefore preventing an excess of oil pressure. A faulty pressure relief valve in the oil pump will let the oil bleed too much, thus resulting in a lack of pressure and causing potential damage to the engine.