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How the Cummins PT fuel pump works?

September 20, 2022


Cummins is a reputable multinational brand with a strong presence on the market. They are widely known for their sturdy generators with low fuel consumption, minimal noise, high output power, and reliable performance. These qualities are among the reasons customers have made the brand a favorite.

If you’re reading this, you’re probably wondering how the Cummins fuel pump work. It’s important to note that the PT fuel system is a patented product of Cummins Engine Company, an American company that manufactures and markets a complete line of diesel and gas-powered engines. The system comprises different features, including fuel connectors, injectors, PT fuel pumps, etc.

The Cummins PT fuel system at a glance

To understand how the Cummins fuel pump works, it’s important to first consider how the PT system works, especially since the fuel pump doesn’t work in isolation. PT stands for pressure-time, a type of system introduced by the company in 1951. It replaced the proprietary ‘Double Disc’ system, sporting a new design that requires fewer moving parts than the double-disc system.

In a nutshell, what the PT fuel system does is replace the fuel injection by modifying the way fuel pumps deliver pressure and also the time it takes. The PT system requires the injectors to meter and inject the fuel into the cylinder with metering. The interval is determined and managed by the engine speed, which in turn determines the frequency at which the camshaft rotates and, in turn, the injector plunger movement.

Like other Cummins engines, the camshaft is propelled from the crankshaft gear at a slower rate compared to the engine speed – one-half, to be precise – thereby making the fuel pump rotate at the same speed as the engine.

While this operation is going on, the governor controls the fuel pressure and engine torque, among other functions like the engine’s idling speed. This helps to prevent the engine from overworking itself while operating at the high-speed range.

 Furthermore, the throttle shaft helps to control the pressure at the injectors by aligning with the fuel passages. Because the low-pressure fuel line works for all injectors, there is no difference in the quantity of fuel and pressure supplied to all cylinders.

This fuel-metering option is beneficial because the injector performs all metering and injection functions while the low-pressure fuel lines strike out the need for high-pressure lines to serve fuel to each injector from the fuel pump.

How the Cummins PT fuel pump works

The fuel pump is an integration of the governor and air-fuel controller. The air-fuel controller is also known as a combustion controller. Its primary function is to determine the amount of fuel and air mixture that should be delivered to the burner at a rate that satisfies the firing rate.

The air-fuel controller (AFC) is an integral part of the fuel pump as it is designed to control the supply of fuel based on air intake manifold pressure – anytime the engine accelerates, is under load, and during lug-down conditions. This helps to minimize the release of black smoke.

Moving on to the details of the pump body, it comes with a bypass button on its inside to gauge the highest amount of fuel supply pressure before it opens and bypasses fuel back to the inlet side of the pump. Because the bypass buttons exist in different sizes, it is possible to adjust the horsepower setting of the engine when necessary.

The PT fuel pump has this unique construction because of the functions it was designed to perform, including:


      To draw and pass on fuel from the diesel tank and filter

To ensure adequate fuel pressure from the fuel rail to all injectors

To limit the speed of engine idling

To restrict the fastest no-load and full-load speed of the engine

To allow the user to manipulate the throttle position, thereby determining the engine’s power output

To ensure a smooth shutdown of the engine when the operator desires


Advantages of the Cummins generator set PT fuel system

The PT fuel system has a variety of advantages over conventional fuel systems. The following are some of its attractions.

1. Unlike the piston fuel system, only the oil quantity adjustments are carried out in the PT fuel pump. What this means is that the design of the PT pump eliminates the need to adjust the injection timing when installing them.

2. The PT fuel pump was constructed to work at low pressure while the high-pressure fuel line is eliminated. This allows for higher injection pressures in the PT fuel system, thus leading to better spray quality and faster speeds.

3. Compared to conventional plunger fuel systems, the fuel is injected from the PT projector, and then a large quantity of it is redistributed by the PT injector. The float tank benefits from this circulation in the form of the heat in the injector. In the event that the temperature is low in the tank, the heat is used to heat the fuel.

4. The PT fuel supply system boasts a straightforward, compact piping arrangement. There’s only one precision coupler in the entire system, while the conventional system has more.



Cummins fuel pump is a critical part of the PT fuel system and are necessary for the proper functioning of your generators. If you have any inquiries about fuel PT Pumps, you should speak with us at Junvoch. Our experts are ready to attend to you so you can have peace of mind when using your generators.