How can you tell if an injection pump is bad? In a previous blog, we talked briefly about some of the common problems that can arise with your Bobcat’s fuel injection pump for the Doosan Engine, and how to test it. The fuel injection pump plays an important role in your vehicle's performance and can directly alter your vehicle’s engine and fuel system. Whether you’re having issues with another part of your fuel system or you’re dealing with an issue related to your Bobcat fuel pump, it’s helpful to understand the role this part plays alongside your engine and the entire fuel system.
We’ll go over the basics of what makes up the 2.4L high-pressure fuel injection pump also known as the “7249380” fuel pump for the Doosan D24 and D18 Engine which fits some of the most well-known Bobcat and Kubota vehicles including excavators, skid steers loaders, track loaders and Toolcats. (You can cross reference this part with your model type here.)
We’ll also go over the basics around a 3.4L high-pressure fuel injection pump also known as the “7256789” fuel pump for the Bobcat Doosan D34 Engine which is used in some of the larger Bobcat track loaders, steer loaders and versa handlers. (You can cross reference this part with your model type here.)
Aside from the D34 pump being larger and not having an internal pressure relief valve, both pumps are almost identical in the way they operate. The D34 pump has an internal pressure relief valve in the fuel rail compared to the D24 pump which has an internal pressure relief valve directly in the pump. The purpose of a relief valve is to regulate fuel pressure in the fuel rail so if it exceeds the preset PSI, it releases any excess pressure that is created inside of the pump (for the D24) or the common rail (for the D34).
Both pumps have a fuel lift pump which is a low-pressure fuel supply pump that transfers fuel from the tank through the fuel filter and into the injection pump (also known as the cavity pump). The lift pump charges and pressurizes the injection pump to 86-87 psi with the rotary vane pump which maintains pressure through a low-pressure relief valve that is auto-set to roughly 87 psi.
These Bobcat Doosan D24 and D34 fuel pumps both have an IMV valve (inlet metering valve) which electrically controls the common rail pressure by regulating how much fuel goes to the two high pressure pistons located on your fuel injection pump. The IMV has a wired screen that acts as the last line of protection before fuel moves to the fuel rail and injectors. Both pumps also have a fuel temperature sensor which is also controlled electronically and is located next to the IMV.
Now that we’ve covered some of the fuel pump basics in your Bobcat vehicle, we’ll summarize how it works in conjunction with the entire fuel rail system. The injection fuel pump applies high pressure fuel to the fuel rails, the common rail fuel system then acts as a regulator for fuel pressure, injection timing and to store fuel. The fuel then gets sent to the injectors which deliver fuel to the engine.
As we have mentioned in many of our other blogs, one of the most common ways for any of your diesel parts including your fuel injection pump to experience premature failure is due to fuel contamination from dirty diesel or gasoline.
Common signs indicating there may be a problem with the fuel injection pump:
In summary, the fuel injection pump that fits Bobcats is a vital component in your Bobcat’s fuel system and engine. The pump plays a role creating high pressure fuel which is then sent to the common rail fuel lines. If you notice signs that could point to an issue with your fuel pump or that your pump is going out, do not continue to use your vehicle even if it is still running as this could result in more issues such as air entering the fuel system. Whether you plan on maintaining your fuel injection pump yourself or taking it into a dealer, we recommend periodically inspecting your fuel pump for leaks, wear, metal shavings and water contamination every ~250 hours, along with the injectors.
For the D24 Engine
For the D34 Engine
Expert Diesel Parts is here to supply your diesel fuel parts. If you have any questions related to your fuel injection pump, email us at contact@expertdieselparts.com If you are looking to purchase a brand new fuel pump for the Doosan engine to fit your Bobcat skid steer, excavator, track loader, etc, check out our catalog of fuel pumps today!
