As we all know, a properly functioning fuel pump is vital to the health of your diesel engine overall. But, like any other component in your engine, you might have a failure. So, how do you know when it’s your fuel pump that’s giving you trouble? What symptoms should you look out for?
Today, we’re taking you through the different types of fuel pumps and what issues you might have if you’re experiencing a failure. Read on to learn more!
Failures in a Rotary Pump
A rotary pump describes a pump where the output lines are positioned in a circle. It has a distributor on, which is turned by the drive shaft. There are different versions of rotary pumps, some electronic and some not.
So what should you keep an eye out for? The following symptoms could indicate a failing rotary pump:
Hard start or hot head
No throttle control or elevated RPM ring (This is more for a Stanadyne or Roosa Master, covering a certain style through those companies.)
Seized head or plugged nozzle
Fuel in the oil
Oil in the fuel
Carbon in the fuel
External fuel leaks
With a no start on an electronic pump, there could be a problem with the electronic shutoff solenoid
Throttle alarm or shutoff arm leaking
Leaking head
Leaking advance
Wear from ultra low sulfur (Since there’s no lubrication in the fuel, you get metal parts that just wear on each other constantly
Failures in an Inline Pump
As you can probably guess, all the lines in an inline pump are positioned in a straight line. Each cylinder is operated on its own, so they can fail separately. Symptoms of a failing inline pump can include:
Fuel in the oil
White smoke from a timing issue or air
Black smoke from timing problems, a lack of air, or excessive fueling
Blue smoke from unburnt fuel
Low power caused by governor issues, lack of fuel, or a bad transfer pump
No start because of a sticky rack, bad barrel plungers, or, if it’s electronic, the shutoff solenoid might not work well
No RPM control because the rack is sticking or the governor is shutting off early
Cylinder not pumping fuel caused by a delivery valve holder that got over-torqued
Wear from ultra low sulfur
Failures in a High-Pressure Common Rail Pump
A high-pressure common rail pump is similar to a HEUI pump in that it has pistons that revolve, and it has one inlet and one or two outlets. The outlets lead to a rail that supplies the pressure. Where an inline or rotary pump applies a specific amount of pressure, the common rail handles the pressure and the ECU handles the fuel distribution.
If you’re having a failure in your high-pressure common rail pump you might notice some of the following symptoms:
They might quit entirely. This might occur if you leave them sit for a long period of time. Normally, in this situation, it would be the suction side that fails. A lot of them have a supply pump built in that sucks fuel from the tank and that’s the part that can go bad
They can get wear from ultra low sulfur
The pressure regulator fails. You might notice a hiccup in the engine as the pressure bounces too much (400 or more psi where it would typically only bounce about 200 psi)
It goes into limp mode when when the engine is under load, which can be caused by a fuel restriction or weak pump
No start issue caused by an injector staying open. While it might appear so, this isn’t actually an issue caused by the pump
Failures in a HEUI Pump
A HEUI pump is actually quite similar to a high-pressure common rail pump, although it’s an oil pressure pump. Its pressure isn’t as high, though. It only goes to a few thousand pounds.
So, if you have a HEUI pump in your engine, what should you watch out for? Some symptoms of a failing HEUI pump include:
No start, which can be caused by low oil pressure from an injector sticking open, or by an oil leak beyond the pump. If it doesn’t make the necessary pounds of pressure, it won’t start
The IPVR can fail because of a loose nut. This can cause a stall. Or, the nut can slide back and forth every time the brakes are hit, and it can fail
You can get foam in the oil caused by the wrong kind of oil. If this happens, it pressurizes differently and can lead to issues
Low fuel pressure can occur if proper oil change intervals aren’t followed
High pressure oil leaks (check your oil manifolds)
They can get wear from ultra low sulfur
Like with any issue in you diesel engine, proper diagnosis is key to fixing your problem. If you believe that you’re having an issue with your pump, DFI can help!
Need help diagnosing your diesel engine problems? Our Bosch Certified Diesel Technicians can help! Give us a call at (855) 212-3022.
