Dodge Cummins

As the area’s leader in diesel engine repair and service, at FSS Diesel we have become aware of the most common problems in popular diesel brands, such as the Dodge Cummins. Many Dodge Cummins owners have seen the effects of a bad high pressure pump in their diesel engine. Whether you have dealt with a hard start, knocks in your engine, or even your truck not starting, we can help. Give us a call today to see how FSS Diesel can repair your engine to better than factory settings.
What is the Function of the High Pressure Pump?
The high pressure pump controls your fuel rail pressure; the pressure used to start your engine. The high pressure fuel is pumped to the filter housing and injector pump. The injection pump can become damaged if your high pressure pump fails because it would then have to pull fuel from the tank. This long pull will exceed the load your injection pump was designed for. Keep in mind that it takes about 4000 PSI rail pressure to start your engine.
Symptoms of a Bad High Pressure Pump
There are several common symptoms of a bad or failing high pressure pump. Below we will discuss many of them and detail what you can do to diagnose your issue. We will also let you know when you should bring your vehicle into us, at FSS Diesel, for further diagnostic testing that only a highly trained diesel technician will be able to perform.

• No Start or Hard Start
- You can check to see if smoke is coming from your tailpipe; if not, then no fuel is getting into your cylinders
- We will:
o check for supply to your high pressure pump and monitor your rail pressure to ensure you have high enough PSI to start
o Take a look at your injector connectors tube; if it is not seated in your injector you might have a bad tube or the torque on the nut may need to be machine-adjusted
o Ensure that your fuel pressure limit valve is not leaking at idle or while cranking
o Verify that your high pressure pump volume is reaching the 4000 PSI needed to start your engine
• Black Smoke
- You can check to see if you have a dirty air filter
- Determine whether you have an exhaust leak or boost leak by listening for a high pitched squeal while driving at full load
- We will use a scan tool to cut out each of your cylinders one at a time to determine if the smoke disappears while one cylinder is out
• Misses
- We will scan and isolate your cylinders one at a time in an attempt to identify the problematic cylinder
- Bear in mind that engine misses could be a sign of several other problems, such as an excessive valve lash, low compression, and a missing or damaged chamber gasket
• Knocks
- This issue is most likely related to a cylinder, we will isolate your cylinders using a scan tool or cap off each injector, one at a time, to locate the problem
• Surge at Idle
- Typically resulting from low or no fuel supply pump pressure, we can determine if this is the issue by checking the actual pressure against your desired pressure of 4000 PSI
• White/Blue Smoke at Idle
- This is normal at certain temperatures and altitudes as long as the smoke clears in about a minute or less
- If the smoke burns your eyes, then this is indicative of un-burnt fuel
- We will check to ensure that rail pressure is 0 PSI when your engine is off
- We will also double check for other issues, such as a leaking injector nozzle tip
• Low Power
- First, you should check for a dirty air filter which can restrict air intake and cause low power
- We will take look at your throttle to see that it has full travel to your injection pump
- We will then see if your shut off solenoid pulls entirely into the run position
- Low power can also be a sign of manifold leaks, which we will also look for
- Finally, we would look at your intercooler hose connections, boost line leading to your aneroid hosing in the injection pump (AFC), and AFC diaphragm
• Stalling or Dies on Deceleration
- Take a look at your idle speed, anything outside of 800-850 rpm is not normal and you should bring it in to us
- If this usually occurs after your vehicle has sat overnight and you experience a long crank time, you probably have a cracked injector line; we can take care of that, too
• Air Intake Heater
- Some symptoms of a bad high pressure pump can actually be related to an overactive air intake heater, be aware that at colder temperatures and in certain altitudes your air intake heater will cycle more often
• Turbocharger
- A faulty or spent turbocharger may also disguise itself as part of a bad high pressure pump problem
- Check to see that you are not lacking fuel or experiencing an exhaust leak which could cause poor performance
- Bring it into us and we can check your turbo spin, inspect the compressor wheel for damage and examine the wastegate actuator to determine if you actually need a new turbocharger
• Slow to Shut Off
- This is a frequent problem we see occurring at or above 150,000 miles
- Bring your truck into FSS Diesel so we can test to see if metal particles have leaked into your overflow valve and shutoff solenoid and determine whether we need to change these and your injectors out
• Rough Run
- This can also be a result of metal particles, although these would be blocking the holes in your nozzle tip of your pump; we can correct this for you in the shop

Why Does the Dodge Cummins High Pressure Pump Fail?
As discussed, the high pressure pump serves to build high pressure and deliver it to the fuel rail manifold where the pressure is used to start your engine. In the manifold, the high pressure fuel flows through injector lines and your injector connector tubes to reach your injectors. These injectors in the manifold each have a hollow check ball that is designed to hold the high pressure fuel until fuel solenoid is actuated. When the solenoid is actuated, the hollow check ball rises off its seat and an injection takes place. Approximately 4000 PSI rail pressure is finally used to start your engine. In several instances, this system is damaged by one of the following: the injector connector tubes leak, the check ball in the injector leaks, or the high pressure limit valve leaks. In any of these cases, the rail pressure needed to start the engine cannot be achieved.
Why Has Chrysler Not Repaired this Issue?
It is obvious that pressure, even originating at the fuel supply pump, is critical to the operation of the high pressure pump and directly affects your engine start. Chrysler argues that pressure does not matter, so much as volume. It is because of this stance that there specifications for volume are not high enough to evoke a problem when in testing stages.
Your High Pressure Pump Has Failed…What are Your Options?
There are three main options for replacing your high pressure pump. We will explain the first two and then detail why we think the third option is your best.
Option 1 – If you have a 2003 or 2004 model, your original fuel supply pump is mounted on the fuel filter housing. Replacement fuel supply pumps for these model years still mount on the filter housing but, have been updated in other aspects.
Option 2 – The 2005 through 2007 5.9L options originally had the fuel supply pump mounted in the tank. These can be replaced with pumps, such as the FASS pump or BD Max-Flow pump which both mount on the frame rail, replacing the in tank supply.
Option 3 – Install a VP44 Cummins Injection Pump. This pump is an electronic rotary distributor pump. It is your best option because it can vary fueling and injection timing, minimizing the opportunity for loss of pressure. Installing the VP44 pump with a kit will save you from buying another diesel injector pump and allow for future replacements to be of the feed pump rather than the injector pump, which is much less expensive.
Call us at FSS Diesel today to set up an appointment so we can take a look at your Dodge Cummins.
FSS Diesel’s Vehicle Specializations:
- Mitsubishi
- Ford Powerstrokes
- Dodge Cummins
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- International Navistar
FSS Diesel’s Service Specialties:
- Electrical Service
- Transmission Repair
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- Scheduled Maintenance, Service and Repair
- Check Engine Light, Service & Repair
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- Wheel and Tire Mount & Balance

About Us and What We Do

2323 Quarry Street Dallas, TX, 75212 817-939-9629 Monday-Friday 9am-6pm FSS specializes in Ford, Dodge, and Chevy diesel truck services from bumper to bumper: Repairs Performance Maintenance   We install: Car audio and video Lift kits and Lowering kits Exhaust Kits Wheel …
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found FSS Diesel on line and had my 2005 ford excursion 6.0 towed there for free to have my water cooler and oil cooler replaced and kevin and his crew did an outstanding job also the price was alot better then ford and the work was great. I stay almost...

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817-939-9629
2323 Quarry Street Dallas TX, 75212
Info@FSSDiesel.com
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