It’s been more than a decade since high-pressure common-rail technology revolutionized the diesel industry. With its first application appearing on the ’01 LB7 Duramax engine, it should come as no surprise that the heart of these systems—the high-pressure pump—hits a point where it’s time for either a rebuild or replacement. The Bosch CP3, used on the ’01-to-’10 Duramax and ’03-to-current Cummins engines, is known to last 250,000 miles or more before needing to be replaced. Of course, performance enthusiasts also know these pumps are only capable of supporting approximately 500 hp.
When it came time to rebuild the CP3 on our ’02 Chevrolet Silverado 2500HD, we headed over to the experts at Industrial Injection. Founded in 1985, Industrial Injection has been in the business of repairing and rebuilding diesel fuel injection systems for more than 30 years. Its technicians are Bosch-trained, certified, and armed with all the latest tools and equipment Bosch offers. When it comes to the CP3, it would be hard to find a group of people who know the pump better.
| After nearly a quarter of a million miles, the fuel system on our ’02 LB7 Duramax was in dire need of repair. The high-pressure Bosch CP3 injection pump is known for lasting even longer on factory engines, but shoddy modifications combined with neglect left ours in a bad way.
Since our truck had nearly 250,000 miles on the clock and had been sitting idle for two years, we wanted to see just what was going on inside before proceeding. What we found was a frozen pump with enough rust for one to think it had ingested salt water. Knowing our factory pump wasn’t usable, the folks at Industrial set to building us one of their newest CP3 pumps, an in-house rebuilt unit that utilizes the same diamond-like carbon coatings as their ultra-high-end pumps. This new pump is positioned right between the company’s standard in-house rebuilds and a Bosch remanufactured unit, making it a great value for people looking for outstanding performance at a lower price point—without sacrificing longevity.
| Knowing our pump was in need of a rebuild at the very least, we packed it up and headed to Industrial Injection’s headquarters in Salt Lake City, Utah. Anthony Park began the dissection by removing the gear drive with a three-jaw puller.
| A small screwdriver or pick is used to remove years of oil buildup out of screw orifices in the housing. If you have the time, a good soaking before disassembly is advisable.
| Next, removing the Torx-head retaining screws loosens the flange. An impact driver makes short work of the task.
| Low-pressure fuel flows through the flange, which also houses the overflow valve, low-pressure inlet, and metering unit. Removing this part of the CP3 gives access to the pump shaft and inner workings.
| With the flange removed, the shaft can be pulled for inspection. Anthony noted the wear was pretty normal for a pump of this age.
| The most troubling revelation came when the buckets were removed. Rust and corrosion had rendered the pump inoperable. Had we chosen to use the pump as-is, Industrial Injection figured the truck might have fired up but would have been low on power.
| The cancer had spread to not only the buckets, but to the plungers, springs, and housing as well. It was official—our 250,000-mile CP3 was dead on arrival.
| Industrial Injection Duramax CP3 Rebuild
| Fortunately for us, the wizards at Industrial Injection had just released a new version of their rebuilt CP3 injection pump, and we were among the first to see one go together. The new pump starts life as a genuine factory Bosch core housing that is thoroughly cleaned and inspected.
| CP3 injection pumps are relatively simple beings, with few parts. Industrial replaces all the internal parts with brand-new factory OEM units.
| The magic of Industrial’s new rebuilt pump—and what makes it different than your run-of-the-mill Bosch rebuild—lies in the custom diamond-like carbon (DLC) coating that is applied to the plungers and buckets. This coating provides low friction, high hardness, and great corrosion resistance.
| Reassembly begins with the installation of the pump’s high-pressure check valves. These are snugged by hand then torqued into place.
| Before moving on with the build, the pump housing is pressure-tested to ensure a leak-free seal from the high-pressure valves. This is very important, as even the smallest leak can have disastrous consequences.
| After passing the leak test, the pump’s new low-pressure gear pump is installed. This suction pump is responsible for getting fuel from the truck’s tank to the CP3. They lead an especially hard life on Duramax engines, where no factory lift pump is present.
| Next, the pump is flipped over and new suction valves are installed.
| With the suction valves in, Anthony turns his attention to installing the new bucket, spring, and plunger. First the plunger goes in, followed by the spring, and finally the bucket.
| A trio of special tools, designed and built by Bosch just for this purpose, holds the bucket and plunger arrangement in the housing while the shaft is installed.
| Finally, new Bosch O-rings are installed before the front flange and gear drive are fitted.
| Industrial Injection Duramax CP3 Rebuild Bosch O Rings
| Before leaving the facility, all the injection pumps Industrial builds are run on its in-house pump dynamometer. This machine is able to run pumps from idle up to and beyond their maximum revolutions per minute. It’s able to quickly determine if the proper pressure is being produced and what the flow rate is for factory and custom pumps, as well as establish if there are any internal or external leaks that need addressing prior to sending the pump out to the customer.
| Industrial Injection Duramax CP3 Rebuild Dynamometer
| Industrial Injection Duramax CP3 Rebuild Dynamometer 2
| Industrial Injection Duramax CP3 Rebuild Dynamometer 3
| What Industrial built for us is a new high-end pump for the lower-budget builder. It combines premium parts at a price point (about $1,000) that falls directly between Industrial’s standard rebuilds (about $800) and the factory Bosch remanufactured units (about $1,370). Our 42-percent-over SHO unit will easily provide enough fuel for more than 600 hp, last another lifetime thanks to the DLC coating, and cost almost $700 less than a comparable brand-new CP3. That’s a win-win in our books.
When we picked up our ’02 Chevrolet Silverado for this build, it was advertised as having new injectors, which is a common theme with LB7-equipped trucks for sale across the nation. However, as we came to find out, the injectors in our specimen were likely original and none of them were in good working order.
Since we were headed to Industrial anyway, we asked if we could bring the injectors along for a quick inspection. The results were shocking, but not surprising. While all were bad, we did find they had a set of 20-percent-over nozzles installed, which were new. What likely happened was a nozzle swap being advertised as “rebuilt” injectors.
So buyers beware: Unless the seller can produce receipts for new Bosch injectors, it’s fair to assume the used truck you’re buying is going to need them replaced.
| The first analysis performed was a resistance test on the solenoids. All eight failed, meaning while they might still fire, running would be erratic.
| Knowing the injectors were in need of replacement, we went ahead and disassembled them, just to see exactly what we were working with. Special tools and knowledge are needed to accomplish this, so don’t go trying it at home.
| Inside the injectors we found not only contaminated fuel, but also large chunks of physical debris.
| Lastly, we loaded each injector into Industrial’s Bosch test bench and ran it through a full test cycle. All eight failed, with several leaking so badly from different points that they couldn’t finish the test.
II 42% SHO Reman LB7 Duramax CP3 Pump with Upgraded DLC Coated Plungers
Part Number: 0986437303DLC-SHO