Diesel Fuel Pump Technology - Engine Builder Magazine

Diesel Fuel Pump Technology

Companies in the diesel fuel pump space are looking to keep pushing the envelope by focusing on increasing flow and pressure capabilities, durability, and functionality.

It’s no secret that diesel engines are making more power and more torque than ever before. In order to keep up with those performance gains, the appropriate amount of fuel has to be present as well. Fortunately, the aftermarket has come to the rescue.

Companies in the diesel fuel pump space are looking to keep pushing the envelope themselves by focusing on increasing flow and pressure capabilities, durability, and functionality. Here’s what manufacturers of diesel fuel pumps had to say about the latest pump technology.

OEM vs. Aftermarket

In recent years, there has been much conversation surrounding OEM pumps. Now, more than ever, people have been turning to aftermarket fuel pump manufacturers for answers and a better solution to their needs. And, just as always, those companies have been ready to answer the call.

diesel fuel pump

“Every new generation of diesel engine has come alongside advancement in fuel systems,” says Luke Langellier of S&S Diesel Motorsport. “In my opinion, the fuel system is the most critical component in the engine. What makes a modern, well-refined, extremely powerful diesel engine like we have today is a very capable and well-controlled fuel system. Every generation has pushed the limits on fuel injection pressure and each new generation of engine typically comes with more challenging requirements for emissions output, horsepower levels and noise. Those three things typically never go together, but with modern fuel systems it can.”   

Some of the primary changes and advancements made by the aftermarket have been with increased pressure capability as well as the ability to deliver extremely controllable quantities of fuel in multiple injection events.

“We’ve been focused on further increasing flow and pressure capabilities,” says Jordan Harkema of Exergy Performance. “On top of that, we have been working on further development of our CP4.2 products, as well as exploring the performance potential of the Denso HP4 found in the 2017+ L5P Duramax.”

According to Exergy, at the OE level, there has been a push to make the components physically smaller and withstand higher injection pressures while maintaining or reducing manufacturing costs.

“We’re looking to achieve higher flow, and common wear parts are modified or replaced with custom-made parts to increase durability,” Harkema says. “All Exergy pumps with a flow higher than stock are designed and developed to be at least as reliable as the stock pump it is replacing. Flow characteristics, reliability and customer service separate the various pumps available in the aftermarket.”

Another manufacturer in the diesel fuel systems space is FASS. In the last year, FASS has been busy releasing four unique drop-in series systems, which aim to provide the best filtration possible in an affordable, bolt-in package. 

“These systems utilize the factory in-tank pump for flow, while providing the water, air, and debris filtration FASS is known for,” says Jake Hopkins of FASS. “While quality and reliability have always been a focal point, ease of installation is only becoming more crucial. As diesel owners look to maximize their dollar, offering fuel system solutions that can be easily installed – either professionally or DIY – is critical.  

“With regard to OEM, all FASS fuel systems will provide superior filtration, period. More specifically, our Titanium Signature and Industrial Series fuel systems flow far more fuel than OEM setups, making them particularly well-suited to modified applications, or vehicles where the OEM pump is no longer effective.”

S&S diesel fuel pump

Out in Indiana at S&S Diesel Motorsport, Langellier says the company has been focused lately on high-pressure fuel pumps, but also catering to customers who need a better solution to OEM systems.   

“While we’ve continued to focus on optimizing our ultra-high-performance stroker pumps to support our high-horsepower racing customers, a significant amount of our resources the past few years has also gone into developing reliability solutions for common issues in the field,” Langellier says. “Many customers depend on their trucks every day for their livelihood, and we can use our experience to help solve well-known issues in the OE offerings. A high-pressure fuel pump conversion for the 2011 to current 6.7L Powerstroke has been our most recent product release.”

Across the board, these three companies agree that the goal is a more robust product that can outlast the truck itself, and one that improves upon OEM shortfalls. 

Performance vs. Daily Driver

The gap between daily driver vehicles and those built for racing and performance applications continues to get wider and wider. Therefore, you’d think the fuel system on a “regular” truck compared to that of a drag truck or a truck pull application will differ quite a bit. According to Exergy, the few similarities are that the pump will bolt-in, have similar electrical connections, and have similar high pressure and return connections. 

The differences for performance include: higher flow inlet valves, pump supply connections, peak injection pressure is typically tuned higher, on high-horsepower/race-only applications the rail pressure control valves are modified for additional flow, and internal pump operating pressures are higher to optimize filling the pumping chambers at high rpm.

“There is some cross over between the racing side and the daily driver side due to the fact that reliability is so critical to both,” Langellier of S&S points out. “While the racing market has to handle extreme abuse with pressures up to 40,000 psi and high rpm operation, it doesn’t accumulate high mileage. Some of the same specialty coatings, design techniques and experience that helps racing pumps live through the abuse for limited usage can help make daily driver pumps live for hundreds of thousands of miles. It’s all about the duty cycle and application.   

“Design aspects that benefit durability are used in both racing and street use. However, key differences in a race pump versus a daily driver pump are how controllable it is. Pumps that we develop for the street market are made to be ‘drop-in’ replacements for the factory pump, so they have special modifications to be ‘no tuning required’ so the truck doesn’t know if it has the unreliable OE pump or our upgraded pump.  

Exergy fuel pumps

“On the race pumps, since we know they are going in purpose-built competition vehicles and often controlled by more advanced ECUs with custom tuning, we trade off some ease of use for ultimate high performance.”

Due to those increased demands that performance places on the fuel system, you’d expect the use of two or three fuel pumps to be necessary. But, what necessitates the amount of pumps used, and when does it make sense to simply use a larger fuel pump versus adding additional fuel pumps?

“In our opinion, it always makes more sense to stay with the least amount of pumps required to meet the power requirements,” Harkema says. “Rail pressure control is easier, there is less plumbing and weight, and more space is available for other things. If additional pumps are belt driven, the belt typically proves unreliable.

“Using our 14mm Race pump, plus the right combination of other parts, we have had a number of people make 1,500-1,600 hp on fuel only. Our new Alpha pumps will push these numbers even higher. A 14mm race pump with nitrous can break the 2,000-hp mark. If more power than one pump can support is required, then we recommend installing an additional pump (preferably gear driven via a custom front cover).”

While Exergy doesn’t rule out the need for more than one pump, FASS says today’s pumps make it so one is all you need.

“With the release of our Competition Series systems, the need for multiple fuel pumps is all but eliminated,” Hopkins states. “While the fuel demands of extremely high-horsepower engines might’ve required multiple pumps several years ago, that’s almost always unnecessary at this point. Flowing a whopping 540 gallons-per-hour, our ‘biggest’ fuel system can support 3,000-plus horsepower with ease.”

S&S has also seen the need for multiple fuel pumps decline drastically, but says two could still be used in certain applications, while three pumps has all but gone away.

“We have progressed our high-output pump technology significantly the last few years to the point where even though power levels have increased dramatically, we’ve been able to take many competition customers from three high-pressure pumps down to only two,” Langellier says. “The amount of fuel flow and pumps required is determined by the power goals of the vehicle and the combustion efficiency. Even on race cars or pulling trucks, it still comes down to fuel economy. The more efficient the engine is, the less fuel it needs to produce more horsepower.    

“This is mostly determined by the amount of oxygen available. Sled pulling engines for example are often air limited with turbocharger inducer size limits and no nitrous oxide allowed. Those applications need more pump than normal to make the same power, because they are very fuel inefficient due to limited air. But a drag car with no turbo rules and unlimited nitrous may make over 3,000 hp on the same two pumps that only make 1,500 hp on a pulling truck. Also, drag cars are very weight sensitive, so they only want as many pumps as are absolutely required. Sled pullers don’t care that much about weight, so they lean towards having extra pump capacity for future growth potential or to handle unexpected leakage in the system.”

Not only are there similarities and differences among the pumps used for everyday trucks versus those used for performance, but the pumps used at the OE level differ as well.

FASS fuel system

“The Duramax and Cummins both use the Bosch CP3, however, between the two applications, the bolt patterns, rail pressure controls, and the locations of the supply, return and high-pressure fittings are different,” Exergy’s Harkema says. “The differences are driven by an inline versus V engine configuration as well as engine manufacturer preferences. The 2011 to current 6.7L Powerstroke and LML Duramax use a Bosch CP4.2 pump that is smaller, weighs less and has a higher pressure rating than the Bosch CP3. In 2017, Duramax changed to a Denso HP4 pump. Its layout and function is similar to a Bosch CP3.” 

To help truck owners of all light-duty diesel platforms, S&S has been working to alleviate issues with newer CP4 pumps, and it has also released a new DCR high-pressure pump for the 6.7L Powerstroke.

“For LML Duramax and 2019-2020 Cummins engines, we have a CP4 to CP3 conversion for reliability improvements,” Langellier says. “We use the same base pump, but with much different modifications to be fit for drop-in street use. On a 6.7L Powerstroke, a CP3 pump will not fit due to clearance issues with the engine block. In that case, we worked with Stanadyne/Pure Power to take what is called a DCR high-pressure pump and adapt it into the Ford 6.7L engine architecture – it has been extremely successful and popular.”

Selecting the Proper Fuel Pump

While the various OEs and engine platforms utilize different pumps, how do you know what pump might be best suited for you? We asked the experts for their advice in fuel pump/system selection.

“We always recommend purchasing the size (gallon per hour or GPH) fuel system that your truck actually needs,” Hopkins says. “There is no advantage to purchasing a higher-flow (more GPH) fuel system than what is needed. If anything, a higher flow system will produce more noise. 

S&S diesel fuel pump

“That said, it is perfectly ok to buy a larger fuel system (higher GPH) than you currently need if you have performance modifications planned. Any unused fuel will simply be cleaned and returned to the tank. Our website makes it easy to find the correct fuel system for a given engine and horsepower level. If someone isn’t sure what they need, we always recommend messaging, calling, or emailing us beforehand.”

Much like anything in life, the principal of “you get what you pay for” applies to fuel systems and pumps as well.

“Don’t always buy what is cheapest,” Langellier says. “Some companies start a ‘race to the bottom’ to see who can undercut the most. That mentality focuses on the wrong things and doesn’t focus on producing the best product for the customer. We focus on developing superior solutions and supporting them well after the sale. Buy from reputable dealers and from reputable companies.”

A good rule of thumb for pump selection is selecting a system with enough flow to meet your desired power target. All manufacturers advertise the power potential of their various designs, but if questions still exist, contact a dealer, a shop, or the manufacturer for further help.

Once you have a new pump for your engine, be sure it fits properly and gets installed correctly, otherwise, it won’t matter how good that pump is if it’s not on the engine right or set up for proper use.

“All Exergy pumps can be bolted in and run without any other changes or modifications with exception of the 14mm Race and Alpha pumps,” Harkema says. “These will require modifications to the rail pressure control tables to provide stable rail pressure control at all conditions. These pumps will also require relocating the fuel supply line to the gear pump cover on the high-pressure pump.”

Naturally, most manufacturers strive to develop fuel system conversion kits to be as seamless as possible. 

“OE type fitment, but with better than OE reliability is what I like to say,” Langellier says of S&S pumps. “Our engineers work to develop very thorough installation instructions included with the products. Reading and following instructions carefully is very important. And, with any fuel system work, cleanliness is extremely critical. These systems are so precise that even very fine debris can cause major damage.”

Pump Failures

While fuel pump technology has come a long way in recent years on both the OE and aftermarket sides of the coin, the nature of making horsepower and torque means things will break and things will fail – fuel pumps included. But, what are some of the more common reasons for failures?

“The main ‘cause of death’ we have observed comes down to poor fuel quality,” Harkema says. “Fuel with low lubricity, debris, or water, which will cause internal corrosion, are the typical causes of pump failure. It is highly recommended to use an all-in-one fuel additive that addresses lubricity, water in fuel and fuel stability with every tank. We have seen trucks that consistently used a quality additive with several hundred thousand miles on the original fuel system and still going strong. Consistent use of an additive with a proven track record for lubricity is especially important on trucks with a Bosch CP4.2 as it has a roller follower design that is more sensitive to poor fuel quality than other pumps commonly in use today.”

diesel fuel pump

Of course, due to many diesel trucks remaining in use for many, many years and subsequently many, many miles, normal wear and tear can be a source of failure.

“Most OEM fuel pump failures are simply the result of age and/or mileage,” Hopkins says. “There is little you can do to prolong the life of the actual pump, but consistently installing fresh fuel filters is always a good idea.”

Fuel contamination and poor filtration are two of the most common killers of fuel systems. Water, gas or DEF accidentally put in diesel fuel tanks is very common as well.  

“This will almost certainly kill a CP4-based pump,” Langellier says. “When that CP4 pump fails, it produces fine metal debris that destroys the injectors and the rest of the system. Converting to a CP3 (LML and Ram) or a DCR (Ford) gets you a pump that is a much less sensitive design. Even if a CP3 or DCR fails, they don’t produce the type of debris that a CP4 does, and the fluid flow path is different so it doesn’t contaminate everything downstream. Proper filtration is key. Check water separators regularly and use quality filters.”

Fuel Pump Future

The diesel industry has achieved great heights lately, so where do fuel pump manufacturers see this component and technology going next? For one, the amount of fuel flow and pressure capabilities will continue to increase. They also anticipate a bigger emphasis on filtration and ease of installation and maintenance. Customer demand will continue for higher horsepower, yet quiet, efficient and low-emissions engines, so advancements in fuel systems will continue. EB

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