Upgrading The Fuel System On A Cummins Powered Work Truck
Proper operation of the fuel system in any diesel engine is of vital importance, especially with modern, high-pressure common rail engines. Getting the fuel from the tank to a Cummins common rail engine efficiently involves utilizing a low-pressure lift pump in or near the tank feeding an engine-driven, high-pressure CP3 pump to pressurize the fuel rail and feed the injectors.
Roy Dorn’s 2006 Dodge 3500 work truck has more than 207,000 miles on the odometer and seemed to have a hard time keeping up with the desired rail pressure in the hotter tunes that the crew at Beans Diesel Performance installed in the truck. When the truck was strapped to the dyno and running through the new
EFILive tunes, it made much more power than stock in all five of the tune positions, but struggled to maintain demanded rail pressure especially at higher rpm.
After driving the truck for a few thousand miles, Dorn noticed it started to feel as though it was losing power in tune 3 and sometimes in tune 2. He took it to Beans Diesel Performance where the team, knowing that the original factory fuel system had more than 200,000 miles on it, decided it was a good time to upgrade both the lift pump and high pressure CP3. It was recommended that the new AirDog II-4G fuel pump and filter system to be installed with one of its own BDP fuel tank sumps and a Fleece Performance Engineering PowerFlo 750 CP3.
Installing the AirDog II-4G not only bypasses the failure-prone and typically weak in-tank factory lift pump on this model Ram with a stronger pump, it also removes entrained air from the fuel, filters the fuel and removes water. The fourth generation (4G) design uses a self-aligning, low amperage motor that is more efficient and lasts longer than previous designs. It also features an intermediate pump shaft that separates the pump motor from the fuel in the dual-feed gerotor pump. Rather than sucking fuel from the tank using a draw straw or using the internal pick-up, the team at Beans suggests using its fuel tank sump installed in the bottom of the tank to gravity feed the AirDog pump. Since the AirDog uses an easy-to-access fuel filter and water separator, we also opted to use a Fleece Performance Cummins fuel filter delete block to eliminate the factory filter, which is hard to reach for service and no longer necessary.
Fleece Performance CP3
The Fleece Performance Engineering PowerFlo 750 CP3 is a new Bosch CP3 that the team at Fleece modifies with a 10mm stroke cam (up from 8.5mm stroke in a stock CP3) to enhance flow capability. The PowerFlo 750 also eliminates the 3,000 rpm fuel flow restriction that is inherent in the factory CP3 design, allowing it to deliver more fuel at higher rpm where you need it most.
As the name implies, it is capable of keeping up with the fuel demands of a 750 rear-wheel-horsepower engine with the proper complementing upgrades (they have measured as much as 822hp to the wheels in a single PowerFlo 750 installation). They are each individually tested in-house to make sure they are ready to deliver right out of the box. Since the PowerFlo 750 is a completely new unit, there is no need for a core charge, allowing owners to sell their old CP3 to help offset the cost of the new unit.
After we brought the truck and our shiny new parts up to the Beans Diesel Performance shop in Woodbury Tenn., Jack Grubb went to work on the big truck. To diagnose the poor running Dorn had been experiencing over the past few days, Grubb connected a shop laptop and flashed the tuning back to the stock tuning and the truck was still feeling sluggish on the top end of the tach.
Since the trouble stayed with the truck after the EFILive tuning was reverted to stock, he knew the problem was with the truck and suspected the fuel system. Some data logging revealed that it was now having trouble maintaining rail pressure even with stock tuning showing that the truck really needed a fuel system upgrade.
Grubb completed the fuel system upgrade in about 5 1/2-hours, including the typical slowdowns related to our photography. Experienced DIYers should be able to complete the installation in a day without too much difficulty. Be sure to practice safe shop techniques especially when routing hoses and wire harnesses near hot or moving items in the truck. Follow along over the next few pages for an overview of the installation process. DW
After Grubb completed the installation, the truck was strapped down to the BDP Dynocom chassis dyno to see how the upgrades measured up. Chase Lunsford ran the truck through its paces on the dyno, checking each tune level on the CSP-5 switch. He found that the fuel system upgrades provided a more solid platform for making good, reliable power as Dorn’s work truck showed increased horsepower and torque across the board.
In the lower tunes Dorn uses on a daily basis, the truck made 30 to 40 more horsepower than it did on the old pumps, while the more aggressive upper tunes saw around 10 more horsepower. On the torque side of the dyno graph, the truck made 35 to 70 more ft-lb of torque on the lower tunes with up to 50 more on the upper tunes. We recorded peaks of 478.7hp and 902.7 ft-lb of torque—not bad for a work truck with over 200,000 miles on the clock.