P-pump performance with The Adjuster by Attitude Performance Products
On-the-Fly Fueling Changes Made Easy for P-Pump–Equipped ’94-to-’98 Dodge Rams
Historically, increasing a 12-valve 5.9L Cummins engine’s performance with only a Bosch P7100 high-pressure injection pump (P-pump) required modifying the pump’s air-fuel control and adjusting its fuel plate.
While making the right tweaks helps increase fuel delivery to the engine, one of the drawbacks to these changes is that the new settings are semi-permanent. So, if the fuel mixture is too rich or lean for the application, there is no way to make adjustments without further tinkering with the pump. The process can be a continual guessing game, but that is where the Adjuster by Attitude Performance Products comes in handy.
The Adjuster allows the driver to manually modify the fuel-injection strategy from inside the truck. A dash-mounted control knob provides the ability to precisely tune a P-pump for optimal economy to maximum performance without having to move from the driver seat. The device is said to contribute a number of benefits, like controlling EGT, increased boost, and improved economy and power, while helping to decrease excessive exhaust smoke.
Adjustability comes by replacing the stock fuel plate and AFC arm with the Adjuster’s housing plate (with adjustable arm) and longer AFC arm, which are designed for full fuel advance. The plate’s adjustable arm operates via a cable-actuated threaded rod in the housing. A knob on the in-cab controller rotates the cable through 16 settings. By retaining the AFC housing, factory boost advance is maintained for better driveability. If a bit more power is desired, an optional control-rod plug can be installed in the pump housing to further enhance fuel tuning. The plug allows the control rod to travel an additional 3mm further than stock (21mm total), which results in a power increase.
We located a daily driven ’96 Dodge Ram 3500 with a P7100 injection pump that is a perfect candidate for the Adjuster. The 12-valve Cummins under the hood has been modified to make more power. The original fuel plate is ground down (shaved) for increased fueling, and the turbocharger wastegate is blocked off to increase boost. A noticeable, negative side effect seen from the DIY fuel-plate modification is that the engine generates black smoke on acceleration.
With the Adjuster in tow, we made our way to Solvang, California, where Jay Storey at Storey Motors helped with the installation. Read on through the photos and captions that highlight the process.
Our Adjuster installation was smooth and straightforward, and the helpful people at Attitude Performance Products eagerly fielded any questions that arose about the installation process or using the device to make adjustments.
When driving our ’06 Dodge Ram 3500 truck with the Adjuster installed, there is definitely a noticeable difference in the 5.9L Cummins engine’s performance. The first improvement is a slight seat-of-the-pants power increase when the controller’s knob is cranked all the way to the 16th position for max fueling. Even more noticeable is the lack of smoke when the accelerator pedal is matted (even at that 16th position). Using AutoMeter Competition Instruments pyrometer and boost gauges, the already-bumped-up 30 psi of boost did not increase during our test. However, the turbocharger did reach peak boost quicker, which improved the truck’s acceleration.
After using the Adjuster for two months, Sean says, “The ability to refine fuel settings on the highway is a great asset for increasing fuel mileage. If you are going from a stock fuel plate to the Adjuster, the gains will probably seem huge.”