Cummins Attitude Adjustment

Giving an old, worn-out 12V Cummins a few fueling upgrades

While the 12V Cummins might be considered a dinosaur to most in the diesel business, there are still plenty of them out on the road, working job sites and hauling cattle to the auction. The 12V Cummins takes us back to a simpler time, when unhackable computers controlled our engines’ running parameters, and all it took to make power was a little more fuel and the air to support it. The 12V Cummins was an incredible platform back in it’s day, and it can still offer great driving characteristics today with the proper setup. The mechanical P7100 injection pump had endless upgrades to supply fuel to the engine to make just about whatever power levels you wanted. They’ve lost some of their popularity because of later common rail technology, but the dinosaurs aren’t dead.

DW-2001-12V-01 — The Adjuster from Attitude Performance Products (distributed through XDP Diesel) is one of the only power-on-the-fly systems available for the older 12V Cummins-powered trucks. Thanks to an in-cab control knob, owners now have full control of fuel plate travel to adjust fueling output of the P7100 injection. Having the correct fuel rate when you need it means more power, better fuel efficiency, and lower smoke output.

In the past, setting up a 12V to do just about everything was a bit of a challenge. Sure, the injection pump could be built to put out a ton of fuel. The fuel plate and delivery valves could adjust how that fuel was supplied to the engine. However, it was always an all-or-nothing setup that had to then be controlled by your right foot. Today, thanks to the folks at Attitude Performance Products, controlling your fueling output is just a couple clicks away with their new Adjuster—a fully adjustable fuel plate housing that allows complete in-cab P-pump fueling control with the turn of a knob. Much like the adjustable chips found in the latest electronically controlled trucks, The Adjuster allows the driver to make on-the-fly adjustments to the fuel plate and rack travel within the mechanical P-pump while driving. The Adjuster kit comes with everything needed to make a complete install including the fuel armature, AFC fuel arm, cable, in-cab controller, and hardware. The new fuel armature housing can be installed on the factory P-pump just as easily as swapping out the fuel plate, with the addition of running the cable into the cab and mounting the controller.

The controller has 10 settings. You can reduce the pump’s output to below 150cc of fuel (less than stock), or you can crank up to 10 to allow max flow from the pump. The new housing will install between the governor housing and AFC housing of the pump, and it usually takes less than an hour for the complete job. The Adjuster won’t require removal of the pump from the engine. To get everything installed, just get the intake horn and fuel lines out of your way.

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DW-2001-12V-02 — The 12V Cummins has long been known for making horsepower. With no electronics to deal with, you just need to increase the available fuel and air to improve horsepower. If you do extensive modifications, the P7100 injection pump is capable of some pretty serious fuel output. However, for the average owner, just a few simple bolt-on upgrades can provide clean, reliable, and usable power to a tired old work truck.

DW-2001-12V-03 — The AFC housing is where all the control happens within the injection pump. It will need to be removed to allow access to the armature arm and fuel plate that will be swapped out for some new machined pieces included in the Adjuster kit.

DW-2001-12V-04 — Before we dive into bumping up injectors, we’ll make some changes on the injection pump to squeeze a little more fuel out of the otherwise stock pump. Starting off with these delivery valve holders, they’ll be swapped out with a stainless steel machined holder from Attitude that offers a consistent .093 orifice size instead of the factory .078 tapered style.

DW-2001-12V-05 — To remove the factory holders, the injection lines running from the pump to the injector will need to be removed, and then a special spline socket will be required to remove the holder from the pump. It’s suggested that you do this one cylinder at a time so as to not mix up or lose parts.

DW-2001-12V-06 — The new stainless steel billet delivery valve holders from Attitude offer a smooth, precise .093 port for increased fuel flow and lower restriction for the fuel to enter the injector. The new holders can also relieve camshaft and roller-bearing stress and reduce wear and tear on the injection pump.

It’s also worth noting: The Adjuster can help increase boost output (3-15psi), lower EGTs (150-250 degrees), improve fuel mileage (+10-25 percent), and increase pump life because you don’t have to always run it at its max potential.

Initial chassis dyno testing showed major changes in overall engine output, with Setting 1 making just 85hp. While not ideal for driving around, this power level could help pump fuel mileage under normal cruising because of the reduction in overall fuel flow from the pump. On that same truck, Setting 4 made a crisp and clean 200hp—more manageable for a towing situation and daily driver looking for smoke-free commuting. Setting 10 on the controller increased to 392hp, which was a bit smoky with a stock turbocharger, but it showed how versatile the Adjuster can make your truck.

The Adjuster will work on any application using the Bosch P7100 injection pump including the ’94-’98 Dodge and 4-cylinder 4BT engines used in many conversion builds. The Adjuster will also work on any vehicle regardless of modifications and power potential. Just looking to improve your stock trucks usability? It’ll do that. Looking to make your 1000-hp drag truck a little easier to drive on the street? It’ll do that, too. The Adjuster from Attitude Performance Products has helped bring the 12V Cummins back from the Stone Age of diesel performance by improving its overall efficiency, drivability, and power potential. Any truck owner should be able to get on board with these kind of results.