Over the last 30 years, the Cummins Diesel platform in Dodge Ram pickup trucks has utilized a few variations of fuel injection. The basic setup of the Cummins inline-six engine has remained similar, but there are small differences that can cause some confusion. In true Diesel Army fashion, we’d like to highlight all of the injection pump systems equipped on the mighty Cummins engines. This month we will discuss the VE pump.
General Facts And Overview
The 12-valve Cummins engine was first placed in Ram pickup trucks in 1989. It was an instant success and exponentially catapulted the sales of the truck. Those first 12-valve engines were equipped with a rotary-style injection pump referred to as the VE pump. These early engines were the grandfathers of what we all see as modern-day diesel performance.
Turning up diesels to supply more fuel wasn’t a secret during this time period. Other engines, such as the 6.2-liter Chevrolet or the 6.9-liter International in Ford pickups could also be modified to gain more power. But the difference with the Cummins was that it had a factory turbo. This made bigger performance gains possible because increasing fueling capacity also increased drive pressure on the turbocharger. This allowed for more boost that resulted in more power!
People began to realize they could fine-tune the VE pumps to make them more ideal for their intended use. These VE pumps come in a couple of forms. They first appeared in the non-intercooled engines from 1989-1991. These engines were rated at 160-horsepower, but actually made closer to 200 horsepower. In the later years, from 1991.5-1993, the engines received an intercooler, and power was backed down to a true 160 horsepower for emissions reasons. This was accomplished with smaller injectors and slight pump tweaks.
With all the nuances of the engines and pumps out of the way, let’s discuss common modifications people perform to these injection systems. First, the fuel screw is probably the easiest adjustment to make, as it is an external adjustment. The screw is located on the back corner of the pump. With the removal of tamper covers, it can be turned up by rotating the screw inwards (clockwise) and retightening the jam nut.
The non-intercooled pumps should only be turned in around 1-1.5 turns in order to avoid a runaway situation, but the intercooled pumps can in most cases, be turned in all the way. Once you turn the screw in, you will likely have to re-adjust the idle linkage to bring the idle speed back down. An adjustment of the idle smoke setting will be needed, this is done by adjusting the tension on the diaphragm spring located on the top of the pump.
The next common adjustment to the VE pump is swapping the fuel pin. By doing this, most trucks net an increase of around 50-horsepower. The fuel pin is an easy modification that requires the removal of the top cover on the pump. Once the cover is removed, you simply unbolt the pin from the diaphragm and install the new pin found in your kit.
While working on the pump, many people also replace the governor spring. The spring is located under the top cover of the pump (the area directly underneath the fuel pin). The installation of the governor spring allows for full fueling to a variety of RPM ranges. A #366 spring is used for 3,200 rpm, a #374 is good for 3,800 rpm, and lastly, a #354 allows for fueling to 4,200 rpm.
More extensive modifications are required to the engine for increased fueling over 3,200 rpm. Installing a simple 3,200 rpm kit nets you a better, more snappy throttle response which makes driving around town a more enjoyable experience.
These pumps aren’t the power monsters like the P-pumps we will talk about later, but they are still capable of packing a decent punch. With the correct injector and turbo configuration, 500-horsepower can be reached with a modified stock pump. More power is possible if you get a custom 12-mm pump configuration built by a calibrator who has proper knowledge of the topic.
Timing is one of the nicest features of the VE pump. The pump’s timing will change based on RPM so a smoother power curve is delivered. This allows for a better starting truck and makes them less noisy when running. This is because a properly tuned truck will run at the correct timing throughout the RPM range.
The VE pumps are also known for getting incredibly good fuel mileage, as well as being able to start the engine within one revolution. It should be noted that loosening the pump from the timing case and rotating it towards the cylinder head will net extra timing for those people looking to maximize their total timing value for horsepower increases.
In conclusion, the VE pump has some key benefits and features that were revolutionary back in the day that are still desirable for mechanical pump fans today. They are by far the quickest starting pump variant and deliver a better torque curve and power range than their inline pump counterparts. These also get the best fuel mileage among all the pump variants.
The only real downside to them is the limited power output of roughly 500-horsepower. The Diesel Army team is still a fan of these early first-generation Cummins trucks and enjoy seeing what enthusiasts of this platform are turning out. For more tech articles covering all things diesel, make sure to stay tuned.