Skip to content

Fueling Upgrades & AFC Modifications

This is part 3 of the Project Ram Series

Not even a week after bringing this truck home, I had already started the process of upgrading it.

Immediately after installing gauges to monitor the vitals, I started modifying the P-Pump to boost the horsepower up quite a bit.

P-Pump Overview

If- you are curious to know how a P-Pump works, this was my opportunity to learn about them as well.

To start, here is a YouTube video I found, which did an excellent job of explaining a lot of the concepts.

The AFC, stands for Air, Fuel Controller. It sits above the governor, and helps to limit the amount of fuel injected, until the turbo spools up.

The Plan

I will be adjusting a few things on my pump-

  1. Governor springs

    The stock springs, in my experience started de fueling around only 2,300rpm. This was an issue when driving in a busy city, as when merging onto a busy street, you would need to shift mid-turn.

  2. AFC Live, AFC Springs, Diaphragm, Foot.

    I will be putting in a spring intended for 35 lbs of boost. From the factory, these trucks were set to product around 20lbs of boost. The stock HX35 appears to be capable of reliability producing 35lbs. More- would push outside of its efficiency, and launch the turbine into orbit. So- I will be configuring this AFC based on 35 lbs of boost.

  3. Fuel Plate. Delete

    I will be leveraging AFC live to control the fueling. The fuel plate will be eliminated as I am able to configure the max fueling in my cab using a dial on the AFC live.

  4. Timing

    Stock timing is about 13.5 degrees.

    From- what I have seen and read- around 16-18 degrees is a good place to be, which should net an additional 2mpg, and should give a bump in power (~50hp?). Pushing 21 degrees or more, I have read will cause issues when starting, especially in the cold.

    (Note- the timing is adjusted in the next post)

Parts Used

Nearly all of the AFC modifications, I ordered from Power Driven Diesel

  1. Power Driven Diesel: Turbo Tuner Boost Controller
  2. Power Driven: AFC Live
  3. Power Driven: AFC Live Max Travel Kit
    • I went with, "30-35 psi – For trucks with a stock turbo but with additional fueling upgrades"
  4. Power Driven 3K/4K Governor Springs

Getting Started

The first step- before starting anything... I pressure washed the engine bay. I didn't want to be covered in grease only 5 minutes in.

After pressure washing, this is what I was left with:

Image showing the engine bay after being pressure washed, still wet

Next- here is a Youtube video from PDD, showing the full install process of AFC Live. I would recommend watching or skimming over this.

Removing Intake Horn, and other components

For the initial disassembly, I found my impact driver to work very nicely. Most of the bolts we will be removing, will be 8mm or 10mm.

Image showing the intake horn removed along with my impact driver.

Start by taking the intake horn off. Four bolts holds it to the manifold, one bolt for the oil-dipstick. And remove the intake pipe.

Be careful to not damage the gasket! Unless- you planned on replacing it, and already have a new one.

As a note, Power Driven, does include an instructional manual. However, I did find my self frequently looking at YouTube videos while doing some of the AFC modifications. If, you lose your manual for AFC Live, you can find it online here: Power Driven Diesel: AFC Live Instruction Manual

Image showing the instruction manual from Power Driven Diesel, with two wrenches on top of it.

After- getting the intake horn removed, we can access the AFC and Fuel Shutoff.

Removing the AFC

Info

Since- I am writing this post from the future-

Go ahead and remove the fuel-shutoff solenoid bracket.

Two 8mm screws (shared with the AFC), and one 8mm screw hidden on the back (use a small 1/4 ratchet).

You will need to remove it for doing the governor spring anyways. Get it out of the way now to make these parts a little bit easier. Its one less component in the way.

Info

I strongly suggest putting your bolts into labeled baggies.

An image showing multiple bags of bolts with labels like fan should, fan, fuel shutoff/afc

If- you are only doing the AFC modifications, you might skip this. But- I did the AFC modifications, and timing cover modifications all at the same time. I ended up with quite a few baggies of screws. The labels were useful, especially since I did this project over the course of a week, in the evenings after work.

One of the AFC bolts, is a "security bolt" It has no thread. I used a hammer, and a screwdriver to lightly indent it, to work with a flathead screwdriver.

Image showing the security screw on the AFC, with a slot chiseled into it

Afterwards, I was able to snake my impact driver onto it, and extract the screw.

Image showing me removing the security screw with an impact driver snaked between the injector fuel lines

Here- is what the security screw looked like after I removed it. I'd say I did a pretty decent job.

Picture showing the security bolt removed, in my hand, with a well defined slot for a flathead screwdriver

Now, we can remove the AFC from the engine. Pick it up and plop it off.

Picture of the AFC in my hand after being removed from the injection pump

AFC Modifications

With the AFC removed, we can start the modifications. First- there is another security screw.

I mounted the AFC into my vise to handle slotting this screw.

Another security screw installed in the AFC's cover

As before.... I used a hammer and screwdriver to chisel a slot into the bolt. And zipped it off with my impact driver.

The security screw on the AFC cover, with a new slot chiseled in

Once the cover is removed, we can see the old crusty diaphragm. I will be replacing this with a new one from PDD.

AFC with cover removed, showing the old diaphragm covered in oil and gunk

At this point, I did a horrible job taking pictures.... and the next picture in my camera, is the AFC reassembled.

But..... these items were done:

  1. AFC Spring replaced.
  2. Diaphragm replaced.
  3. Star wheel turned all the way to the right.
  4. Smoke screw backed all the way out. Tightened until it touched, and screwed in another turn or two after.
  5. AFC Foot replaced with one from PDD. You can easily grind off the end of your foot and save a few bucks if you prefer.
  6. Carb cleaner was used to clean everything up, and remove gunk and debris.

Here- is the picture taken after these items were completed:

AFC has been modified, and reassembled. Visible gunk, dirt all removed.

Note from future me - Leaking AFC Fitting

I STRONGLY recommend you pressure test your AFC before reinstalling it.

For context- I discovered the AFC has never worked properly in this truck, due to a leaking fitting.

As in- I had been driving around under base fueling, with no boost-fueling. This makes a massive difference in power!!!!

Here is a video from after I pulled the AFC back off a week after these changes, trying to track down why I had no power!!!!

The air leaking heard, is all coming from the factory fitting. While- the foot might be moving, remember- there is 140psi of pressure behind the regulator, and it is connected to the AFC using a 3/8" tube. Quite a bit more volume then the supplied 1/8 and 5/32 fittings!

In other words- it leaked air too fast to more the diaphragm.

I visited the hardware store to try and find a fitting which would be a better fit, and found a brass fitting which was close. While not perfect, It was leaking less then the stock fitting.

Picture of work table with AFC sitting on left, with air fitting removed. New brass fitting in the middle. Original fitting on the right. Threads are slightly marred

The cause of this issue- you can see the threads are marred up a bit on the AFC. Even the new brass fitting, while being a much better fit, and with teflon and o-rings, still, leaks. Just- I can actually build pressure in the AFC now.

In addition, I needed a 1/8" NPT fitting for this odd combination of parts I had. I ended up drilling and tapping the hose fittings, to instead have a 1/8" FNTP fitting.

alt text

And... after tapping, I had this:

alt text

After pressure testing again, It still leaked, however, was drastically improved...

I need to go and weld in this hole, then drill/tap to the correct size... If I do this, I will only drill / tap a 1/8" NTP-27 to eliminate the need for other fittings.

If AFC Live was not constrained by the 5/32 air-lines, I would do 3/8" instead.

Fuel Plate

The next modification, was removing the fuel plate.

Picture showing the fuel plate installed in the ppump

Remove the two flat-head screws, and remove the plate. Thats it!

Be careful to not drop anything into the pump.

Governor Springs

Next up- governor springs.

First- here is a YouTube video from PDD, showing the process of installing governor springs. I'd recommend watching, and following their steps. I found the video to be more helpful then the written manual.

As previously stated- the stock springs will start heavily cutting fuel at 2,300rpm. Not all springs are created equal either.

Some have no issues running 3,000rpm on stock springs. Others, like me, it falls on its face after 2,200, which puts a large damper on going somewhere in a hurry.

If- you did not listen to future me, and remove the fuel solenoid bracket, you will need to do that now. Tip- tiny 8mm 1/4 ratchet to get the 8mm bolt on the back.

Picture showing the Pump, with AFC on top, and the fuel shutoff solenoid bracket removed.

With this out of the way, you can see the governor spring access port. If- you see safety wire, there is a good chance nobody has modified the springs. Cut the safety wire out of the way, and remove the nut for the access hole.

Image showing the access port for the governor springs, which is below the AFC

Also- hope you don't mind some of the cramped and enclosed spaces....

A random image showing a clamp light sitting above the pump, to help provide light in the tiny confined spaces

The next part is a tad tricky. You will need to rotate the engine until the spring is nearly perfectly centered in the hole.

If it is not centered, the spring will catch on the housing.

Use a magnet when removing springs, shims, washers, and parts. You don't want to drop anything inside of the pump.

Showing access port, with governor spring centered ready to come out.

I did make a lovely homemade tool to assist with turning the engine over. More ideally, have a inch and a half wrench available.

I did not. So, I welded together a piece of metal, and cut out a notch. This fits around the fan bolt, and allows me to turn the engine.

Image of a homemade tool with a big-cutout for turning the fan

And.... after removing the old stack of springs...... here they are compared to the new.

Note- the BIG, outside spring should not leave the pump. This is your idle spring, and likely is not being changed out.

Image showing old springs, and new springs.

Toss in the new spring stack, with retainer.... and then turn the engine over to get to the springs on the other side.

Rinse and repeat, and you have new governor springs.

Next Steps?

This concludes my modifications to the pump itself.

The next part is Adjusting Pump Timing & Fixing KDP