Mike's 1993 Dodge Cummins Truck Blog

The pump is back in. Runs better. Way more power. No gray smoke at idle. But some off idle through full throttle.

First pic is how I verified that the key was in the gear’s slot. You can see the very end of the key nearest to the shaft. The key only sticks up barely 1/16″ above the shaft. Doing this gave me far more confidence.

When I was torquing the nut on it didn’t feel so mushy going on. Here’s another hint. The threads of the pump stick out past the nut about 1.5 threads worth. The shaft was flush with the nut when the key got mushroomed.

The far left key is the new one from Cummins. The middle one is the one that got mushroomed. The right one came from the hardware store. The new one and the middle one both have a deep mark in the middle of the key. This distorts the keys slightly so they both are a tighter fit! This keep them from falling out during pump install.

As for the smoke. If I understand correctly my timing is still a bit retarded causing excess unburnt fuel. The pump now looks a bit more advanced than it originally was. This first pic is where the pump timing is set now.

This second pic was the pump timing when I received the truck.

Today I was convinced by 2 pump shops to take the pump out to find what they thought were timing issues causing the gray smoke. It then occurred to me that I could use a mirror to see in the key way slot in the gear. The slot was completely empty. I could see all of the way down it.

Here it is. A mushroomed key! I must have been close to the slot as a small part of the key was still at full height.

After filing and grinding, I took a punch and hammered the key out again.

Small diagonal cutters grab keys very well so they can be leveraged out nicely.

I also checked the throttle indexing again. It was fine. It would change the power output more than it would cause gray smoke.

Here is the mark I added to the throttle shaft to help me index it.

I also found out that I could leave the fuel line in place and still remove the pump easily.

Drop in all 4 screws. Carefully install the governor spring between the top hat on the governor and the throttle arm as seen here.

As the assembly is brought down to the pump body 2 things have to happen to make them fit together. The collar on the screw at the far left in this pic has to make it to the larger hole for it in the pump body. This is tough because the fuel screw is pushing on the governor arm that has two strong springs on it. It might help a little to back the fuel screw almost all of the way out. It will still push on the governor arm, but it will interfere less. Be careful not to let the collar scratch or gouge the surface of the body. That might cause a leak since that is the surface that the seal sits on.

Once you do get the upper assembly mated to the body, turn the screws in evenly. It’s a little easier to add the throttle arms after all of the screws and distance settings are done.

Set the correct distance that you measured and wrote down for your pump on the fuel limit screw.

Here is how the two bushings and the spring are assembled.

Slide the 2 springs and both bushings onto the throttle shaft. Here is an easier way to wind up the throttle spring while putting the throttle arm over the shaft. I just used an allen key for leverage. Worked very nicely to hold the spring out of the way while the lower throttle arm is installed and correctly indexed!!

Notice how both hooks of the springs are wrapped around the posts. The lower throttle arm is installed.

Here you can see the mark I made on the throttle shaft that lines up with the single index mark on the lower throttle arm. Click on this pic for clarity.

In my hand is the nut and the upper throttle arm. Over the throttle shaft I placed the lock washer and the large rust colored thrust washer. Then the upper throttle arm is added followed by the nut. Tighten the nut, but not too hard. It’s only a 6mm thread.

Add the TPS bracket. Carefully tighten the screws as they are threading into aluminum.