Mike's 1993 Dodge Cummins Truck Blog

Yesterday’s 207 mile run on 8.0 gallons to get the front bumper swapped netted 25.8 mpg with the cruise control set to 65mph. Nice! And that is with the leaking fuel tank lid.

Today I went out and planned on capping the vent tube that had a rotted vinyl cap. When I went to remove the remainder of the cap, the entire fuel/electrical assembly moved! The cap was very very loose! So I found my old strap wrench and took about 6 shots at tightening the cap on the fuel tank. I drove the truck around all day, and not a drop of fuel spilled down the sides of the tank!! What a difference!!

We will see how it affects the mileage with no known fuel leaks.

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.