FUEL TANK VENT RELOCATION KIT
Have you ever wanted to check your fuel mileage and tried to fill the tank so you can see fuel in the fill neck? If you have a 2003 or newer Dodge Ram/Cummins truck, you know how long that can take.
Wasted time
Dodge designed an air space at the rear of the tank that holds approximately 3 gallons of fuel. This is for fuel expansion. If you are patient, you can trickle fuel into the fill neck to fill that air space. Eventually, you’ll get the tank completely full and fuel will show in the fill neck. I was curious how much extra time I had spent topping off. I filled up exactly 40 times in the first year I owned the truck. After the pump clicked off, I averaged 8 minutes to fill the truck to the fill neck. Doing the math, 40 fillups X 8 minutes = 5 hours and 20 minutes standing in the cold and heat waiting for the tank to fill! I could have been 8 minutes down the road instead of standing by my truck dutifully topping off to keep accurate records. There had to be a better way, and I wasn’t going to cure my obsession with fuel records anytime soon.
The solution
I dropped the tank to take a look. The factory vent enters the tank on the lower part of the tank. When fuel reaches the factory vent, the tank becomes difficult to keep filling. I figured that if I relocated the vent to the highest part of the tank, it would fill to the same level I was filling it to, but in a much shorter amount of time. I used a hole saw to cut a hole in the highest part of the tank and installed a bulkhead fitting. I then ran a new ¾” vent line to the factory metal vent line that connects to the fill neck. I capped the factory vent line and re-installed the tank. Sure enough, the tank filled up within 40 seconds after the pump clicked off!
A word of caution
After some research and tips from other members on the forums, I’ve learned that there are some cautions that should go with this modification. Diesel fuel has a thermal expansion rate of .00046 gallons per degree Fahrenheit. Lets say your diesel fuel comes out of the ground at 50 degrees F, and you fill your tank and park your truck in the summer Arizona sun while you go eat lunch. You spend an hour inside and return to your truck where the fuel has had a chance to heat up to 100 degrees. If you put 35 gallons in your tank, and the temp changed 50 degrees, your tank of fuel will expand by .805 gallons. If you don’t burn that fuel off before it warms up, or leave an air space, it will expand and you could possibly have a leak. The walls of the tank itself may expand with the temp change, the sides could bulge outward as the fuel expands, but it might be wise to keep this in mind if you find yourself in the above situation.
I figured that other members would be interested in this fix, so I put together a kit that has all you need to do this modification yourself. It comes with ¾” abrasion resistant hose, a bulkhead fitting, hose clamps, and fittings to connect it all. The kit for long bed trucks is $35 + shipping and for short beds, $30 + shipping. The modification takes an average of 3 hours to complete. Please visit the learning center for detailed instructions with pictures to guide you through the install.
Additional information can be obtained from InnerTruck.com or call us at (812) 656-8223 or dmkelley@fuse.net