modless tank capacity - Diesel Forum

achowell · 01-03-2009, 04:26 PM

havnt done any mods on my fuel tank at all... when i fill up i just let it go till it clicks off then im done i dont try to squeeze anything more into the tank... how many gallons am i probably getting in there?

catch&release · 01-03-2009, 04:56 PM

Don't know about the short beds with the 29gal tank, but mine (38gal tank) will hold another 4 gallons after the nozzle shuts off and the foam goes away. I have no idea how much more the fill tube will hold (beyond the 38gal tank), probably a gallon or so.

achowell · 01-03-2009, 05:26 PM

i hav the 38 gal.

alexjeep · 01-03-2009, 07:23 PM

On my short bed with the 29 gallon tank I can get anywhere from 3-5 more gallons in the tank. It takes a while though. Would like to do the harpoon mod, but it is way to cold outside right now. Also I don't have too many friends that are mechanically inclined to help me drop the tank.

achowell · 01-04-2009, 02:52 AM

use a floor jack and a couple of ratchet tow straps.

SmokeyWren · 01-04-2009, 11:56 PM

On April 2, 2002 I came in on fumes. My truck took 42.8 gallons to fill it up through the foam to have liquid diesel at the cap.

At most truck stops, after mine shuts off with the automatic fuel filler shutoff, I can dribble in another 4.5 to 5 gallons. 42.8 minus 5 gallons is 37.8. Therefore, if I don't dribble in that last 5 gallons or so, then my 38-gallon tank holds at least 37.8 gallons. But if I take another 10 minutes to fill it to the cap, then it holds at least 42.8 gallons.

Since my engine was still running good when I stopped to fill up, I don't really know how much longer it would have run. But not much, I'm sure. So WAG 2/10ths of a gallon, and I'll say mine holds 38 gallons if I don't add more after the automatic shutoff clicks off.

But 43 gallons if I do my normal fillup with liquid diesel at the cap.

doczenith1 · 01-06-2009, 01:40 PM

I also did some experimenting back in 2002. My results are for a gasser but should be similar.

I loaded a 5 gallon gas can (with 5 gal of gas) in the back of the truck and headed out for a weekend trip. On my way home I purposely ran out of gas. After pouring the 5 gallons of gas into my tank I drove to the nearest gas station which was only two miles away, thus not using much gas after running out. I made sure to fill the 5 gallon gas can to the same level as it was before filling my truck on the side of the road. Here are the results.

8794 - low fuel light comes on, overhead display (OHD) says 27 miles to empty.

8813 - OHD says 10 miles to empty.

8832 - OHD says 0 miles to empty. (wow 10 miles = 19 miles…)

8866 - ran out of gas, OHD says 16.1 mpg. (70 mph…must have been a tailwind!!)

Now, I reset the OHD when the low fuel light came on, to get the correct gas mileage for the last few gallons. This will be used to calculate the number of gallons left in the tank when the low fuel light comes on. You will notice the 'OHD - miles to empty' gets a bit confused when the fuel level gets low. From my calculations, there is about 4.5 gallons in the tank when the low fuel light comes on based on 16 mpg. I've found that the OHD runs about .5 mpg high, so the 4.5 gallons is conservative.

It took 29.3 gallons to fill the gas can and the truck. This is to the point where the pump automatically shut off. The most I've trickled in after the pump shut off is about 4 gallons.