Fuel Capacity Question

free2wander · 09-14-2010, 09:52 AM

We have a 1999 Ultimate Freedom 40DJ. According to the spec sheet, it's supposed to have a fuel capacity of 125 gallons, but the other day we drove up to the fuel pump for our first fillup and it only took about 55 gallons. My confusion comes from the fact that the fuel guage showed only a tad more than 1/4th tank before fueling. Has any one else had this happen? Can someone shed some light?

MickBrennan · 09-14-2010, 10:02 AM

Our tank is "supposed" to have an 100 gallon capacity. We ran out of fuel in Kentucky, coasted to the pump and filled to the top with 87 gallons.

That was pretty amazing because the gauge read just over 1/4 quarter full. Several previous fill ups took 84 and 80 gallons. We were close to the edge! It seems (now that we pay attention) that the top half of the tank is WAY bigger that the bottom half.

CC38EL · 09-15-2010, 10:57 AM

Our experience is inverse to yours. On our Ultimate Advantage (100 gallon tank), once we fill up, the gauge will stay on full (pegged right) for 250 miles. Then it will make its way down to 1/2, about 400 miles.

After 1/2, we start looking for a fuel stop. It's almost as if the gauge is connected to the rear wheels. For each rotation, the gauge falls off. It's pretty quick to empty.

But empty is fairly accurate. I've put 85 gallons in when the needle was just under the 'E'.

RVThere · 09-15-2010, 12:33 PM

Are you on a Freightliner chassis? Check with them as they replaced my fuel tank because the vent tube was not designed correctly. Before I could not put more than 30 gallons in the tank when it read 1/4 and it used to spit fuel back at me. Now I can put about 60 gallons in and the diesel shower has stopped!

robbstein · 09-15-2010, 12:38 PM

We have the 03 Advantage on the Spartan chassis. It has a 100 gal tank. When my low fuel light comes on it will take about 87 gal to fill. I do have the problem at the top of the tank that when full, it will be 200+ miles before it comes off the peg.

McDuff · 09-16-2010, 09:15 AM

Quote:

Originally Posted by robbstein

We have the 03 Advantage on the Spartan chassis. It has a 100 gal tank. When my low fuel light comes on it will take about 87 gal to fill. I do have the problem at the top of the tank that when full, it will be 200+ miles before it comes off the peg.

+1

Watching the gauge as my wife pumped, it took ~26-27 gallons more after we hit "full".

Also, my generator kept running way past 1/4 tank. I shut it off when I was getting worried about making it to a station.

free2wander · 09-16-2010, 10:24 AM

Thanks for all the replys everyone. I guess I'll just have to experiment a little. For those that asked, I do have a Freightliner chassis with the tank accessable from either side.

Again, thanks for the replies.

Eric n Karen · 09-19-2010, 10:47 AM

Your experience is very typical. Gas gauges are not calibrated, and are meant to give you no more than a general idea how much fuel you have (the same thiing applies to your car). The only way to know for sure what the marks mean on your gause is to fill the tank full, and then drive until your gauge gets to the mark you want to check, then fill up again to see how much gas it takes to get from that mark to full. Once you calibrate the marks so you know what they mean, you're all set.

phays · 09-19-2010, 07:42 PM

I use two indicators of fuel usage. I keep a note of the mileage at last fill up and use 9 mpg as the rate of fuel usage. I also use VMSpc on my laptop to monitor, among other things, the gallons of fuel remaining. These two methods depends on how sure you are that you know how much fuel is in the tank when you fill it. I find that I can easily put in 5 gallons or so after the pump kicks off the first time. I prefer to fill up at about the half tank level. So using my estimate of fuel usage, I will start looking for fuel at about the 400 to 450 miles traveled point.

My gauge stays on full for a long time and is not at the half mark when I refuel. Yet, based on how much fuel I put in, the tank is no more than half full when I stop. I've found that the fuel gauge is not a reliable indicator of fuel remaining; at least not for my satisfaction. I much prefer the VMSpc fuel usage numbers and find them to be much more accurate.