Fuel tank capacity

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Ned

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How is the capacity of a fuel tank measured?  Is the stated capacity the usable gallons or the total size of the tank?  If the latter, is there any way to determine the usable capacity short of running the tank dry?
 

Ron

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Good question Ned.  In many cases it is the total capaity of the tank without considering the required expansion space or how far the pickup line is from the bottom.  However. the original tank on our Eagle was replaced under a recall and we went in with the gauge reading empty.  When they drained the remaining fuel they measured 15 gallons.  After completion of the work they filtered and reinstalled the 15 Gallons they had drained.  We drove to the stations and put in 146 Gals so I suspect that we have 150Gals usable in the Eagle.

I have been told that some manufacturers do list the fuel capacity as the useable fuel while others do not.
 

Ned

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So the answer is it depends :)  I really would like to know if my 90 gal. is usable or total.  The most we've ever put in was 78 gal. and the low fuel light was on and I don't want to run it dry to get an accurate number.  I think I'll post the question to Freightliner.

Wish we had 150 gal. on board.
 

Gary RV_Wizard

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Usually the number they give is the rated capacity supplied by the tank manufacturer, not actual usable capacity in that application. And of course the gauge reads "empty" before the tank reaches bottom anyway, to leave a reserve.
 

Ron

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Wish we had 150 gal. on board.

It is nice till you fill up after a 1000 mile or so, then the big bucks don't look so good.  But then it is better than the bill Tom gets when filling his water RV. ;D ;D
 

Ned

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Even driving on the top half of the tank this summer, we had some near $200 fillups :)

I've sent an inquiry to FL about my tank capacity, but I suspect Gary is correct.
 

BernieD

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Ned said:
So the answer is it depends :)  I really would like to know if my 90 gal. is usable or total.  The most we've ever put in was 78 gal. and the low fuel light was on and I don't want to run it dry to get an accurate number.  I think I'll post the question to Freightliner.

Wish we had 150 gal. on board.

Ned

When we had our FL chassis, I discussed this issue with some of the FL techs. When you put 78 gallons in you were pushing the limit. It isn't just the tank running dry but also all the crud that builds up in the bottom of the tank. That can clog up your filters real quick. FL's recommendation was to avoid getting into the last 10-15% of the tank. If you can remember your gauge needle position when you took 78 gallons, use that as your must refuel point.

As Ron said, 150 gallons is nice but after you drive for 1,000 miles and then fill up, you get sticker shock.
 

BernieD

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Ned said:
Even driving on the top half of the tank this summer, we had some near $200 fillups :)

With our 150 gallon tank we had a few $300 fillups and 1 $400 one. Gulp :-\ :-\
 

Ron

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I suspect Gary is correct too in most case and prior to the event I mentioned I thought that was or case. We seldom plan on fuel stops depending on distance anymore.  I check fuel prices before the trip and plan fuel stops depending on price and a reasonable distance.  Coming down here to Tx we stopped for fuel in Oklahoma after traveling over 1000 miles but that was where the price was better than it was along our route.  


Bernie we have had some $300+ fillups but haven't reach the $400 level yet.
 

Ned

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We don't rely on the gauge but use distance and availability (and price) to schedule our fills.  We've found that 600 miles is about right between stops, unless we can save by buying before crossing a state line.  That gives us at least 2 days of driving between fills when we're on the road.  Of course, we always top off when we're parking for any length of time.
 

King

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In my little class B, the chassis manufacturer's manual said 30 gal usable.  On the first trip we drove until the gauge was in the red and the little red gas pump lit up.  Filled it up, took 33 gal.  Since then, I haven't run it that low, just look for the cheapest gas when we get to the quarter mark.  (An additional note for the diesel drivers, you really don't want to run it out.  Some diesels have to be bled to eliminate airlock.)
Art
 

Tom

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Ron said:
But then it is better than the bill Tom gets when filling his water RV.

That's for sure Ron. 500 gallons doesn't last long when you're burning 80 GPH at cruising speed. Doesn't take you very far either  :(
 

Ron

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jimtoo said:
Ron, I would like to ask what kind of unit you are driving and cruising speed to use 80GPH. :eek:  I want to make certain I don't buy one.


I don't have a unit that burns 80GPH but Tom might.
 

Shayne

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Called watercraft  A friend of mine has one (Sent a pic of it to Tom) that has 1000 fuel tank and he says when opened up it may (MAY) run for 2 1/2 hrs if he's lucky and has a tail wind.  Sounds more like he needs a storm behind him.
 

29er

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When I had a Lincoln Town Car, the fuel light and gauge needle showed empty even though there was at least 3 gallons left in the tank. When I asked the local dealer all i got was hot air. So I called Lincoln direct and spoke to one of their engineers. His answer to my query about fuel left in the tank while showing empty...They (Lincoln) didn't want to see any of their cars pulled of the road because it was out of gas. Very bad image for the company. I believed him.
 

Jackliz

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Ned said:
How is the capacity of a fuel tank measured?  Is the stated capacity the usable gallons or the total size of the tank?  If the latter, is there any way to determine the usable capacity short of running the tank dry?

When driving down from Montana, Jack let the fuel tank get down to E on the fuel gauge.  I was really upset, picturing us on the side of the road, engine stopped and prime gone.  :mad:  :mad:  :'(  :'(
    BUT we actually had 20 gallons of fuel left because we filled up with 280 at the Flying J in Cheyenne, WY.  Jack promised me that he would not let the tank run so low, again. 

Talk about $300 fill up? How about $900? 

Liz
 

King

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A V12 Packard built Merlin engine in a wooden boat called "Miss Packard" was shown to burn about 60 gal/hr in the P51 Mustang fighter or the Elco PT boat it was built for in WWII.  1250 HP.
Art
 
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