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When Is Empty Empty?
On my way to Lakeland FL for the Carlisle Event I pushed my fuel a little.
I have what Prevost calls a 208 gallon capacity. I do not know if that is actual, or gross. On some listings it suggests that is a 100% value but actual real world contents may be 90% of that value.
Anyway I put 1034 miles on my full tank. In addition I ran about 10 hours of generator and a similar amount of Webasto and I can only guess they consumed 8 or 10 gallons combined.
I hit the empty mark on the gauge about 3 hours prior to refueling which was about 180 miles from my fuel stop. I expected to see a low fuel warning. It never came. When I stopped to refuel I took on 175 gallons. If the capacity in the real world is 208 gallons I had a 33 gallon margin. If the real capacity is 10% less than I had 208 gallons minus 20.8 or about 187 gallons or 12 still in the tanks.
The is the most I have ever added in this coach. On a previous coach with 298 gallons capacity I once added 235 gallons.
Anybody have some insight on what we really have for useable fuel on board? As a benchmark I consider Webasto and Generator to each use about .4 GPH.
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13 Replies
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Jon,
I have some experience with this because of an inaccurate guage. When I picked up my coach after purchase we drove from Panterra to Mckinney. My first tank ran dry as I was pulling into my first fuel stop about 50′ short of the pumps. The guage was showing more than 1/4 tank. Since then I have tried to figure the usable gallons. I believe 208 is gross and almost impossible to actually fill to that level. I can’t give the type of numerical evidence you usually generate, but my experience is 90% usable is slightly optomistic and real world could be as low as 85%
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That’s valuable information George. First, it suggests each coach may have a different gauge reading so my empty was not, and your 1/4 tank was not. I was using close to 10 gallons per hour so when I hit empty and drove three more hours I had at least 30 gallons on board.
I based my guess as to my endurance on my historical fuel usage, a guess at the fuel consumed by the genset and Webasto and 90%.
Prevost once made the comment at a seminar a long time ago they set the fuel gauges to read low, something you have proven is not necessarily true. Running out of fuel is not a good way to find out how accurate the gauges are. I got a little gutsy because I knew 208 was a realistic number, but I was guessing at how much I would take on at the fuel stop based on almost 9 years of fueling records and distances covered. If your 85% is closer to real world I had 2 gallons left when I refueled.
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With my ’88 coach I believed we had the larger 250 gallon tank so when the gauge showed empty and we had only traveled 1000 miles I figured the gauge was wrong. Decided to hang out in the right lane just in case. As an exit came up I felt the engine hiccup and immediately exited, wiggled the coach a bit in hopes of getting some fuel to the pump and rolled up to the gas pumps. The coach took 203 gallons of the 208 (I learned) gallon capacity.
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I have been studying my fuel gauge recently as I am in a new to me coach. It’s an H3, so take with a grain of salt when translating to XLII. I suspect the shape of the tanks are different between the two models.
My observations:
+ My H3 fuel tank is listed as 230 gallons with a disclaimer on the fuel door that 200 gallons is the “working limit”.
+ Gauge on my XLII seemed more linear. XLII would stay on full for several hundred miles before starting to drop. The H3 drops faster from full. It also lingers around 1/4 tank longer before dropping.
+ 1/4 tank indicated on H3 is really 1/3 full. This supports what Jon said about the gauge being biased to read low.
I’m indicating 6 mpg on the DI Computer and actually averaging 6.2-6.3 mpg across the last 500-600 gallons, so that translates to a little more than 1200 miles per tank. I try to never exceed 1000 miles since last fill. I will continue to monitor as I burn more fuel.
That’s my story. Your experience may be different, but wanted to share my observations.
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I’ve asked Robert Hitt from Prevost to enlighten us.
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I put 184 gallons in our coach once; presuming 208 capacity. The last few miles the Low Fuel light was coming on as I went up small hills and then once I was level or going downhill it would go out. I was headed to a Travel America in Missouri traveling on I-44 with a clear road ahead.
When full, I think I can go almost 300 miles before the needle moves off the “full peg”. Then seems to be somewhat linear until it gets to the 1/4 mark and then seems to speed up.
It looks to me like the engine computer can calculate how much fuel is used; it calculates mileage. It would be nice to have a gauge with a “reset full” button, and then see full used since reset and/or amount of fuel remaining in gallons.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
Dick,
I think you can reset the gallons used by resetting the “Average MPG”. I’m thinking this is a calculated value for usage, but may give you an idea.
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Took this today of an ’06 Royale XLII we are in negotiations to purchase.
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You are all very brave men 🙂
Over the years of coach ownership I would push those extra miles just to save 5c or so . Man was I stressed those last few miles thinking what a dope I would be if being cheap caused me to be on the side of the road . Obviously, you were all risking a side of the road visit for Science so your stress level must have been low 🙂 and not even your wives would have called you a … 🙂
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I may have been oblivious to what might have been a real risk.
George’s post certainly got my attention because if that is my real world tank volume I was dangerously close to running out. If the frequently repeated statement that the real volume is 90% of the rated capacity I had some margin. At 85% I was in troube. If it is really 95% I can easily drive 3 hours with the needle pegged on empty. But others cannot expect that because it appears not all coaches are the same.
I do not have the sticker shown in the photo above, but if I did I probably would have pushed further and been in trouble. There is no doubt in my mind about how much fuel I used because I have records of all 31 years of coach refueling and based on annual summaries of miles driven and fuel burned this coach has historically gotten 6.5 MPG. The unknown, even now is how much fuel do I really have when the pump shuts off, how close to the bottom is the fuel pickup tube, and why did I not get a low fuel alarm.
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XL with 208 gallon tank. I always figured I am getting it about 90% full. My gauge stays near full for way over 400 miles and then drops steadily. When it is laying on 1/4 pretty solid, I add between 150-160 gallons. Either my gauge at 1/4 is reading too much fuel Or I am getting in more than 90%.
One anomaly on mine. Obviously, the generator pick-up tube is higher than empty to keep the generator from running the tank empty. I have only run the generator low on fuel one time and it was a hot day with nearly 3/8 showing on the fuel gauge. My pick up tube must be higher. Lesson learned.
Davy
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My bus has a decal showing 268 gallon capacity.
Royal added the 60 gal auxiliary tank. I wanted to get to a 10 cent cheaper fuel but decided it was too big a risk as the gauge was on empty. Added 238 gal at the stop for fuel. At 90 % that is 241 gallons. I was close to empty if only able to add 238 gal. The tank also spit back at me when it cut off.
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George,
I could never get my 97 Royale full to fuel capacity, the aux tank was mounted vertical and had to gravity feed from the bottom cross over line. I suppose if you had lots of time to keep topping off you could get there, but the trucks won’t be happy waiting behind you.
Mike Harper
2004 Marathon XLII
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