Low fuel warning

[Chadrock]

We get nearly 10 miles per gallon (ranges from 9.71 to 10.2 mpg) and our low fuel warning came on at 740 miles into our full tank of diesel fuel today.

Our 2017 Tiffin Phaeton 40AH is supposed to have a 100 gallon tank. If we started with a full tank (filled it myself) and our range is near 1000 miles, then deduction would indicate our low fuel warning comes on with over 200 miles to go. Does that make sense?

[Lt Dan]

Originally Posted by Chadrock

We get nearly 10 miles per gallon (ranges from 9.71 to 10.2 mpg) and our low fuel warning came on at 740 miles into our full tank of diesel fuel today.
Our 2017 Tiffin Phaeton 40AH is supposed to have a 100 gallon tank. If we started with a full tank (filled it myself) and our range is near 1000 miles, then deduction would indicate our low fuel warning comes on with over 200 miles to go. Does that make sense?

The fuel warning is going to come on with about fifteen to twenty gallons left. You NEVER want to run out of fuel since that can create all kinds of issues with the lift pump, so we start looking when we get down to 1/3-1/2 of a tank. In addition, you can't run the generator when you get below 1/4-1/3 of a tank and you can never get the tank totally full. If you are getting that kind of mileage, then you are extremely lucky. We are averaging about 7.5-8mpg with the same size coach. You can't base your overall mileage on what the LBCU shows. The only way to get accurate mileage is to look at overall fuel usage over several thousand miles.

[Chadrock]

Lt Dan: Thanx for the reply. What you wrote makes a ton of sense. We know never to run out of fuel and that our generator won't run at about a quarter tank.

We have the app Gas Buddy set to diesel fuel and knew today that we could save 20 cents per gallon if we drive an additional 35 miles. I know that 20 cents isn't a big deal when discussing a quarter million dollar vehicle but we like to save where we can.

You said that the warning comes at 15-20 gallons. My wife said to play it safe and figure ten gallons remaining to travel within 90-100 miles for the best fuel up option.

Thanx again!

[lllkrob]

How are you calculating your fuel mileage? I have never heard of any 40' Phaeton getting 10+ mpg for a tankful of fuel. Are you relying on the dash readout for trip fuel mileage? If so, this readout is never close to actual mileage. The only way to calculate actual mileage is to fill the tank and record the mileage then drive till the gauge reads 1/4 tank and refill the tank and record the mileage. Divide miles driven by gallons used and you will find you are actually getting about 7.5 to 8.0 miles per gallon. In 38,000 miles of driving in all types of conditions I am averaging 7.88 MPG.

[Chadrock]

I have been using the subtraction/division method you outlined. The on screen display usually shows a half gallon or so difference (always higher).

The screen is fun to look at but I prefer using a calculator.

BTW, we have only 6500 miles on the Phaeton but it has performed around 10 mpg for every tankful except when we towed our pontoon. But not towing, we have driven 70 mph in North Carolina and Kentucky, up and down the steep grades on highway 64 in West Virginia and our usual 63 mph in our tiny hills of Michigan and have gotten the same results.

We were told we would get 6-8 mpg when purchased. That has been the standard line for all four coaches we have had.

[jlturner]

There is a good write up by Crusingator. Because of the odd tank design the fuel gauge is NOT accurate, as I can attest to. :-(

[nctox]

Keep in mind that even though your fuel tank is rated at 100 gallons, you won't be able to get that much into it. Due to plumbing and other things, you may be getting only 90 to 95 gallons into the tank, even though you think you can't add any more without it overflowing.

[DeWat]

I hope I don't sound critical, but running it low then relying on a gas (fuel) app is playing a very dangerous game. Things you want to consider that an app is not going to tell you...

- station accessibility given the size of your motorhome
- volume of diesel sold (stay away from slow sales locations)
- accessibility of streets leading up to and away from the station
- amount of business at the station (kind of like station accessibility, too much auto traffic to safely manuever)
- (already mentioned) being able to maintain creature comforts, i.e. run your generator while looking to refill

The cost of fuel starvation associated problems have caused many to just play it safe, and start looking after crossing the 50 yard line (half tank). You don't need to actually be burned to know that playing with fire can burn.

Again, not being critical, just giving ideas on what can happen.

[garykk]

We have a 2014 QBH, this last trip home we ran the Mh down to 1/4 tank on the gauge (something I usually don't do). when I filled up it took about 64 gallons.
Our mileage has been around 8.5 on average. 30k miles on it.