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Old 08-22-2019, 06:54 AM   #1
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Join Date: Aug 2013
Location: Haslet, Texas
Posts: 310
When do you stop to refuel?

Hello everyone, we are still new to Newmar only having the DS a couple of months. We’ve put about 3000 miles on so far and I’m still trying to wrap my head around all the switches and gauges. Everything is going very well but; I had a question about refueling or more correctly when to refuel?

It’s the middle of summer, so we run the generator for the A/C’s while going down the road and average in the high 7’s to the low 8’s for mpg and have a 150-gallon tank. Our fuel gauge I’m pretty sure is a joke, as I am never able to put anywhere close to the same percentage of fuel as the gauge. If the gauge is at ½ I can maybe put in 50 gallons, so it looks like I am going to switch away from the gauge to doing the math to calculate needed fill-ups. Also, my understanding is the generator shuts off at ¼ of a tank? But I don’t where the ¼ is measured from, please let me know?

Simple basic question is when do you refuel? Doing the math, I can go about 1000 miles on a tank but so far, I think I’ve filled up at 500ish miles just because I don’t want to chance it, but I would like to safely stretch that out a bit.

Same question for DEF please.

2013 Newmar Dutch Star 4318
2019 F150 KR
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Old 08-22-2019, 07:04 AM   #2
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Winnebago Owners Club
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Location: Jacksonville, Fl
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I start looking for fuel at about 1/2 tank - or since your gauge isn't accurate, at about 1/2 of available miles traveled. That's actually a bit earlier than I might, but my generator runs out of fuel at just under 1/2 tank according to the gauge. Since we nearly always travel with the generator running we make a point to fill before then.
Given my druthers I'd start looking at just under 1/2 tank and would definitely find a place by 1/4 tank.

Your generator will quit drawing fuel at ABOUT 1/4 of tank, but it has nothing to do with the gauge. The pickup tube for the generator is set higher in the fuel tank than the pickup tube for the main engine, to prevent the generator from running the tank dry and leaving you stranded. Exactly where it quits depends on exactly how long the pickup tube is. It could be a little high like mine, or it could be lower. That's one of those things that the only way you can know for sure is to let it run someday until it quits. Just make sure you're close to a gas station when that happens.

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Old 08-22-2019, 07:13 AM   #3
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You are assuming you can get 150 gallons into your 150 gallon tank. Very bold. Most stated tank capacities are bogus. That 150 gallons includes head space which never has fuel in it. I believe I can get about 85 gallons into my 90 gallon tank on a good fill.
2006 Monaco Safari Cheetah 40PMT
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Old 08-22-2019, 07:20 AM   #4
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1/2 tank is when I like to fill as well. Good time to stretch the legs, use the potty, etc anyway. Multiple birds. I like to keep the diesel tank fairly full. As full as possible for extended stops.

I don't like to keep the DEF tank extremely full - so I am rarely above 3/4 there. There is DEF discussion in another thread posted the last couple of days. I am trying something new there - as suggested at Camp Freightliner. An external 5 gallon HDPE plastic jug and a battery operated pump. Fill DEF from jug - restock at pump on your next stop. Eliminates the need for me to pull up (to the back of coach) for the DEF fill.

Always try to fill-up at the end of the day if I can as close to the last stop for the day. I like starting a travel day off with a full tank, and if you are going to be stopped for a while, it cuts down on the room for condensation/algae growth, etc.
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Old 08-22-2019, 07:21 AM   #5
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Like you, we generally run the gen set while traveling down the road. The only exception is when the temps start staying in the low 80's and below.

My tank is only 100 gallons and my gauge is relatively accurate.

We travel anywhere from 300 to 400 miles a day. On occasion we have pushed it to 600 but that is extremely rare. I fuel each and every travel day, generally when my tank is close to half full.

There are a couple reasons I do this. First of all I never want to get caught in a situation where my tank is right at 1/4 and all of a sudden traffic comes to a standstill and we are stuck for 3 hours on the interstate with no generator. Secondly, by only adding a half of a tank at a fuel stop if I would get some "questionable" quality of fuel it will be mixed with what good fuel is already in my tank and maybe not cause me a problem, as compared to almost topping off my tank with bad fuel.

I also plan my fuel stops the night prior to a travel day. I use several apps to do this plus I check the satellite view of the station I'm going to use. I like knowing how to enter and exit the big rig diesel lanes prior to taking the exit for my fuel stop.

As far as the DEF, I got tired of checking for broken seals at Walmart (and finding them) so now I always purchase my DEF bulk at the pump. I keep a 2 gallon DEF container in my bay, fill it, put it back in the bay, then add it to my DEF tank later at the campground. I'll do this for a couple fuel stops then skip one. Anyway, I keep timing it so my DEF tank always shows around 3/4 full.
2017 Newmar 4369 Ventana
Toad: 24' enclosed w/Harley, Mini Cooper, Kayaks
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Old 08-22-2019, 07:37 AM   #6
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On our 8.3 325hp Cummins I get around 7mpg. I also have a 150 gal tank, which I recently changed out the fuel level sending unit. It is pretty accurate now. I travel 300 miles max per day and I hit approx 1/2 tank at the end of the 2nd day of traveling. When I fill up I put in about 75-80 gals.
I know nothing about DEF, sorry.
Rick and Larrie Dee
1997 40' Newmar London Aire DP CTA 8.3 (Mechanical) 325 Spartan MM
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Old 08-22-2019, 07:42 AM   #7
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Our previous coach, a Dutch Star, also had a 150 gal tank. I agree with TonyMac to allow for head space, so 150 x 95% = 143 gal max. Averaging 7 mpg ( I actually averaged 7.5) to be conservative, my range was 1,000 miles. Although I could run two 350 mile days consecutively leaving 43 gal, or 30% reserve, I would normally fill up every day near day's end. I also like heading out in the morning with a full tank and never had to worry about my generator cutting off.
Our current coach tank capacity is listed at 109 gal, so that changes refueling strategy a bit.
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Old 08-22-2019, 07:44 AM   #8
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My fuel gauge behaves like everyone else's (not accurate) but does gain accuracy as the tank goes down. Needle seems to race to half tank quicker than it should but certainly slows going from half to quarter. Also as another poster mentioned, I would think our 150 gal tank probably has a usable of maybe 140 gal? I hate fueling so I typically stop at around a quarter full & can take 80-100 gal.
Bill & Kelli 2015 Dutch Star 4366
2002 Safari Zanzibar 3906
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Old 08-22-2019, 07:54 AM   #9
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So far the majority of our travels are in the West, Canada, and Alaska where gas stations can be few and far between in places.

I prefer to full up at half a tank partly to prevent the anxiety of running low while still searching for a fuel stop, and mostly because the burning the first half tank takes about 4 hours and by then its time for a rest stop as well as fuel.

Here on our current trip we're using the Pilot/Flying J app. It shows exactly where we are and exactly where the next station is. Great peace of mind!
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Old 08-22-2019, 07:55 AM   #10
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I start looking for a gas station at 1/2 tank level. I keep track of miles traveled after each fill up and divide by 6 or 7......to guesstimate how many gallons have been used.
2003 Dolphin LX 6355 w/ W22 chassis; 8.1L gas & Allison 1000
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Old 08-22-2019, 08:14 AM   #11
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I have the 150gal tank. We do 500 mile days. I routinely run mine until the low fuel light shows, then I add fuel. This is around 890-1000 miles. So every other day.

The most fuel I have put in is 136 gallons. The generator was still running. Never hit the generator cut off, and I believe that Newmar has plumbed it to where it will suck the tank dry.

My 2008 fleetwood would cut off the generator when it was at 1/4 tank, but neither of my 2 Dutch stars have ever cut out due to fuel.

NHSO (Newmar Hoot, Sevierville Original), Kindness Matters
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Old 08-22-2019, 08:17 AM   #12
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We also have a 2013 DS. When I picked it up from the dealer a day or so after it was delivered from the factory, I didn't pay attention to the fuel gauge as I drove off. I live 100 miles from the dealer and as I was approaching my home, about 25 miles away, the fuel warning light went on. They gave me a coach that was pretty much on empty ! I made it home and the next day I went to get fuel. It took 120 gallons, so that tells me the warning lamp goes on with about 30 gallons left.

So now, I just look at the fuel gauge and when it gets under 1/2, I then look at the FUEL USED display on the LBCU. I find it is about 10% under actual usage, so I stop when I've used 80-100 gallons or when convenient, like at the end or beginning of the day. Typically I only use Pilot/FJ for fuel and plan my fillups accordingly.

I haven't had the genset shut off due to low fuel yet ( I didn't try it on the day I picked it up and the warning light went on) and I typically run until the gauge shows 1/4.... but as I said, that usually shows about 100 gallons used on the LBCU for 1/4 on the gauge is really more like 1/3 of actual usage.

For DEF, I get DEF at the pump. I carry 2 one gallon DEF containers that I fill at the pump due to the DEF fill on our year coach being on the other side. Then either at the campground of next fuel stop I put the DEF from these 1 gallon containers into the DEF tank. I keep the DEF tank topped off , since my fueling is usually about 100 gal of diesel, the 2 gal of DEF is just about right for that fuel usage.
2013 DS 4338
2015 F-150 toad with kayaks,bicycles and a Harley in the back
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Old 08-22-2019, 08:40 AM   #13
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We drive on the top half of the tank! With our coach, both the fuel gauge and the light bar display percentage indicator are reasonable accurate and agree with one another. At each fuel stop, I check the percentage indicator and estimate how much fuel we'll need. Can't remember a time when the estimate was more than 10 gallons off.

For the DEF, we fill when the indicator drops to two bars. Again, that's at about the half-full point. Driving on the top half of the tank provides us with the peace of mind that we don't have to worry about running out.

In miles, our fuel refill point is about 500 miles and our DEF refill point is at about 1,500 miles. So, every third fuel stop we refill the DEF.

Jim (W7DHC), Diane & Mini Schnauzers, Lizzy & Ellie
2018 Mountain Aire 4047 + 2014 Honda CR-V "toad" w/AF1
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Old 08-22-2019, 10:43 AM   #14
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Following. I have much to learn. Question: 150 gallons of fuel weighs north of 1,200 lbs. Has anyone measured mpg at full versus 3/4, 1/2 and 1/4? Topping off daily may not be the most efficient way to travel cross country. Then again, the three most useless things in aviation are the runway behind you, the altitude above you, and the air in your fuel tanks...

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