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Fuel Gauge Accuracy

How accurate is your fuel gauge?  Mine seems to reflect the correct amount, compared to fuel flow, till it indicates 1/2 tank.  After that, the fuel gauge starts dropping rather quickly. When mine indicates almost empty, I have only consumed about 120 gals.  This means I have 60 gals left when indicating empty. Considering getting the system fixed when I am at FOT next month, but may not if everyone's is that inaccurate. It may be my aviation background, but I want to know exactly what I have left when it gets low.
Steve DeLange
2005 U320T 40'
Pearland, Texas

Re: Fuel Gauge Accuracy

Reply #1 –
Mine is just about the same in my 1994 U300  with a tank size of  160 gallons.
The selected media item is not currently available.
Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: Fuel Gauge Accuracy

Reply #2 –
Steve, do you have a  driver information center so you can track the two readings?  My gauge and DIC both track the same and I believe give accurate readings.  When refueling I usually level the coach and fill till I can see the fuel level at the tank spout.  I guess my obsession to cram in all i can comes from only having a 29 gallon tank on Superduty pulling 5th wheel for several years.  So it takes a long time for my gauge and DIC to leave 100 percent, but when it does it appears to track accurately.  The lowest I have ever allowed the fuel level was 1/4 tank per the gauge, 25 percent  per DIC.  Number of gallons to fill was around 130 gallons or so if I remember correctly.  Once my gauge and DIC leave 100 percent, first and second halves rate of usage appear to be the same.  I hope it would be a simple calibration procedure to get yours tracking usage properly.  Good luck!
Bill and Joyce, The House2 and Dashboard Pig III
2000 U320 4210 CAI (The House2)
Build # 5733
2019 F150 King Ranch FX4

Re: Fuel Gauge Accuracy

Reply #3 –
Mine reads accurately from full down to 1/4 tank, they drops very quickly to the top of the red zone. When the needle is in the red and just above the empty line I loose the generator. At that level I have 40 of the 180 gallons remaining and if I make a long sweeping turn the engine will starve for fuel and quit.
Scott Peatross
2003 34' U270
Stevenson Ranch, CA

Fearless ex-owner of one of the most complex motorhomes ever built, the 1987 Bluebird Wanderlodge PT40 :)

Re: Fuel Gauge Accuracy

Reply #4 –
We just had the sender replaced on our 1996 U320--- found out the hard way that it was inaccurate right after we bought the coach.  The old style sender has a potentiometer calibration adjustment on the top.  If you still have that style, you might try adjustment ( there is a procedure that Foretravel service will share with you).  The new style sensor lacks this potentiometer, but has a procedure for auto-calibration.  The sensors are interchangeable.  The new style sensor is about $100 and is easy to change (on my coach).
The new sensor gives a pretty good sense of how much fuel you have, but it's not aircraft accuracy!
It takes a while to come off full, then pretty accurate in the mid range, and drops more rapidly as you get closer to empty, at least that is my experience.  As a result I try not to go below 1/4 tank before fill up.
Current coach 1996 U320 40'
Previous coach, 1990 36' U280

Re: Fuel Gauge Accuracy

Reply #5 –
Quote from: sedelange –
How accurate is your fuel gauge?  Mine seems to reflect the correct amount, compared to fuel flow, till it indicates 1/2 tank.  After that, the fuel gauge starts dropping rather quickly. When mine indicates almost empty, I have only consumed about 120 gals.  This means I have 60 gals left when indicating empty. Considering getting the system fixed when I am at FOT next month, but may not if everyone's is that inaccurate. It may be my aviation background, but I want to know exactly what I have left when it gets low.
Here is the instructions for calibrating the Centroid Fuel Sender,
Centroid Fuel Sender Calibration
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Fuel Gauge Accuracy

Reply #6 –
What John and several others posted is common: "It takes a while to come off full, then pretty accurate in the mid range, and drops more rapidly as you get closer to empty"

Centroid fuel sender calibration: CENTROID PRODUCTS
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Fuel Gauge Accuracy

Reply #7 –
Our experience was the same as above.  We now monitor fuel using the Silverleaf product.  The Silverleaf shows Miles to empty and how many gals left in the tank.  I rarely look at the fuel gauge any more.
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Fuel Gauge Accuracy

Reply #8 –
Reality-- I fill by MILES, not gauge.  And, then, only after consulting GasBuddy.com - Find Low Gas Prices in the USA and Canada

Very easy to save $.30-.40 per gallon without going out of your way.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Fuel Gauge Accuracy

Reply #9 –
Mine has the DIC and I also fill by miles, that's how I knew the gauge was so wrong.  I just like everything to work right. Problem with just filling by miles is while I was parked for a week in 12F temperatures, I was uncertain exactly how much the generator and aquahot were burning.  Turns out they consumed about 30 gals during the trip.
Steve DeLange
2005 U320T 40'
Pearland, Texas

Re: Fuel Gauge Accuracy

Reply #10 –
To compensate for the generator factor I always fill up shortly after we leave to go to a new spot.  I also fill up before we park. 
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Fuel Gauge Accuracy

Reply #11 –
Quote from: Carol & Scott –
I also fill up before we park. 

An excellent idea-- minimizes condensation in the fuel tank.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Fuel Gauge Accuracy

Reply #12 –
As I don't trust my gage I dip my tank and that way I know exactly how much fuel I have.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Fuel Gauge Accuracy

Reply #13 –
Quote from: frozenh2o –
40 of the 180 gallons remaining and if I make a long sweeping turn the engine will starve for fuel and quit.

Same here.  The large footprint and interior baffle design of the fuel tank contribute to the sloshing on turns that causes this.  One of many several reasons it's best not to run below 1/4 tank.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Fuel Gauge Accuracy

Reply #14 –
It takes between 90 and 100 gallons to fill our "150 gallon" tank when the gauge reads 1/4 full. Therefore, it appears that the tank is about 1/3 full when the gauge reads 1/4. I don't know how many usable gallons are in the "150 gallon" tank, but I'm satisfied with the gauge's accuracy.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Fuel Gauge Accuracy

Reply #15 –
I have a spreadsheet that has an entry for all the legs of our trip(s).  We'll drive between 4-8 thousand miles a year. This year possibly a little more.
I use Delorme's Street Atlas to plot the route which gives me anticipated mileages for all the legs. I don't try for the entire trip, just the current planning horizon.
Periodically I'll take the actual odometer readings from my trip log and update the sheet to actual miles traveled.

As I log a fill up in the spreadsheet it will reset my estimated tankage to 120 gallons (my conservative figure for tank capacity) and using 8 mpg will recalculate fuel remaining for the future legs. I don't like an anticipated fuel state at the end of a leg below about 35 gallons so I'll insert a fuel stop prior to the end of that leg and use Gas Buddy to find a good fueling stop some where along the way.

I don't think I have ever taken on more than about 90 gallons at any time.

As we go along it is easy enough to change the spreadsheet to reflect future stops.
We like to have a reasonable idea where we'll sleep at night.
Elliott & Mary Bray
ex. 1996 36' U295 - Build 4879
ex. 2018 Coachmen Leprechaun 319MB
 
 

Re: Fuel Gauge Accuracy

Reply #16 –
My fuel gauge shows 9/16 when full and 3/8 with 70 gal left but never goes lower.  It's been that way since I got the coach 4 years ago. My VMSpc tracks fuel use very well.  If I haven't been using the generator or Aquahot and it says I can use 100 gallons it will be only a couple gallons different from that to fill.  I rarely get below 70 gallons and as Brett says, use Gas Buddy to look ahead for good prices and easy in and out stops.

AAA has a  really good free app for travel planning. Easy to put in any number of waypoints to get time and miles between them and good directions.  It also shows fuel stops and prices, campgrounds, rest stops and lots more.  This is one of our most used travel tools.

Roger
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN