Garmin gps fuel gauge

T

trailertrawlerkismet

Well-known member
Joined
Feb 23, 2011
Messages
2,519
Fluid Motion Model
C-24 C
Vessel Name
(2022) Kismet
On our R25OB I’m have fuel tank level issues with the fuel level on the Garmin display. Prior to my fill up I thought the fuel needed to fill up the tank would be 80 gallons. At the time the Yamaha display told me I had 1/2 tank but the Garmin was at 20 gallons. I filled the tank and it would only take 47 gallons. I went into the Garmin system and clicked on the “full tank” icon. Fast forward 40-50 miles and 2 weeks later and the Yamaha gauge to only down 2 bars however the Garmin shows slightly less then 1/2 tank. I put a flashlight light onto the tank and can see that the Yamaha gauge is accurate as the fuel is only down slightly. I call Garmin on Monday but in the meantime I wanted to ask if any owners have experience the same problem and what the cure was?

Jim F
 
Same thing on the 8612XSV on our R27OB, which i believe started after the most recent update (2024.0103). I recall Submariner mentioning it a while back, as well.

I have not contacted Garmin but from second-hand accounts of people who have, it looks like Garmin is aware of the issue and say they will fix it in a future update.
 
It's a bug that started in 33.00 code on Garmin. Affects the 8612 and other chart plotters. It's specific to Yamaha and Garmin. Garmin knows about it, has identified the issue. They've said they'll be releasing a fix for it this spring (which I assume is any day now, since v34.00 was released early January and nothing has been released since January).

This is not a Ranger Tug issue. It's a Garmin and Yamaha issue as it also affects boats such as Pursuit, which have Garmin electronics and Yamaha outboards.
 
Until they release new software, here's how I work around this bug.

Before I leave the dock, I always reset my Trip Odometer and Trip Hours, and Trip Miles.

When I get back to the dock my chartplotter will say something like
Fuel Used: 37.3gallons
Trip Odometer: 29.6nm.

I take 37.3 and divide by 2 = 18 gallons.

I then will do "add fuel" and instead of "fill up all tanks" like I normally would do... I just add 18 gallons to the fuel tank.

That corrects my "Total Fuel Remaining" number so it's accurate on how many gallons of gas I really have in the tank. That sets me up for the next trip.
 
Quick update regarding this Garmin onboard fuel error. They released an update a few days ago (v35.10) that did not fix the issue.

I chatted with a Garmin rep today who could only say,"We are planning on releasing a patch in a future software update."
 
Pandion":c5de388k said:
Quick update regarding this Garmin onboard fuel error. They released an update a few days ago (v35.10) that did not fix the issue.

I chatted with a Garmin rep today who could only say,"We are planning on releasing a patch in a future software update."
Click to expand...

The fix is still being tested. Garmin said they've slated it for a Q3 release (like, July/Aug/September) timeframe.
 
The Garmin fuel gauge has been Fluid motions fall back fuel gauge for accuracy. And the fuel tank sender has been calibrated using full tank calibration. This is inaccurate with an irregular shaped tank. For years the analog fuel gauge and sending unit have been unreliable and inaccurate. Today we have electronic EVC monitors that convert fuel tank percentages to gallons. All engine manufactures of modern day outboards and inboards have some type of electronic monitor. Todays fuel gauges and sending units can be accurate. The prerequisite for an accurate reading is the boat must be in a level running position ( especially TUGS and CUTS because the sending unit is far aft on the tank ) and the sending unit must be properly calibrated. Again using full fuel tank calibration is not accurate!! It will give you a estimate at best.

Example: Jim Favors post. His Yamaha fuel gauge showed 1/2 tank. He took on 47 gallons and most likely had a few more gallons to go before the tank went to over flow (full). At a 10 gallon error that is just over 10% off. In the wrong way! If my fuel gauge is reading 10% more than I have in the tank that worries me. If the gauge is reading 10% less than I have in the tank. I know when it reads 1/4 of a tank I have at least 20 gallons + 8 to ten gallons. When boating, redundancy is always better. If you have two ways of checking fuel that are both known to be accurate with in a few % you can check one against the other.

Using the Garmin as a fuel gauge is an ok method but it is not always accurate. It relies on the captain to enter the exact amount of fuel pumped into the tank. If this entry is incorrect then the Garmin only has information based of fuel burn. It has no idea how much fuel is in the tank. It has no reference. What you entered is the only reference it has. If you know exactly to the gallon how much fuel is in the tank and the Garmin software does not have a glitch, or the N2K communication is not interrupted. You will have an accurate fuel reading. If you have an fuel tank sending unit that is properly calibrated then you have a secondary means of knowing how much fuel is in the tank. They should match up. If they don't match up which one do you rely on? For me I rely on the one that reads how much fuel is in the tank. Then I rely on my own calculations. My log book is my way of proving accuracy. Hours run, average fuel burn at a given speed = gallons used. I use the chart plotter fuel burn information because it is easy and seems to be accurate to a degree.

When I had my C26 the EVC Volvo backboned to the Garmin I found after two years of boating that the Garmin reading was off by 13.5 gallons. The Garmin showed I had 31.5 gallons in the tank. The Volvo EVC fuel gauge showed I had 57 gallons of fuel left. Which was right? I drained the tank to confirm which was right. After draining the tank into a marked 5 gallon container then pouring the fuel into a 55gallon drum I measured 45 gallons of fuel in the tank. Both gauges proved to be inaccurate. At that point I decided to properly calibrate the fuel tank sending unit. I have explained this several times on TugNuts. It is easy to do and should be done as part of a Quality Control item from the quality boat builder when the boat is delivered to the owner. Again, the full fuel tank calibration is worthless with an irregular shape tank.

After my calibration was done I relied on my fuel tank sender over my Garmin. I found it to be spot on. When I filled the tank I would use the Volvo gauge has my fill point. I would compare it to the Garmin with hopes that they both agreed. They agreed at the beginning but as time went on the Garmin would show a larger amount used. Its accuracy was repeating what I had experienced before. I would make adjustments to the Garmin based on what the fuel tank sending unit was telling the EVC. This helped maintain the Garmin's accuracy over time.

The link below illustrates the comparison Garmin reading fuel onboard and the EVC fuel sender with proper calibration. You will notice that the boat is operating at a slow speed and the boat is level in the water. The Volvo was calibrated by percentage of fuel and it will show the tank level as a analog reading or gallons. In the picture below it is showing gallons in the tank. In this photo both Garmin and fuel gauge agree within .7 gallons. I can live with that.

I'm not indicating that the Garmin is not a good tool to have. It is a great tool as long as all the holes in the cheese are lining up. I'm also not saying that the fuel sending gauge is 100% accurate but if calibrated properly it will give you a low percentage of inaccuracy. Something to use as a checks and balance and a redundancy accurate reading. When one is inaccurate then use you log book to compare. In my experience the Garmin over time becomes less accurate. The fuel gauge stays the same.

I'm back to old school now. My Pilot 34 mainship is direct injection. Fuel injected by the injector pump. There is no fuel burn monitor. I must use log book calibration and fuel tank level readings to know how much fuel is onboard and used. It has an analog fuel gauge which is old school and not accurate. Calibration is done by bending the float stick! I do have the most accurate fuel gauge onboard though. It is a pre measured stick with 5 gallon increments. Using this I know the exact amount of fuel onboard to the gallon. matched with my log book I know GPH and MPG to the exact amount. Old school but accurate, nothing to break no guess work. A 4' fiberglass stick!!!

I know this has nothing to do with the up coming Garmin update. It is my experience with electronic fuel readings compared to fuel in the tank gauge. Having both accurate is a plus when boating, Checks and Balances!!
 
This is one reason I've declined recent updates. My Garmin still calculates fuel accurately. I often wonder what else I might be missing by not updating, but ignorance is bliss and being a troglodyte has benefits. Anything crucial in those updates worth trading off the fuel accuracy ?
 
I have a different problem. The Garmin gauge has been stuck on 85.5 gallons for weeks. I have found that when the Yamaha gauge displays 2 bars there is about 40 gallons remaining in the tank so I have been going by that.

Any comments on the frozen Garmin fuel gauge? Thanks!
 
Is the Garmin yamaha page displaying fuel used and miles ? Is the Yamaha display showing this same info. If so, and you're not seeing the fuel remaining in tank, its likely a garmin software issue - call garmin. If it not displaying the fuel used, then again call garmin, but its likely a yamaha/ garmin communication issue.

The process is pretty simple for the Yamaha fuel injected engines. Every time an injector squints fuel, the Yamaha counts x fuel used. Those bytes should then be available to the Yamaha display and to the Garmin. The Garmin then calculates the fuel in tank, minus the fuel used. The issue is tracking down where the data is getting lost. Software is a wonderful thing.
 
I have a different problem. The Garmin gauge has been stuck on 85.5 gallons for weeks. I have found that when the Yamaha gauge displays 2 bars there is about 40 gallons remaining in the tank so I have been going by that.

Any comments on the frozen Garmin fuel gauge? Thanks!
Jcat2010 said:
Is the Garmin yamaha page displaying fuel used and miles ? Is the Yamaha display showing this same info. If so, and you're not seeing the fuel remaining in tank, its likely a garmin software issue - call garmin. If it not displaying the fuel used, then again call garmin, but its likely a yamaha/ garmin communication issue.

The process is pretty simple for the Yamaha fuel injected engines. Every time an injector squints fuel, the Yamaha counts x fuel used. Those bytes should then be available to the Yamaha display and to the Garmin. The Garmin then calculates the fuel in tank, minus the fuel used. The issue is tracking down where the data is getting lost. Software is a wonderful thing.
Click to expand...
Thanks for the tip. I’ll give it a look.
 
I have the 5000 series Garmin and Diesel Engine. Have found that it is very accurate when I fill, and go into "information-menu- and fill all tanks". Goes to 100 gallon on board. Have learned that Engine must to be running for this to work.
 
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