Garmin GMI20 Guage Fuel accuracy

[zan0_15]

Gday all,

Hope you all had a crackin Australia Day!

I'm after people's experience with these gauges particularly with how accurate they have found the fuel consumption to be?
Last couple of trips I have noticed a difference between what my gauges say I used last trip and what I am actually putting in at the bowser. Last trip the difference was 15 litres more put in than what the Guage was telling me I had used.
I feel that is a fairly significant difference and believe it should be more accurate than that. I may be wrong....

Keen to hear from anyone who has had any experience with them.

Cheers,
Zane.

[Jsmfun]

Yea mate I have a Suzuki df175 with gmi 20 and a 751xs and 70dv
i had the same problem and it even caused me to run out of fuel nine miles of the goldy

you need to do a update and also mainly rely on your main head unit as it seams to freeze when traveling.
mine I noticed froze once from mud island to the cape I think it was about 25-30l when I came of the plane it stayed at 4200 rpm and I had to turn the power of to reset it....

now on I only insert the fuel into the 751 and it is always accurate and the gmi20 is out 3-10l every trip
cheers Scott. I hope this helps

[Dogtoooth]

Gday all,

Hope you all had a crackin Australia Day!

I'm after people's experience with these gauges particularly with how accurate they have found the fuel consumption to be?
Last couple of trips I have noticed a difference between what my gauges say I used last trip and what I am actually putting in at the bowser. Last trip the difference was 15 litres more put in than what the Guage was telling me I had used.
I feel that is a fairly significant difference and believe it should be more accurate than that. I may be wrong....

Keen to hear from anyone who has had any experience with them.

Cheers,
Zane.

I witnessed my GMI 20's freeze up on me heading offshore once. I slowed down to idle and turned the ignition off. I restarted the outboard and she lit up normal again. I googled them on a USA forum and they can have to habit of freezing up while driving. They have software issues with them. I have put the latest software update since then through my Garmin gpsmap 751 via NMEA 2000 from my Garmin dealer and all seems good so far.

[scottar]

From comments above, there sounds like there is a software issue that effects accuracy due to the unit "locking up". If the software fixes this all good. The other thing that could affect accuracy is the engine probe itself. The suzuki interfaces certainly used to have to be programmed to suit a particular model motor. As well as this there was also the facility to calibrate the fuel figures via a lowrance head unit. Whether this is still the case I do not know but it certainly made a difference in the early days of suzuki nmea2000.

[honda900]

Yes, the lowrance head unit is still required to set the calibration value that Scottar mentions.

Regards
Honda.

[Moonlighter]

Guys, I have done a lot of research and have lots of practical exprience on the Suzuki NMEA 2000 networks.

Firstly, the Suzuki interface cable automatically detects the engine year and hp it is connected to and has done for several years now.

No configuring of the interface is required any more, Scottar.

But yes, the intface can be calibrated using SUZUKI or Navico head units to improve fuel use accuracy, if necessary.

One thing many people dont know is that the Suzuki interface has a inbuilt storage/memory module, kind of like flash memory, that holds all the fuel used and related data. When used with Lowrance or Suzuki engine data displays or MFD's, those displays automatically select the Suzuki interface as the network data source for all fuel related info. They don't have their own on-board fuel data storage module. So the system works nicely.

Now, the Garmin displays add a complexity to the network. You see, the Garmin displays, unlike most Lowrance/Simrad, have their own on-board fuel data storage module. So when they get put onto a Suzuki network, they auto-select their own internal fuel data memory as the source of fuel data. What does this mean? It means that the fuel used/remaining information that is displayed on the Garmin screen is sourced from the Garmin itself, not from the Suzuki interface..... Plus, the network now has potential data conflicts due to 2 different sources for the same data.

My theory is this: the GMI-20 has a known fault where it quietly freezes and thus fails to calculate and record fuel useage. Therefore the actual fuel used and the preducted fuel used from the Garmin display do not match and the Garmin therefore significantly under-reports the amount used.

My suggested solution for those with Garmin GMI displays is to go into the Garmin displays network menu and find the network data sources menu. Find the current data source for all the fuel data items that you use, and change them from the Garmin (itself) and reset them to source their data from the Suzuki interface. The Garmin manual will tell you how to select data sources, i know how to do it on Lowrance or Simrad but am not that familiar with the procedure on Garmin displays, but it definitely will be there.

By using this approach, i believe that it wont matter if the GMI freezes - when it comes back on, it will look for fuel data from the Suzuki interface and this WILL be accurate because the interface is always is working whenever the engine is turned on and the network is powered. So, it will display the fuel used and remaining data that it finds from the interface.

Bingo, accurate fuel data displayed at all times! (Subject only to the possible need to calibrate the interface if it is a bit out)

Anyone like to volunteer to give this proposed solution a try? I am pretty confident that it will work. And i cant see any downside or problem that trying it might cause. But we will only know for sure if this is tested in the field.

[zan0_15]

Hey Moonlighter,

Thanks for the post mate. I am happy to give it a try as it cant be any worse than what it is now. No point even having the gauges at the moment, good for nothing. So when this wind finally settles down I will have a go and see what happens.

[Moonlighter]

I was also talking to my local Suzuki guy the other day and he tells me that they have finally pinned down a problem with the GMI gauges that causes them to be about 8% out in their fuel calculations, and that garmin is now aware of this and is supposed to be working in a software update to deal with it. It should solve the under-reporing issue.

Meanwhile, it would be good to hear how zan0 goes with the proposed solution i suggested above.