C10 Gauges - Fuel tank level discrepancies

[Markojo]

I ma new to the forum and Suzuki. I recently repowered with new 2018 DF250AP's. I have the C10 gages, 2 fuel tanks. When we first installed and powered up the network, the fuel levels read very accurately, showing pretty much exactly what the Yamaha gauge did before we swapped it and what i knew was in the tanks. I a couple fill ups in now and i have been noticing that the fuel tank levels are way off. They show full once i fill up and read fairly accurately, it seems, to about 3/4 tank. After that it is completely off, i.e. showing empty when there is 30-40 gallons left. The fuel usage reading is pretty good, but i feel that even there there is a 10 gallon discrepancy (and i have accounted for the unusable quantities in the tanks, I know to the gallon how much you can suck out of these tanks and how much will remain), for now i believe it shows that i have burned 10 gallons more than I actually have on 130 gallons. I will know for certain if this is that case when i do my next fill up.

I am not sure why it started inaccurately reading the tanks. At first i thought maybe a faulty sending unit, but when i saw the same discrepancy on both tanks. I ruled that out. Some considerations: When initially installed, the nmea network was isolated to Suzuki gauges and i had another one for the electronics. I have since joined the 2 networks as standalone they were both half baked, but I did place an isolator T between the Suzuki components and the other electronics, hence isolating the power sources. I have gone through the menus a couple dozen times looking for what i may have doe wrong or configured incorrectly and really cannot find an issue.

Also, is it possible to reset the total fuel used and not just the trip and seasonal? I have 2 tanks, so the main fuel level bar is constantly taking into consideration the total fuel capacity of 250 gallons, which i rarely carry, unless i am running offshore. i usually operate on 1 tank 70% of the time. I noticed it does reset itself when i set the fuel level to full, bit not when i add gas.

Many thanks in advance!
MJ

[Moonlighter]

Ok, this is something your dealer should have explained to you thoroughly.

Firstly, there are 2 ways that Suzuki C-10 gauges and networks can show fuel level, and they are totally separate.

Tank fuel senders method
If you have electrical fuel level senders on your fuel tanks, they can be linked to the network, and this will then show on the C-10 fuel gauges. I presume the Yamaha system is much the same.

Because you have two tanks you should have 2 tank level gauges. These work the same way as any old style tank level gauge - there is a float or similar in the tank that sends an electrical signal to the standard fuel gauge, but in this case they send it via the network to the C-10’s.

They need to be set up when first installed. The setup for twins involves 2 things - firstly, setting up the network so it knows which signal comes from which tank - therefore identifying each sender unit as port or starboard. When that is done, the recommended procedure is then to calibrate the gauges, starting from an empty tank, adding fuel in stages, until full, and setting the levels along the way.

The C-10 gauge manual tells you exactly how to do this, I believe. So, when you add fuel, the senders send signals to the gauges and the levels shown change accordingly.

The dealer should do the majority of this setup when installing the motors, but they may not be able to do the tank calibration without emptying the tanks and refilling them - this step is not mandatory but it is useful to do to make the tank levels as shown on the gauges more realistic. Of course, these levels are pretty rough anyway because they bounce around everywhere as the fuel sloshes around in the tanks.

The confusion often arises because the C-10’s can show fuel level from these senders, and also from the engine’s ecu as described in more detail below:


Fuel use derived from the engine’s ECU’s

The second and more accurate way to track fuel use is from the engine’s computers. The Suzukis calculate fuel used as they run.

This is why the question pops up on the gauges every time you start the engines - have you added fuel?

THIS IS TOTALLY SEPARATE FROM THE FUEL LEVEL SENSORS AS EXPLAINED IN POINT 1. When you fill up, the tank level senders DO NOT reset the Suzuki engine system to full.

This Suzuki system sends fuel related data to the C-10 gauges. Data sent from the engines is for fuel flow, fuel used and fuel remaining.

This system relies 100% on you telling it every time you fill the tanks to full (set to full), or just add fuel without filling all the way (a “partial fill”). Absolutely critical, or the fuel data reported will be wrong.

It is also why, when the system is first set up, someone needs to tell it how many engines are on the network, which one is which, how many fuel tanks you have and which engine they feed, and the tank capacities. Usually tis is done by the dealer, done via the network menu i n the C-10.

As fuel is used, the system then calculates fuel used and subtracts that from the tank capacity to give you fuel remaining. It can be displayed as a figure (recommended) or on a gauge/bar graph.

Each gauge or bar graph on the C-10 can be set to show levels from either the fluid level senders, or from the engines
In network language, we say that each gauge/graph can have a different “data source” set for it. In fact, every bit of info shown on the C-10’s has a specific data source set for it. This tells the gauge where to look for data to display in that position.

You can check which data source is set for a particular graph on the gauge by going into the data sources menu in the C-10. They can be changed, ugh some gauges have fixed data sources that cannot be changed.

This system is usually very accurate out of the box, but sometimes it is out a bit. The good news is that it can be fine tuned to make it very very close to 100% accurate.

BUT THERE IS ONLY 1 way to do this process, which is called calibrating.

This is how:

1. Fill both tanks to full, and in the fuel menu, reset both tanks to full.
2. Go fishing! Use a decent amount if fuel, I always recommend at least 1/4 of each tank, because the more you use, the more accurate the amount of fuel used will be.
3. Go back to the same gas station and preferably to the same pump, and fill each tank up to full again. Try to fill to the same “fullness” as you did last time. Write down the amount fir each tank.
4. Compare the amount of fuel the system says was used for each tank on the C-10 with what the bowser says. If it differs by more than 2 or 3%, then you should calibrate.
5. I havent done many dual engine calibrations but I think its the same as a single - when you refuel, select each engine separately and do the refuel process for each one. When you select “set to full” it will give you the option to calibrate, select yes, it them pops up a window where you input the actual amount added, do that, then finish the process. By doing this, you are changing the formula used by the system to calculate fuel use, its called the K Factor. Next time, the fuel use will be more accurate. If you repeat this process 3-4 times at most, then fuel use will be so close to 100% it doesnt matter!

This is the only way to calibrate fuel used to make it more accurate. You must fill tanks to full and do the process as described.

Now, There is one other RULE when using the refuel menu in the C-10. Here it is:

NEVER INPUT AN AMOUNT OF FUEL USED UNLESS YOU ARE DOING A PARTIAL FILL, OR CALIBRATING!

I see your comment that you dont often keep your tanks full. So that means that you are normally just adding x amount of fuel but not filling all the way to full. Now, once you have done the calibration process and got your system accurate, you can then safely start to do partial fills.

One last thing - if you reckon that maybe you have stuffed up the system accuracy by doing something wrong, then you can reset both engines fuel use calculations to factory (remember that K-Factor? This resets the K-Factor to factory settings).

To do this, turn both engine keys on, then in one of the C-10’s, open the system settings menu, then open the network menu/device list and select and open one of the Suzuki devices. There will be an option to reset fuel to factory there. Do one engine, then do the other one.


Hope this helps you understand how this system works and how to set it up and use it.

[Markojo]

Hi Moonlighter,

Thank you very much for the detialed reply and explanations on all the variables.

Honeslty, I am pretty much in tune with everything that you outlined, I am defintely clear on the 2 separate ways fuel is measured and have followed all steps accordingly, with one or two major excpetions in understanding and/or process. I did do complete full fills with calibration 3 times before doign a partial, wich was actually one tank full, the other empty. Details below.

- According to your expanation of how to correctly set all this up, it assumes running each engine off of its own tank (port/stbd). This is what I have NOT done and have never run the boat this way. My SOP is to run off of the main 70% of the time (both engines pulling from one tank) and when I run offshore, I fill up the aux and run off of it first and then switch to main. Ideally this is how I would like to continue to run the rig.

- Whan calibrating the tanks, I only did 2 point calibration (empty/full), as it was my understanding that using more than 2 points is typiically done for tanks that have odd shapes and are not rhombus'.

Many thanks once again!
MJ

[Moonlighter]

Ok thats good.

Given your SOP, I would probbaly have the network setup as 2engines/1 tank with the tank set up as the total capacity of both tanks.

[Markojo]

Thanks for that Moonlighter.

So you would not advise having them setup as 2 tanks, but both engines running off of 1 tank at time? The wyay i have it configured now, i did setup 2 engines and 2 tanks in the system. However on the fuel consumption page, there is one bar that shows me 1 bar the total of the 2 tanks or 250 gallons(130 Gallons + 120 Gallons). I assume there is no way to change this either to show consumption per tank? I have tried, but that page is one of the default Suzuki ones that cannot be modified and tried replicating it on a fresh page, but was not able to achieve 2 bars showing the respective consumptions of of each tank. Fuel level of course i did setup so I can see each tanks level feeding the signal from the digital fuel sender, which as i said is way off. For that, I will do the multi-point calibrations at next fill up and see if i can't get accurate readings on the fuel levels, but it's the consumption that I am more concerned with getting accurate and the levels are good to have as a cross reference.

Thanks again!

[Moonlighter]

I havent done a calibration with a boat setup as 2 engines/1tank - but that is actually how you are running things ATM. You have a main tank and a aux in effect. Both engines run of both tanks, I assume you have a tap to turn each tank on and off. So in reality ypu never know exactly how much fuel each engine has truly used.

When the boat setup is 2engines/2 tanks, the system requires tanks to be assigned to their respective engine. This way the system knows that engine 1 has used x amount from tank 1,and so on. Therefore you can calibrate with known and true quantities.

If this is how you have the setup until now, how did you go about the calibration process to date? Did you calibrate both interfaces, just one, and what did you input for actual fuel used?? An explanation of what you actually did would help a lot!

With a 2 engines/1 tank setup I am not sure how the system will respond to calibrating fuel.. But I am guessing the calibration will assume each engine is using half the fuel and then ask you to calibrate each interface using half the actual fuel used for each engine..... perhaps give this setup a try and see what happens and let us know?

[Markojo]

The way i set it up is as follows:

- 2 engines and 2 tanks - Vessel setup
- the 2 tanks are identified as port = main and stbd = aux (I obviously realized this was odd, but it was the only way to identify the tanks)
- each tank was individually calibrated 130 gallons for main/port and 120 gallons stbd/aux - System>Network>DeviceList>Fluid level sensors

The result of this is 1 bar on the page showing at total of 250 gallons.

When adding fuel, my first 3 refills were full fill ups, so i set both tanks individually to full. My last fill up was a partial (main/port was filled to full and stbd/aux was left empty) and i just entered the total amount I added, which went into 1 tank only, but the system obviously does not know which tank it went into absed on that manual input of fuel added (it does know which tank from the fluid sensor, but that has is independent of the fuel rate/burn/remaining) Regardless of this, the fluid sensor should still read the tank level accurately, which it does when it is full and remans accurate to about 3/4 tank as previously mentioned, after which the level reading starts getting whacky on me.

When you say "...and what did you input for actual fuel used?? ", do you mean input how much fuel was added? How do I input used? My understanding is that i only enter how much i added into the system, while the system tells me used. Am i missing something?

As I am typing this and revisiting my steps, it is becoming clearer that maybe the only way to properly do this is by assigning a tank to an engine and constantly running off of both. This really makes me wonder why it was designed like this. This would make complete sense for inboard vessels where you will generally have tanks placed port and stbd due tot space limitations and then naturally, for even weight distribution you would want to burn off of both tanks simultaneously. However, in outboard configurations, with 2 tanks, the tanks are generally centered on the boat and the logic of burning the fuel for weight distribution is different. I run best using the main, which is dead center on the boat under the helm. The aux, is located aft under the cockpit deck. Therefore, when i have both tanks full running long range, i want to get the aux burned off first because that extra weight there, plus bodies and ice generally in the cockpit all weigh her ass down.

[Moonlighter]

When you are calibrating an engine interface, what you are doing is getting the system to compare actual (from the gas pump) with what the system says was burnt by the engine.

So with a boat setup as 2 engines/2 tanks, the fuel used by the starboard engine (from the ecu) is compared with the actual amount of fuel taken to fill up the starboard tank at the pump. The system then amends the K-factor value for that engine interface.

Same process then repeated for the port engine.p/port tank.

So I was wondering, if you calibrated both interfaces, but filled only one tank, then how did you work out the figure to use to calibrate each engine....?

I gather that the normal setup for most monohull boats running twin engines is either 2 identical tanks, or one large tank.

With your SOP, that is why I think you would be best treating your main + aux tanks as a single tank, because you have no way to determine the true amount of fuel used by each engine when they both draw from both tanks. You would be better off just dividing the total fuel added to fill the tank/s to full by 2 - which assumes both engines burn the same amount. The resulting change to K-factor should give you accurate results overall.

I am still somewhat confused about what your problem is - if it is that the fuel tank level as shown by the fluid level sensor is wrong once the tank level drops below 3/4 , then that is totally unrelated to the calibration of the interfaces. It would only be solved by doing a multipoint calibration of the fluid level sensor.

Anyway, on the other issue regarding the calibration of the interfaces, I think the best course for you to chart a way forward is to talk either to your Suzuki dealer, or one of the larger dealers like International Marine, Outboard Specialties, or Brownspoint Suzuki, and ask them how they have done the boat setup in circumstances like yours, and then, with that setup, how to do the interface calibration (eg how to do a twin engine/1tank calibration.)

[Markojo]

Thanks again for the invaluable feedback!

Your question (So I was wondering, if you calibrated both interfaces, but filled only one tank, then how did you work out the figure to use to calibrate each engine....?), is puzzling me as well. When i was asked to enter the fuel added, there was no specification as to which tank it was added. In other words, the system did not ask me where to place the added fuel. That has to be because it is registering both tanks as one fuel load, as displayed by the bar on the fuel management page, though the vessel setup is set to 2 tanks, which registers correctly as 2 tanks in the fuel sensor options in respects to levels.

The other option I have been contemplating, is to set up the vessel as 1 tank registering only the main tank at 130 gallons. My thought process on this, is that i am pretty much mainly running off of that tank and i keep a reserve of approx. 25 gallons in the aux. which i keep for god forbid. The only time aux is filled is to run offshore, in which case i burn the whole quantity down while out there and switch to main right about when i need to start heading back. I dont know how the system will react to that with 130 gallons registered as the capacity and then i'm showing a burn of let's say 170 gallons without having inputted a gas fillup value. However, when i go the pump next time and fill the main and set to ful, the fuel used will reset back to zero anyway.

[knottybuoys]

Markojo/Moonlighter - as a slight aside have you been able to setup the tanks on the Suzuki gauges such that you have two vertical bars on the LMF 400. I know mine was configured like that (with 3 tanks) at some point but cannot seem to get back to it on the LMF only the SIMRADs.

[Moonlighter]

Thanks again for the invaluable feedback!

Your question (So I was wondering, if you calibrated both interfaces, but filled only one tank, then how did you work out the figure to use to calibrate each engine....?), is puzzling me as well. When i was asked to enter the fuel added, there was no specification as to which tank it was added. In other words, the system did not ask me where to place the added fuel. That has to be because it is registering both tanks as one fuel load, as displayed by the bar on the fuel management page, though the vessel setup is set to 2 tanks, which registers correctly as 2 tanks in the fuel sensor options in respects to levels.
K
The other option I have been contemplating, is to set up the vessel as 1 tank registering only the main tank at 130 gallons. My thought process on this, is that i am pretty much mainly running off of that tank and i keep a reserve of approx. 25 gallons in the aux. which i keep for god forbid. The only time aux is filled is to run offshore, in which case i burn the whole quantity down while out there and switch to main right about when i need to start heading back. I dont know how the system will react to that with 130 gallons registered as the capacity and then i'm showing a burn of let's say 170 gallons without having inputted a gas fillup value. However, when i go the pump next time and fill the main and set to ful, the fuel used will reset back to zero anyway.

There is no linkage whatsoever between the fluid level as detected by the tank level sender and the calculated fuel level from the ecu. None at all, so it has no influence on the refuel process whatsoever.

As I say, best to talk to a dealer who has done hundreds of twin engine installs and find out how they would approach the setup and calibration on a boat with main plus aux and twin engines.

[Markojo]

Moonlighter - Thanks again!

knottybuoys - That is one of the things I am questioning as well, as I am only seeing one vertical bar, though 2 tanks are configured and for the life of me i could not figure it out. I will post again once i have answers to my scenarios, which will hopefully include an answer to multiple vertical fuel bars.