Fuel Flow calibration

[WallabyBob]

I have a 2017 DF70ATX.
A simple setup with a digital multi function gauge.
It has a Garmin GPS antenna connected to the NMEA 2000, nothing else.
I use 24 litre portable tanks and swap the hose over when empty.
The fuel flow shows 20 litres used when I have actually used 24, ie the tank's empty.
This is accurate and consistent from new.
There are no senders or gauges.
Can I calibrate the fuel flow to show the correct amount with what I have or is it only a dealer/cable/special software situation?

[Moonlighter]

Which digital gauge do you have?

The Suzuki C-10 digital gauge has been supplied in the USA for several years, and only recently the Suzuki OEM MFG4 as its known has been introduced there. The C-10 fuel data can be calibrated.
,
The rest of the world has been getting the Suzuki MFG4 since 2015. It cannot be calibrated. By users, or by the dealer to the best of my knowledge.

I will take a punt that your WallabyBob tag indicates you’re also an Aussie, and live here too!

That being the case with a 2017 engine, it will be a MFG4, so best talk to your dealer in case something isn’t set up right, I understand that their accuracy is typically extremely good. Although i do understand they are largely plug n play with nothing much to set up that affects fuel data.

Have you verified that the portable tanks you use actually take 24 litres to refill again after the fuel runs out?

[WallabyBob]

IMG_1170.JPG
Thanks Moonlighter

Yes I'm in Western Australia
This is a photo of the gauge after pressing the menu button.
I fill the tanks at the bowser (pump), not always the same one, so I think the 24 litres is accurate.
It's consistent: 20 litres indicated = 24 litres real, just means I'm always doing maths.

[Moonlighter]

Yes thats the Suzuki MFG4.

Best talk to your dealer. Should not be that far out.

[WallabyBob]

I spoke to a Suzuki rep at the boat show at the weekend.
He said that fuel consumption is estimated using an algorithm that uses distance from the GPS
revs from the engine and makes assumptions about the type of boat and prop.
There is no actual measurement device
No adjustment is possible, just live with it

[Moonlighter]

That is what I expected. I knew there is no way users can calibrate, but was hoping for you that there might have been something in the setup that might have helped.

His explanation is kinda a crude laymans version. The actual calculation done by the system has nothing to do with “estimating” anything to do with the boat and prop - the engine’s ecu controls how much fuel is injected each time the injector is fired, and this takes into account a whole range of factors from numerous sensors in the engine. So boat weight, props etc are reflected in things like engine manifold pressures, exhaust temps and rpm, and it is those kinds of factors which influence how much fuel the ecu allows the injectors to inject into the cylinders.

So it is relatively straightforward for that data to be used to calculate fuel flow and from there to get the exact quantity of fuel used. Typically it is extremely accurate for all those reasons..

I have heard that dirty or faulty injectors can have an influence on fuel data accuracy.... if it really bugged you, I guess you could have the injectors flow tested, and or cleaned... can be expensive though.

I would be inclined to run some good quality fuel injector cleaner thru the next couple of tanks of fuel anyway. Check with your local dealer to ask which one they recommend.

Also, since you are running small portable tanks, do you have a good water separating fuel filter plumbed into the fuel line between the tank and the engine? You really should have, these engines really do not like dirty fuel.