Cummins/Smartdata fuel metering accuracy

[NorthernFocus]

I'd like to hear others' experience with the accuracy and repeatability of the fuel consumed indication by the Smartdata computer on the Cummins engines. Based on four re-fills, ours seems to read about 15 percent high(i.e. takes less fuel to fill than indicated was used) but does seem to be fairly consistent. I'm more concerned with the consistency than the absolute accuracy. What sort of experience have others had?

 

[sidetrack]

Consistantly inaccurate. It reads full for quite some time... and then drops 2o+ gallons. I have a few thousand hrs and its always been the same. Just make sure your fuel is always topped up.

 

[NorthernFocus]

I'm not referring to the tank capacity indication. I'm talking about the fuel burned as indicated in the trip log. The trip log shows hours, miles traveled, gallons burned, mpg, and average speed. That's the number I use. Agree the tank level/capacity indication is all over the place. Sometimes even shows me making fuel.

 

[sidetrack]

Sorry I misunderstood the original post. Fuel consumption and other noted features seem to be accurate in my estimation....

 

[Just Dreamin']

Dan, I also find the VesselView (Smartcraft) fuel used rate to be accurate as opposed to the fuel quantity display which on our tug magical. I have been running the same 69 gallons of diesel this entire summer. That is not an issue of VesselView or Cummins but the internal tanking sending unit which I do not wish to cut holes in the cabin floor to access. Just me. However, I did go one step further 4 years ago and installed the Mercruiser NEMA 2000 Gateway which brings all my engine information directly into the Garmin 5212. Once the Garmin is programed with your fuel information the corresponding fuel remaining display is very accurate and confirmed at fill up. You just have to remember to manually input the gallons added at each fueling, does not matter if you fill up or just add two gallons just input the information. I also do a minor adjustment to fuel remaining in my hard copy log if we use the gen set as the engine ECM (where your fuel burn rate comes from) does not know if the gen set is running. I am one of those that keeps a little notebook at the helm station where I jot down engine times and fuel data. Too many years in aircraft.
Mike

 

[NorthernFocus]

...I am one of those that keeps a little notebook at the helm station where I jot down engine times and fuel data. Too many years in aircraft.
Mike

That's not unique to flying. I've done the same my entire life on the water.

I just fueled up again and was again pretty consistent with actual fuel burned being about 15 percent less than indicated. Repeatable error on the conservative side works for me.

 

[knotflying]

I do not have the Cmmins, but I rely on the Garmin readout of fuel remaining and that is pretty darn accurate. As a former pilot I also use an average conservative fuel burn and time on the water as my backup in case all things fail.