SC 1000 Guages

[Oklahoma]

Serial number: 2B787722, 250 Pro XS

This boat came with the SC 1000 speedometer and tachometer.

Here is the manual for the gauges:
https://samerwebapp01apncus01.azuree.../8m0147197.pdf

On page 21, it describes how to calibrate fuel used. Questions.

1. This calibration is only for the fuel tank sending unit, correct? It has nothing to do with fuel flow described on page 12?

2. So, to calibrate fuel used, as described on page 21, you fill the tank full and input the gallons you added for the calibration. Question, if you just refueled the tank, how does the software determine what the gallons used was before you filled the tank? It has to have this value to do the calibration, correct?

Thanks for your help.

Ron

[EuropeanAM]

The instructions on Page-21 are a bit misleading. They are not actually calibrating the "fuel used"... they are adapting the fuel level data to more closely match the "highly accurate fuel used information".

That's what the multiplier is accomplishing.

[Oklahoma]

Don, thanks. Sorry to be dense but would appreciate a little more help.

1. When you say “the highly accurate fuel used information”, are you referring to fuel used on page 12? Does doing the fuel calibration on page 21 in any way calibrate the “the highly accurate fuel used information” you mention?

2. I believe you are telling me that it takes the gallons I enter and divides this by the “the highly accurate fuel used information” which gives a calibration factor. Then it uses this factor to modify the value from the fuel sending unit? Is this even close? If this is correct, I’m completely lost as to how they can calibrate the fuel sending unit when the fuel sending unit’s value isn’t part of the equation for the calibration factor.

Again, I wish you would have written the manual for these things!!! Thanks again.

[EuropeanAM]

Page 12 really doesn't have much about "fuel used"- it simply covers "Fuel FLOW" which is essentially an "instant" figure that changes with any number of factors or throttle settings.

You really should not need to utilize any "fuel used" calibration. Simply choose the "refilled" method.

The Calibration method, as stated on Page# 21 allows you to create a multiplier that runs against the fuel sending unit information: "The multiplier is used to fine‑tune the fuel gauge sender to correct for fuel used errors".

"Fuel Used" is a generic statement there- it's NOT referring to the PCM data that figures "Fuel Used" (or consumed) based on the Injector Pulsewidth data the PCM uses to make the engine run properly.

[MichaelJ3]

My suggestion is this:
0) Make sure your boat actually has the fuel harness connected to the outboard, if not, there is no fuel sender data available on SmartCraft network.
1) See if you have a normal rectangular, cube shaped tank...and find its capacity
2) If #1 is true, use the default Fuel Gauge Calibration (essentially linear on the fuel sender)
3) Set the tank capacity using the capacity from step 1.
3) Reset your "fuel used" screen to zero after every fill up
4) Use your "fuel gauge screen" (the one that shows % fuel remaining based on the tank sender) as an approximate view of how full the tank is
5) Use the "Fuel Used" Screen as the Bible. It takes the info from the ECU. I have found it to be accurate to within about 0.2 Gallons (meaning when I start with my 34 gallon tank full, go run the boat, and then return to the same gas station, I can usually add the same amount of fuel as shows up on the Fuel Used screen to within +/- 0.2 gallons...usually even closer than that).

Since the fuel sender is at one spot in the tank, and the boat changes pitch, roll, etc, the gauge is accurate as an approximation based on the current pitch and roll of the boat...but if you start with a fixed known amount in the tank, reset the fuel used on the gauge to zero, you know how much you burned...and how much you started with...so you know what is left...and it is pretty spot on. This Fuel Used is probably the single most valuable piece of info on a SmartCraft gauge system...in my opinion. Best part, there is one on the Tach and one on the Speedo, so you can choose one to be your per tank used, and maybe reset one at the beginning of each season to monitor your seasonal usage..its like an A and B trip odometer in a car.

[Oklahoma]

Don and Michael,

Thanks so much for continuing to educate me.

Don, I believe? the fuel flow screen mentioned on page 12 has an instant reading as well as a 'running total' (since last reset) values for fuel used? Is this the value that is calculated by the PCM?

As Michael stated, I have seen fuel used values available on both the tach and speedo gauges.

I think I almost understand. Would one of you please tell me which parameters are being used in the equation to calculate the multiplier on page 21 (the fuel used option)? For example, I refill the tank and it holds 20 gallons. So, the equation to determine the multiplier is 20/X. Where does X come from? Is it the running total of the fuel used as calculated by the PCM? If so, does it take this value from the tach or the speedo. As Michael stated, you can reset the fuel used values from each gauge independently.

Thanks so much for your help.
Ron

[EuropeanAM]

Yes- the actual INSTANT fuel "consumption" data, and the total fuel used (resettable) are based on the extremely accurate PCM fuel delivery information, contained in the MAP tables.

The information on Page-21 is not dealing with the above information at all. It is merely permitting you to "tweak" the volume settings that are determined by the fuel sending unit level X fuel tank capacity. Example: 100 gallon tank, with sending unit output for 1/2 tank, and NO multipler (ie: 1.0), equals 50 gallons of fuel remaining.

So that's (100 x .5) 1.0 = 50 gallons.

The red "1.0" is the only thing you can set there on Page-21 (for instance, let's say at 1/2 tank level you can only get 40 gallons into your 100 gallon tank, and feel confident that means there was really 60 gallons in it). In this case you could add a 1.2 multiplier so as to have that particular sending unit level register as being 60 gallons of fuel in the tank (rather than 50).

This method is seldom used, and the manual is pretty much clear as river-mud on this topic.

[MichaelJ3]

I would say one other thing to maybe help clear things up a bit (Don said it above, but maybe saying it differently will help).

The "Fuel Used" display on the SC-1000 Gauges (Both Speedo and Tach), is a running number of gallons consumed since it was last reset to zero, and is provided/calculated by the gauge and engine ECU using the programming Don mentions above. It is Highly Accurate, you can be sure it is giving you accurate info. I would bet my life on it...seriously, my experience with it is that good...

The "Fuel Used" calibration method mentioned on Page 21 is a way/strategy to calibrate the Gauges Full/Empty Fuel Gauge to work with the fuel sending unit (float) in the tank. It is perhaps an unfortunate coincidence that the writer of the gauge software and manual used the "Fuel Used" term for this calibration effort. A better term might have been "Fuel Replaced."

The info conveyed is letting you know that, after you set your tank's capacity to some value C (in preceding Tank Calibration Steps), When the float on the sender is all the way at the top, the Fuel Gauge on the SC-1000 will say you have C gallons (100% ) remaining.
Then you reset the gauges highly accurate Fuel Used meter to zero, to track your fuel burn.
Now, you run the boat for a time, and burn 10 Gallons of gas according to the Full/Empty Gauge: The SC-1000 Full/Empty gauge says you have C minus 10 Gallons remaining.
Then you fuel up, and you can only fit 8 gallons in...(you confirm your fuel burn by checking the aforementioned highly accurate Fuel Used screen, and in this example, lets say it agrees that the fuel burnt was 8 gallons).
This Tank Calibration Step described on Pg 21 allows you to tell the Full/Empty gauge that it had calculated remaining fuel in the tank wrong, and you should change the multiplier to 0.8 (8/10) to compensate.
Alternatively, you could skip the multiplier calculation and use the "Amount Refuled" screen instead and tell the gauge you just replaced 8 gallons of fuel instead of the 10 it calculated from the change in voltage on the tank sending unit.

Thus, these calibration steps allow the gauge to learn that some change in voltage from the full spot to where the float now is corresponds to 8 gallons used instead of 10 (C minus 8 gallons remaining). This might be useful in the case of a fuel tank that is not a regular shape (imagine a cone shaped tank where the top is wide and the bottom is narrow...so the float will travel further on the bottom of the tank than the top for the same volume of fuel and thus the float has a non-linear response with respect to gallons of fuel per change in float position).

Reality is, none of the fuel info from the Tank Sending Unit is used in any other gauge function except for showing the Gas Gague...and the low fuel alarm.
My experience is that all the fuel to waypoint, fuel used, gallons per hour, economy info is calculated using the highly accurate info from the ECM.

As an aside, if I had an irregular shaped tank, I think I would use the 3rd calibration method...which you haven't talked about yet, which is the "start with an empty tank and fill it in 1/4 capacity increments" method...which is yet another way to teach the gauge how much change in voltage corresponds to how many gallons (ie float position).

I will say it again though, if you have a regular shaped tank, and you know its capacity, my suggestion is set the Multiplier at 1.0, set the capacity, and don't mess w/ these calibrations...unless you notice vast differences between the fuel used as reported using the "Fuel Used" screen and the "Gas Gauge Full/Empty" screen, It is likely not worth the hassle. Because, even if you do, you can modulate the reading on the Full/Empty gas gauge by hitting the throttle and changing the pitch of the boat (which is why I think gas gauges in boats are nothing more than an approximate estimate of what remains, and I find this whole line of thought that the gauge can tell me "gallons remaining" from a float position to be hogwash).

You probably can get close to approximating the "Add gas in quarter tank" increments method by totally filling your tank, then running it until you have used most all of the fuel (use the Fuel Used Screen to get to maybe 1 or 2 gallons remaining).
Then execute the Fill by 1/4 tank calibration method and watch the pump to know when you have added 1/4, 1/2, 3/4, and Full amounts...your choice whether you do this on the water, or on the trailer. The reading accuracy will only be good when you replicate the pitch of the boat as you had it when calibrated.

[Oklahoma]

Don, thanks so much for sticking with me on this. I finally get it. If I want to calibrate the sending unit, I can just enter a multiplier.

I do have a curiosity question though... On the last box on page 21, it indicates that you can enter the fuel replaced and it will calculate the multiplier for you. So, using the numbers in your example, the calculation for the multiplier would be (100 - 40) / 50. The 100 would be stored in the gauge memory as the tank capacity. The 40 would be entered by the user as described in the last box on page 21. Where does the 50 come from? It would have been available from the sending unit before you filled the tank. However, the tank is now full...

If you are tired of messing with me, just skip this. You and Michael have already given me the information I needed. Thanks for that.

[Oklahoma]

Michael, I posted the last post before seeing your excellent, detailed post. Thanks for taking the time to write it. You understand way more about this than I ever will. If just noticed you have a Reata. My boat is a Reata 212LS. I assume it is a 'regular' shaped tank but I haven't seen it. It is 39 gallons and located under the rear seats.

Anyways, I think I will rely on the 'accurate fuel used' and look at the fuel gauge information more for fun like you instructed. You give excellent advice. Thank you.

[SilverFox579]

This method is seldom used, and the manual is pretty much clear as river-mud on this topic.

I looked at that when I installed my Mercmonitor years ago and never bothered with it. My analog gauge is "close enough" for what it is, if I want precise data, I reset and use fuel consumption data provided by PCM.

[MichaelJ3]

Michael, I posted the last post before seeing your excellent, detailed post. Thanks for taking the time to write it. You understand way more about this than I ever will. If just noticed you have a Reata. My boat is a Reata 212LS. I assume it is a 'regular' shaped tank but I haven't seen it. It is 39 gallons and located under the rear seats.

Anyways, I think I will rely on the 'accurate fuel used' and look at the fuel gauge information more for fun like you instructed. You give excellent advice. Thank you.

My guess is it is pretty close to a regular rectangular prism or cube...and thus a linear response of the fuel sender will be just fine and approximate what you want to know.
Get used to resetting Fuel Used, you will never look at the gas gauge screen again.

Happy to help, that is what we are here for.

[Oklahoma]

To further the confusion on this issue... Had a slow morning fishing and decided to play with the SC1000 gauges.

Both the speedometer and tachometer report a running total of fuel used since the last reset. This information is coming from the PCM. Also, both gauges allow you to calibrate the fuel used value being reported.

Here is the interesting part. If you change the calibration factor, the gauge modifies the running total of fuel used coming from the PCM! It does not modify the gallons remaining being displayed on the speedometer as the gauge documentation indicates. Not what I expected to find!

Not sure if all SC1000 gauges behave this way but mine do.

Again, thanks the help.

Ron

[EuropeanAM]

Interesting tidbit there, Ron.

I can honestly say that you are the FIRST I've had get into this particular area of those instruments and try to work with it.

[Oklahoma]

Don, if you happen to run across the guy that wrote the documentation for these gauges, would you please slap him for the both of us (assuming he isn’t too large of course)!

[moymurfs]

Don, as long as we are discussing the SC1000, have you had anyone request repair/replacement of a SC gauge under their Platinum service plan (they are listed as covered components)? Let's say for the dreaded LCD failure that results in a splotchy smear and when on, only half of the LCD window works.. just curious...

[EuropeanAM]

Yes, provided that they were subject to the Platinum Product Protection Plan (specific criteria applies).