Standard Horizon FF41 Fuel Flow Calibration

[Bill]

Hey folks, after a frustrating day of failing (either by phone or e-mail) to get some clarification from the company regarding its manual's directions on calibrating the FF41, I'm hoping someone here has some real experience.

According to the manual, the first step in calibration is to reset the total log value to zero. You are then supposed to note the actual amount of fuel used and compare that to the amount shown by the total log (and then adjust based on the difference). But wait a minute, step one said to zero out the total log.

The directions then said to hold down the flow button during power up, and the meter will show the current total log value (and it is then that you use the up down buttons to bring that amount into agreement with the actual amount used). Well, I tried that - followed the directions - and instead of getting a display of the total log amount, I got zero. Duh. Not too surprising, since step one told me to zero out the total log amount.

Seems like there is a missing step or the steps are out of order, or something. The company couldn't (or wouldn't) give me any direction, can another FF41 owner give me some help?

Many thanks,

Bill
Shark Shadow
'88 22' XF

[Capt. Bob]

Don't own one but I read the directions.

Calibration
The fuel transducer supplied with the fuel flow
meter will provide readings at better than 5%
accuracy. Individual calibration will increase this
level of accuracy to better than 2% over a fuel
flow range of 2 to 32 US gallons per hour. Use
the following steps to calibrate your fuel flow
meter:
1. Reset the total log value to zero (see
previous page).
2. Use a known amount of fuel. The larger the
amount the more accurate the calibration
will be.
3. Take note of the actual volume of fuel used
and the fuel used indicated by the total log.
If these two totals are different the
instrument may require calibration.
4. Press and hold the
key while applying
power
FLOW TOTAL


Hold down during power up
5. Release the
key. Display will flash
current total log value.

6. Use the
or  keys to make the display
indicate the actual volume of fuel used.
7. Press both keys simultaneously for 1 sec
to exit.
FLOW TOTAL


Press and hold for 1 second
The fuel flow meter is now calibrated.

So.......

Zero out the log as per the directions.

Burn a known amount of fuel: The best way I know is to fill the tank and go for a ride. Refill when you get back and use the difference as your measured amount.

Compare the amount shown on the gauge with the amount shown at the pump. (I'm guessing this is where the confusion lies. You need to get a reading on the gauge for a comparison by running fuel through it and comparing "gauge measured" to "actual used".) Again, I'm guessing you haven't done this step.

Adjust the gauge amount as described to match the pump gauge amount and set by holding down the two buttons described.
I would suggest you do this as many times as it takes to reach a comfort level you can live with while underway.

I have a Flow Scan and the basic idea is the same except you calibrate the gauge by manually setting a series of numbers on the back of the gauge itself. The Flow Scan I have resets when the power is turned off to the unit. Analog gauge with digital totalizer. Very Old School and Scary Accurate.

Good luck.

Edit:
Now that I think about it, it sounds like you reset the gauge after you ran the boat. That would explain why you don't see a total amount. Again, just a guess.

[Bill]

Capt. Bob,

Thanks for the quick reply. Those are the directions in the manual, alright, and I (think) I followed them to the letter. The problem is that having reset the total log to zero in step one, when I held the flow key down while powering up in step 4, the resulting display read zero rather than what it had been before I zeroed it out at the beginning.

I know the amount of fuel  the meter said I used (total log, before resetting to zero) and the amount I actually used (three trips to the gas station to refill). I haven't run the boat --- I just reset the total log to zero, as per step one. But then the meter read zero instead of the pre-zero total log amount when it was time to calibrate via the up-down buttons.

The only thing I can think of is that I should have called up the total log value AND calibrated via the up-down buttons BEFORE resetting the total log to zero. But that isn't what the directions said to do. So, I'm stumped.

But, thanks again for trying to help.

Bill
Shark Shadow
'88 22' XF

[Capt. Bob]

The only thing I can think of is that I should have called up the total log value AND calibrated via the up-down buttons BEFORE resetting the total log to zero.

You hit it on the head Bill.

It would appear you need to start over (good reason to run the boat ) and use that method. I'm betting you will be able to calibrate.

Clear the data.
Run the boat.
Then call up the data and calibrate. You only need to zero out at the start of the trip for calibration.

Good luck.

[RickK]

You only need to zero out at the start of the trip for calibration.

I'm thinking you only have to do it once and then calibrate from there - don't zero it out again.

[seabob4]

You only need to zero out at the start of the trip for calibration.

I'm thinking you only have to do it once and then calibrate from there - don't zero it out again.

Agree with Rick here.  Zuke's SMIS gauges (Lowrance LMF-400s) call for an initial zeroing, that's the last time you do it.  Then, from there, the initial trip will get you reasonably close.  From there, you go through some additional operations (sorry, can't remember), and it gets you REAL close with each trip...

[Bill]

Capt. Bob / Rick,

O.K., we have a consensus! I'll zero out the total log, then run the boat, and then calibrate from that point as per the rest of the directions. But, as an old guy increasingly susceptible to cold weather, I'm going to wait until later in the week (when the temps are supposed to warm up a bit here in the Tampa area) to take the boat out and be able to burn a fair amount of gas without freezing to death.

Thanks again for the help, guys; I'll report back when I have the results.

Bill
Shark Shadow
'88 22' XF

[Capt. Bob]

Sounds good Bill.
As I stated earlier, I would consider doing these steps several times to gain a warm and fuzzy feeling with the gauge. After that, when you feel comfortable, you can stop resetting the total and allow it to accumulate your usage over time.

Myself, I would feel better if I checked the first time, re-calibrated, then checked a second(and third, fourth,fifth)time to see that the gauge was reading true (and tweaking each time, if necessary). That way, you get the calibration as good as the instrument allows (as SB stated with the Suzuki/Lowrance gauge) and at the same time, build your confidence level in trusting the gauge.

Good luck and post up what you get,

[Bill]

Finally got out on Friday - a little breezy, but a beautiful day on Tampa Bay. I ran from the Southshore over to the main shipping channel just east of St. Pete, and back. Ran at about 4000 rpm doing about 25mph into the wind, and about 27+ back --- in other words, I gave the old Johnson an excuse to burn some fuel (not that it needs an excuse, of course).  The flow meter showed 8 gals used; actual used amount was just over 11 gals. As we discussed, I calibrated the flow gauge based on modifying its total used without first zeroing this out (as called for in the directions). Sure enough, this time it worked and I completed the calibration. I am left with the question of whether I can/should now zero out the "total used" in order to lay the basis for another calibration after the next trip (as you all noted, I'll probably need to do this 2-3 more times). Logic tells me that the corrected/calibrated total having been "accepted" by the meter computer, zeroing out now should be fine. (But initial zeroing out according to the directions didn't work out so well. so we'll see.) Still, thanks to the comments and observations you folks provided, it looks like I've at least got the basic calibration process correct now.

Thanks for the help,

Bill
"Shark Shadow"
'88 22' XF

[John Jones]

Since you adjusted it, I would zero it out before the next trip.  Flow calibrations like this are the most accurate over a long term with a lot more fuel burned but your intentions of doing it in several small steps will work out just fine.  If you don't zero it after adjusting, then next time you will not really know how much to adjust.  Each trip should get it tighter.  If you were to make several trips and burn a significant amount of fuel without adjusting and without adding fuel, then fill and calibrate it will get you pretty dang close.  One long trip using say 1/2 tank or more will get you there too.