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mlwynn

Well Known Member
Hi all,

I calibrated my fuel tanks yesterday. Briefly: RV8, GRT EIS 4000, Hx EFIS. Using the standard Van's float indicators, I got my first movement at 1.5 gallons and the floats stopped moving at 17 gallons. I used the calculations to set the SF and Aux off and got a pretty good representation.

If I set up the EFIS to show the 21 gallon capacity of the fuel tanks, then 17 gallons to full fuel shows about 3/4 tanks on the bar representation. If I change the capacity in the EFIS to 17 gallons, then it shows full but that is not really the capacity and I am not sure how that will work with the fuel flow calculations.

Is this pretty typcial for the float range for others? What do you think is the best way to set this up in the EFIS?

Regards,
Michael Wynn
RV8 (almost) Finished
KLVK
 
Because of the dihedral, the gauges will not show the top 3-4 gallons. If you calibrate the gauge properly, the gauge will show full until the floats come off the top of the tank.
 
I am not familiar with that EFIS, but I suspect you have the ability to manually calibrate the display against your ohm readings or other method. You definitely need your fuel capacity to be 21 gallons or your totalizer will never be correct.
 
I have set up mine in such way that reads 21 gallon when full. I start seeing movement in it when it gets below 18G and I suspect when it reads empty (zero gallon) I will have 3G left in the tank. But I also have my fuel meter that I reset at each fill up. The fuel meter has been very accurate (within .3G) so I use both of them in conjunction to know what is the total of fuel I have and how much in each tank.
 
It makes sense to have the 21 gallons as the capacity. How did you set it up to read 21 gallons full and then start registering below 18?

Michael Wynn
RV 8 Finishing
San Ramon, CA
 
Mike, if you really want that, then do this: suppose your calibration numbers were 15 gal= 3 volts, 17 gal= 4.5 volts, 18gal=5 volts, 21 gal= 5 volts.
In the HX calibration table change the third entry to 18gal=4.9 volts. This will give you the desired result.
However, I disagree with everyone else. I think the fuel gauge shoud 'fail' on the safe side. If set up this way it will show 21 when you have less fuel, say 19 gal. I just set the top limit to 18 gal. Then, if I have 21, the gauge is wrong but I have more, not less, gas then it shows
The fuel flow totalizer can be set up completely independent of the gauges.
 
BOb is correct. If the totalizer and the gauges are indeed separate, you do not want your gauges reading anything but the lowest amount of fuel still in the tanks when the float starts falling.
In my 6, they read 13 or so gallons each. When I fill up, I plug 36 gallons into the totalizer. When I first fire off I always check my totalizer for gallons remaining. The fuel guages are there for a physical cross check.
 
Fuel Level Reading

If it is not going to affect the totalizer, then I guess the safe thing is to have it read 17 gallons when full (at 21) and wait for the first four gallons to burn off. I will then have an accurate reading between seventeen and 1.5.

Thanks. This is good wisdom.

Michael Wynn
RV 8 Finsihing
San Ramon, CA
2014 Dues Paid
 
In my case, I use my totalizer as my first and actual fuel in both tanks first. The float type gauge is simply too inaccurate to narrow it down to a gallon or two or even three therefore I use it to keep the totalizer honest ( i.e. if it is reading low but my totalizer disagrees then I know something is wrong and to be checked).
I believe it reads 19 when full and starts moving when I have burned 2-3G roughly. Also my float will read zero gallon when I have about 3G left in the tank so that is another safety mechanism that I use beside to keep a mental note and time since filled up the tanks.
 
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