D

Dan J

I'm New Here
I am having difficulty getting enough signal strength/differentiation in the resisatnce coming from my standard resistance fuel float sensors in my fuel tanks for my Dynon 180 EFIS to do a good job calibrating the fuel level of my tanks. In talking to Dynon they said that it would be best to install capacitive sensors - good luck with that once all is assembeled!!!

Has anyone else out there encountered this problem? Any fixes that I can try?

One final option is to find a builder to trade my completed tanks for their parts with so I can build with capacitive sensors as origional equipment. It would save a builder one of the more gruesome assemblies - tanks I have never leaked and work great otherwise.

Thanks
Dan
 
floats

Actually i just calibrated mine a week ago and it went very easily.I did no tests other than ensuring the floats were in properly until I finished the plane and added fuel. The Dynon skyview is simple as can be, tell the puter the tanks empty, wait. When it tells you add 2 gallons, let it read the float, add another 2 gallons, let it read the voltage etc. Seems to have worked great with both sides no issues at all. I was pleasantly surprised how well the floats worked with the dynon.
 
Float arm rheostat is 'sticky'

The signal is just a resistance value and works fine... the float arm acts as a lever to the rheostat and there is quite a lot of drag at the base where the mechanical / electrical contacts are. In flight there is enough vibration that they move freely but on the ground the arm can stick with small fuel level changes... just tap the sensor a few times with each measurement to make sure that the float is at the new fill level.
 
[email protected] said:
... just tap the sensor a few times with each measurement to make sure that the float is at the new fill level.
Click to expand...

Not sure how one would do that, but maybe having a friend shake the wing a bit after each addition of fuel might ensure that the float isn't stuck while you sit in the cockpit and push buttons. Just a thought. I didn't have any troubles calibrating mine either.
 
Dan:

This shouldn't be a problem. I'm curious if there is something unique about your installation. Swapping out tanks to solve this issue is overkill, IMHO. The floats work perfectly fine and if I were building another plane I would do the floats again.

Have you considered that maybe you have a grounding problem? You probably already know this, but the sender mounting plate must be properly grounded to the tank/airframe. Try running a ground wire from the mounting plate to a solid place on the airframe and see if your results are improved. A permanent solution could be to manually ground the plates back to your common ground block (you do have one, right?).

Have you tried putting your multimeter on it? Your meter should tell you if you have continuity from the mounting plate to the airframe.
 
Oh yeah, one other thing. You didn't overtighten the mounting screw on the sender, did you? If you did, it's quite possible that the sender is broken. Ask me how I know.
 
Move the sender unit up and down while measuring resistance.
You should get about 30 Ohm to about 240 Ohm.
Works like a charm. If they do not change while adding fuel, you have done something wrong, like broken it by accident or not bending the wire nicely where it clips into the sender, or .......
Have played in this movie before :eek:
 
Great suggestions - now have the cure!

I really appreciate the great responses, the most likely cure suggested was to run a clean ground wire from ea float sensor mtg plate back to the firewall - this made all the difference! I guess I used so much black death tank sealant on all the joints when building the tanks there was little hope for a conductive path to ground thru the airframe. Thanks again. This was my first attempt at this means of getting suggestions/help and ended up being a great cure for what ailed me. Dan J
 
Don, you only need a short wire from the tank to the ELT barcket. No need to go to the firewall.
 
You must log in or register to reply here.