Dynon Skyview EMS Fuel Quantity

[nigelspeedy]

My RV-8 has the stock vans float sensors hooked up to the Dynon Skyview EMS. To date they have been great. Coming back from Sun n Fun my right fuel quantity started acting up. Fill the tanks, and then start up and they both display full. Take off and in the climb out the right fuel quantity gage starts to slowly reduce from full down to zero over about 5 minutes. Its not leaking at all. When I start descent it starts to increase again. Land and shut down and open the tank cap and it is still full. Start up and it shows full again, but same deal in the climb it starts to drop all the way to zero.

Is it high resistance or low resistance that makes the tank show full?
What would be the effect or an open circuit or short?
Is there a common failure mode for the Vans float sensors?
What is the time 'filter' on the fuel quantity display?
Anyone else seen this behavior?
Any help troubleshooting would be much appreciated.

Cheers

Nigel

[dynonsupport]

Nigel,

If empty or full is high or low resistance matters which way the float is installed. The cool thing is you can figure this out from looking at your SkyView calibration. Go into HARDWARE CALIBRATION then EMS CAL then FUEL LEVEL CAL. In here, you can see what voltage equals what fuel level. So look at what voltage is 0 gallons.

SkyView "pulls up" the voltage and the float pulls it down. So if the 0 gallon voltage is lower than the 2 gallon voltage, then your sensor is reducing in resistance as fuel goes down, and vice versa. In the decreasing resistance mode, then a short to ground would represent zero. In the reverse case, an open wire would represent zero.

As for filters, SkyView supports 3 different "speeds" for fuel level senders. The standard one takes about 16 seconds to change 66%. So if you have 10 gallons, and suddenly go to zero, it will show 3 gallons after 16 seconds.

Don't forget to check your datalogs to see if they have any hints as to what is going on.

[nigelspeedy]

I re-crimped the ring terminal and made sure it was on good and tight and this seems to have solved the problem.

Lesson learnt: good connections and grounds are critical to good EMS operation.

Cheers

Nige

[Glas467]

Nigel,

Good susinct write-up -- always nice to have follow up when the problem is solved.

Dynon,

Many thanks for your always excellent support!