Fuel Tank Drama Continues…
October 22, 2021 – I have given up on my right tank fuel quantity issue, for now…
I got a new sensor from Van’s. I installed it, reinstalled the tank, ands started the fuel calibration again. Believe it or not, no help. The sensor and float move just fine, and electrically it works. but when it’s in the tank, there is still no apparent movement (i.e. voltage change) when I add fuel.
I tried bypassing my wiring; running a wire from pin 21 of the Dynon EMS to the sensor. That was no help. I also double-checked the ground.
OK. I’ve had enough. I decided to go scorched-earth, and reconfigure the tank back to the fixed pickup tube and relocate the float sensor to it’s normal place in the inboard bay of the tank.
I removed the tank again, and ordered the pickup tube with a screen and the anti-rotation brackets from Van’s.
I removed the access plate on the inboard rib, to see if I could tell if the float was hanging up. I was able to stick something through and move the float. I also checked the resistance while I was moving it. I couldn’t find anything wrong.
I cut an access hole in the back baffle of the tank as needed to get access to the bay.
Here’s the flop tube inside the tank.
I removed the flop tube and the float from the next bay over. I left the small mods that are installed with the flop tube; there’s a twisted strap that keeps the flop tube from hanging up in the next rib, and there’s a small trap door that acts as a check valve to keep fuel in the inboard bay so fuel doesn’t slosh outboard and starve the flop tube.
I drilled the hole in the inboard access plate for the sensor…
…and when I got the pickup tube, I located that hole, then secured the tube in place along with the anti-rotation bracket.
So here’s everything in place:
The float does not and cannot hang on anything. It also doesn’t touch either the top or the bottom.
I made the panels to close the tank back up and installed them.
Two days later, I pumped up the tank with a bike pump and used soapy water to look for leaks. Absolutely nothing…
I plugged the hole at the leading edge where the flop tube was mounted, and where fuel exited the tank. I used an AN fitting with two AN caps and thoroughly sealed them inside and out…
I also had to make a new fuel line to the fuselage since the location was different…
I installed the tank, and proceeded to begin the calibration.
Guess what?… It still doesn’t work.
Well, I was able to get a “calibration”, but I had to thump the top of the tank with my fist to get the sensor voltage to change after each 2-gallon addition.
I filled it to 21 gallons, and the Dynon accepted the calibration.
I proceeded to drain 10 gallons from the tank to put in the left tank. The indicated quantity did not change.
My drain valve was dripping, so I drained the rest of the fuel so I could check the o-ring on the drain. I did expect to find a piece of aluminum stuck there, and I did. I reinstalled the drain. With an empty tank, Dynon still indicated 20+.
OK. This airplane needs to be flown, so I decided I’ll not hit my head against the wall any more, and just manage the fuel for the time being.
I may call Van’s at some point, and probably will end up ordering another sensor, but maybe not until the condition inspection next year.