Fuel Capacitors Started

Time: 2 Hours

I spent most of the day working on my sons car. It needed new rotors, brakes and calipers for it to be safe for him to drive. I’m not much of an auto mechanic so it was a big job for me. So that took up most of the day but I was still able to get so work done on the RV after I scrubbed the Hangar clean from all the brake work. So you learn early that you put parts together and take them apart and put them back together. I had to take the tanks all apart so that I can do more work on the ribs.


20140125-223917.jpgThe next step is to work on the fuel quantity sending parts. You have 2 options to chose from, the first is a float system that uses a plastic float that rises and lowers with the level of fuel. The float system is proven but also has moving parts and has the potential for failure. The second is a capacitive fuel sender. There are a couple of benefits to this design, no moving parts and very it’s sensitive to the amount of fuel and can read the quantity very accurately. I chose to go with the capacitive senders for the accuracy that if provides. The design is based off of two individual plates in the tank that have a small electrical current and are separated by a dielectric(insulator) in this case the fuel. The capacitance between these plates and the fuel is measured giving a fuel level. The first steps is to position the 2 plates per tank on their ribs per the plans.

20140125-225958.jpgI then matched drilled the 3 holes with a #20 bit on one rib. I then used that rib as a guide for the opposite end rib of the other tank.  That rib was then used as a guide for the second rib on the first tank and finally it was used for the final rib of the second rib, clear as mud?  The fact that the ribs are the same part number in both tanks allowed for me to place the ribs back to back and match up the tooling holes.  These parts are pretty accurate so using the match drilling this way made the holes come out perfectly.

20140125-230328.jpgThe plates are mounted on opposite sides of their ribs when viewed form
Inboard to outboard. So I laid them out as they would sit on the ribs so that I could mark them for the nutplates that they get.


20140125-230611.jpgI then treated all the edges and debured the holes so that I could rivet the nutplates. That was a pretty quick process with the squeezer. I decided to call it a night and clean up but before I did I mocked up one plate to see how it looked. The plates need to be isolated from all other metal, the rib, and have plastic spacers that take care of this.


20140125-231014.jpgI will get back at it tomorrow and make more progress on the tanks.

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