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Stalldog

Well Known Member
I bent my sender wire for left tank using the approx 3 inches on the plans, but I'm not happy with the range I'm seeing on the float. I searched and found a post saying it should be more like 3-1/4 inches per arm, so I would like to make another. Does anyone know what wire I can use to make this from? Anything special about it? Just plain steel wire of the proper diameter?
 
Never Mind

Never mind, I didn't realize I could order these from Van's for $5 each. Easier than finding a local replacement and trying to make the float bend.
 
Our senders hit the top of the tank at about 16 gallons per side. It appears to me that the placement of the sender at the root end will always max out before the tank is full. That being said when we finally got the red cube dialed in we are repeatedly accurate (pessimistic) by one gallon out of 35 every fill up. Of note each of the floats is optimistic ( says we have more fuel than we have) by one gallon a side.
 
While you're waiting on the replacements, get some coathangar wire and practice until you have what you want.

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You should be able to get the float to travel from bottom skin to top skin. Worked on my Panther tanks.

Tony
 
Thanks for the Info

Thanks, fellas, good info. I realize they will never be right on, but I'd like to get them mechanically correct as much as possible. I hate worthless fuel gauges. I've got a HD motorcycle that stays full until the tank is half empty, then falls like a rock after that -- worthless.

It does make sense that these will max out before the tank is full since they are at the wing root -- hadn't thought of that.

I'm surprised the plans aren't more exact in this area since the dimensions of the tank are locked in by match drilling, i.e. everything is set. Why just "approx. 3 inches?" I'll practice with coat hangers to find the right lengths.
 
you will find a replacement in the RV section of your closet. coat hanger wire works fine.

you may have to check a few, some are bigger diameter than others.

put a socket the right size in a vise to bend around to form the ring.

bob burns

rv-4
 
Too late, already ordered a couple from the mothership. Besides, that would be WAY too easy. If I don't spend $$$ and wait a week for a part, it just don't count! :D I figure it's got to be aircraft grade coat hanger wire anyway! ;)
 
Fuel sender float....where?

OK...so is my thinking right, in that I want the float to hit the bottom or top of the tank before it reaches it's full throw on the rheostat? I don't have any avionics yet, but I assume I can calibrate FULL and EMPTY on an EFIS later.:confused:
 
Above is correct. All of the electronic EFIS or EIS systems let you calibrate the fuel floats. Note that full will be less than full, as noted above due to the float hitting the top and the wing dihedral. (In my 10, "full" is 25 gallons even though the tank holds 30. Gauge will not move between 25 and 30).
 
So what have other quickbuilders been doing since the baffle is already installed? I ask because I just received my senders last week and was planning on putting them in this week. Should I just bend them to 3 1/4 and hope for the best, or is there a way to still get it right without actually being able to see it?
 
Seeing inside the fuel tank

I was struggling to adjust my RV-8 fuel sender floats; I screwed on the sender unit, but left the fuel pickup fitting off the access plate so I could look inside through that hole. After loosely attaching the plate to the fuel tank, I attempted to pry one side open to shine a flashlight inside while pressing my eyeball up to the hole, while simultaneously pushing the float back and forth with a long stick. I ultimately came up with a BRILLIANT (pun intended ) solution; I dropped a small LED flashlight into the fuel tank, thereby lighting up the inside, so I now could easily see the float through the hole.
I also found that if you use the float/wire configuation EXACTLY as depicted in the plans, the Right-side float will hit an interior stiffener; so I had to pop the float off the wire and reverse it's orientation. :D
 
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On my RV9-A QB wings, I tied threads onto the float wire and ran one thread out through the upper screw hole on the sender mounting plate and the other in the lower screw hole or the drain hole (can?t remember which). I cleco?ed the plate to the tank and then used the threads to pull the float through its range while measuring the senders resistance. I adjusted the bend until the resistance either reached minimum or maximum (can?t remember) just when the float hit the bottom of the tank. Took a while but was able to get it adjusted properly. I also found that the float would sometimes hit a stiffener and even jamb on one of the wings until I reversed its orientation as did AAflyer. If you are using an EMS that you calibrate, it probably isn?t too important that the sender be adjusted to its max or minimum just as it hits the bottom of the tank but if you are using analogue gauges that are not easily adjusted, it is probably more important.
 
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