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Fuel Level Sender Open Circuit at One End

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iamtheari

Well Known Member
We are working on the fuel tanks and I ran into a possible issue. I wanted to run it by the board before moving forward.

I measured the ohm range on both fuel senders that I received with the RV-14 wing kit. One of them was as expected, basically from 25 ohms to 250 ohms, physical stop to stop. The other one read roughly the same through its range, but at the high end it went off-scale at the physical stop. I think it's an open circuit but it's also possible that the resistance is higher than my meter registers.

Should I replace the sender?
 
Sounds like you?re measuring them in open air out of the tank? If so, you can physically see the resistor coil and the wiper. This should give you a clue.
When installed, typically the float will hit the top of the tank before it reaches the end of the resistor coil. My guess is you have nothing to worry about.
 
JonJay said:
Sounds like you?re measuring them in open air out of the tank? If so, you can physically see the resistor coil and the wiper. This should give you a clue.
When installed, typically the float will hit the top of the tank before it reaches the end of the resistor coil. My guess is you have nothing to worry about.
Click to expand...

Correct, I am measuring on the bench out of the tank. I didn't see anything obviously wrong with the wiper or coil but I'll take a closer look tonight.

The instructions do say that there should be a 1/16 gap from both top and bottom tank skins when the sender reaches its travel limits. If I allow the float to touch the top skin before reaching end of travel on the sender, then the problem area on the sender will not be a factor. But then I'm deviating from the plans slightly in a place where electricity and gasoline vapor are mixed so I want to be careful. :)
 
iamtheari said:
Correct, I am measuring on the bench out of the tank. I didn't see anything obviously wrong with the wiper or coil but I'll take a closer look tonight.

The instructions do say that there should be a 1/16 gap from both top and bottom tank skins when the sender reaches its travel limits. If I allow the float to touch the top skin before reaching end of travel on the sender,
Click to expand...

Interesting. Not sure that would that would even be possible in the older kits. (Scott could enlighten us)
By all means, follow the plans. The last thing you want to do is get it installed and have to tear it out.
Kudos to you for checking it in advance!
 
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JonJay said:
Interesting. Not sure that would that would even be possible in the older kits. (Scott could enlighten us)
By all means, follow the plans. The last thing you want to do is get it installed and have to tear it out.
Kudos to you for checking it in advance!
Click to expand...
I haven't compared the plans for other kits. I know they use the same sender. So if it is safe to let it contact the top tank skin in an RV-6, why wouldn't it be in an RV-14? I'll hope for more information but I don't think I'll lose sleep over it at this point even if nobody chimes in before I rivet the baffle on the aft side of the tank. :)
 
It would probably work okay, especially if your read-out is a modern EFIS (they can be calibrated to be quite accurate). But you?re talking about electricity in a gas tank, and the sender is clearly defective. Replace it so you can sleep at night.
 
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