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RV-10 Fuel Sender Resistance

ydna

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Previously, I saw something about the sender rod not being bent properly which could cause it to interfere with internal structure of the fuel tank preventing full travel. Has anyone verified full travel of the sender and then measured the resistance when tank is full and empty?
 
Previously, I saw something about the sender rod not being bent properly which could cause it to interfere with internal structure of the fuel tank preventing full travel. Has anyone verified full travel of the sender and then measured the resistance when tank is full and empty?

The max resistance range of the senders is easy to find, however, the full up down travel in our tanks is less than the full range. I tied a string to the end of the arm and fed it through a hole. This allowed me to confirm that the arm was not hitting anything.

I have not measured the installed range on my unit.

Larry
 
That?s the stop to stop range of the sender. As pointed out in post #2, top of tank to bottom of tank is a bit less. I filled my tank from empty to full, in 5 gal increments, to calibrate the senders. They max out at about 25 gal, due to the wing dihedral.
Before installing my wing, I turned it over, and I thought I could hear the float hittng the top skin, and the bottom skin when I turned it back right side up. Of course, if it was hitting some internal structure, maybe it would sound the same. -:)
 
RV-10mFuel Sender Resistance

Thanks for the responses. I installed the sender in the right wing tank with the right wing positioned up. The resistance was open/no resistance. I expected to have some resistance. I removed the unit and discovered I had to move the float 10 to 15 degrees up before I had a resistance reading. The reading started at approximately 194 ohms. I checked the bends in the rod according to the plans and all appeared proper. I then went to the left wing sender and removed the sender from the tank to check it and received the same results as the right wing sender. When I initially installed the left wing sender, the wing was positioned down. At that time, I had a resistance of approximately 34 ohms which would have been a full tank position. I did not turn the wing over and test the resistance for empty. Question: Are my senders defective or is this the norm?
 
You should have some resistance across the entire travel of the arm, from empty (float on floor) to full (float hitting top). Did you follow the manual for making the bends in the rod? I am guessing maybe you didn't and sender is moving to the end of it's allowable travel before hitting the bottom or top skin. I have never tested, but woudn't be surprised that it meaures open when hard against it's own stops. You need bends to have your extremes of travel within your tank be slightly within senders extremes of travel.

Larry
 
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I removed the unit and discovered I had to move the float 10 to 15 degrees up before I had a resistance reading. The reading started at approximately 194 ohms. ..... Question: Are my senders defective or is this the norm?

This is not right, sounds like the resistance wire is broken at 194 ohms. To test this theory, note the position of the slider where you first see 194 ohms. Put the float where you read infinity. Put a large flat blade screwdriver, flat side against the wires (where the slider makes contact), in the vicinity of the 194 ohm position. Move it around a bit. Do you now get a reading, like 230 ohms? If so you need a new sender. My recollection is that I saw a reading, stop to stop, when I tested mine.
 
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