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Fuel sender ohm reading?


jiminyfixit

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It may be comatose because it is dirty or corroded inside.  I was able to bring my sending unit on my 1928 Chrysler back to life by cleaning it with an spray can electrical motor cleaner which leaves no harmful residue behind.  Then someone posted this test procedure.  My unit looks like this.

Hi

Very easy to test a sender unit.

Its just a variable resistor -  usually connecting the gauge wire to ground via the sender resistance coil.

All you need is a Ohm meter. Here's how-

Just connect one lead of the Ohm meter to the centre terminal of the sender unit and touch the other test lead to somewhere on the metal case of the sender.

You should see a reading on your meter that changes as you move the float arm up and down.

Typical readings may be around 10ohms for full to 150ohms empty . These values may not be correct for your sender they are a guide only.

If you cant get any readings you have an open circuit in the sender unit.

Also when testing make sure your test points on the sender are clean so that you get accurate readings.

Good luck 100_0910.JPG

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Leomara,

 

I appreciate your speedy reply. I sanded the sender body in one spot to get to bare metal, set my multimeter to 200 on the ohms setting, moved the arm up & down & got zip. I will try the electrical cleaner & see what happens. This poor sender & the tank are in horrible condition. The amount of build-up in the tank has created a lot of sound deadening, a fully plugged pick up tube & I'm not real excited about using Muriatic acid or anything else like that, due to a lack of environmentally correct disposal options. For the price, a new tank is a better option, (ordered 2 days ago), and will eliminate the angst of having possible issues later down the road. There are many fuel sending units out there, but I want to be sure I get one that is within the working range of the fuel gauge, even with minor adjustment.

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If you take the sender apart, you can then measure the resistance of the wound coil itself.  Carefully clean the ends of the coil where it attaches to the terminals. Measure from those points.  This will provide a close "empty" value. The actual value would probably be slightly less depending on where the "wiper" contacts the coil when the float arm drops to it's lowest point.

 

Keep us posted.

 

Paul

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