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Vans fuel senders

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Freemasm

Well Known Member
Possibly the dumbest question ever.

Background: My wing kit came with a set of very old senders. I used them to match/configure my tanks. Reading on VAF that the older senders had problems, I ordered new ones. Now, the right tank mounting hole pattern doesn't align to the new designated "right" sender but the designated "left" one does. I think I've checked everything. I cannot find a difference between right and left sender units proper other that the mounting hole pattern.

Is there any real difference that I'm overlooking?

I have no desire to re-do a section of a newly built, non-leaking tank (knock wood) without good technical reason. Thanks.
 
Unsure about the mixed up screw hole pattern... or mixed up senders in boxes... or mixed up access tank cover plates...
Suggest you mock up the 2 new senders oriented per the plans and insure they work according to the statement below.


"rvbuilder2002 ...
... The standard sender has a resistance value of 240 ohms at empty, to 30 ohms at full."


Then if all checks out, install the one that fits. If the float offset becomes the issue, than a bit of modification or fabrication of the wire float arm may have to be done.
 
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Is it possible that you ordered two senders of the same part #?

The way things are designed, when you install the cover plates they are mirror images of each other and the hole pattern is clocked in such a way that the same sender can't be installed in the left and the right tank.

If you have the access covers installed correctly, a left sender will only install correctly aligned, in the left tank and a right sender in the right tank.

When a sender is installed correctly, the metal arm that the sensor is attached too will be angling at approx. 45 deg downward/inward towards the bottom of the tank
 
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Another question regarding fuel sender arm and quick build tanks. How do I check the travel of the float to ensure full travel with the recommended 1/16 gap from top and bottom skin when the tanks are closed up? The plans have this step done before the tanks are closed.
 
rnewcomb7797 said:
Another question regarding fuel sender arm and quick build tanks. How do I check the travel of the float to ensure full travel with the recommended 1/16 gap from top and bottom skin when the tanks are closed up? The plans have this step done before the tanks are closed.
Click to expand...

Lay wing down in ?in flight? orientation. Hook an ohmmeter to the sender terminals. Insert the fuel sender, hold by hand. Rotate so the float is off the bottom, should read 240 ohms or so. Rotate the float down, note when the reading starts to go lower. You just bottomed out. Check where the holes line up.
Flip the wing over and repeat, this time looking for 30 ohms when the float is off the ?top?. I adjusted my -10 floats so they were just bottomed out on empty, as empty was where I wanted accuracy. At ?full? is not so important, as the wing dihedral will cause the float to hit the top a few gal short of full anyway.
 
clamp the sender on the corner of the tank so it's vertically at same height as when mounted, swing the arm up and down in reference to the top and bottom skin, adjust arm as required.
 
There is no difference between the left and right senders other than screw pattern in the flange for the reason I previously mentioned.

Perhaps you installed the cover plates on the tanks ribs backwards when you were building the tanks. That would make the left sender go on the right tank and vise versa.
The only potential problem with this might be a difficulty in not having the float hit the stiffener angle on the bottom of the tank because the actual sensor portion of the sender would be off-set to the opposite side of what was intended.

If you can make the float work properly, it doesn't matter which sender is at which location.

BTW, the old send problem you read about was with an actual wire wound resistor sender. They were phased out of use in the wing kits in the early to mid 90's.
Any sender that has a white plastic sensor assembly is the new style, so what you already had installed should be fine to use.
 
Simpler than that

The “mistake” was actually simpler than that. I used the original senders to locate the hole pattern for the tank fab. I assumed the senders marked left and right were indeed such. As the old didn’t match the new for one side, hence the dumb question. I understand the asymmetric hole pattern to keep future clocking mistakes away but by that token, there’s no similar foolproofing concerning the access plate where the fuel suction, senders (sometimes), etc are connected. As typical, I over complicated it. If it were mega critical, there would be a left, right and “other” for second bay installs when avoiding flop tubes.
 
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