Fuel Float Sender Calibration QB

java · #1 05-26-2007, 08:40 PM

I'm sure I read a post on this somewhere, but darned if I can find it now...

I'm installing the float type fuel level senders in my QB wings. I've bent the wire according to plans (including the last 90 degree bit that seems to have tripped up many), and tested using a multimeter.

What I can't figure out is how to test high and low levels while installed in the tank. I bent the wire per the plans (as I said), but I'm sure there is enough play and variability that it won't necessarily read correctly. Do I just screw it in and go with it? Do I have to "tweak" by filling the tanks for calibration, checking, and pulling out the sensor and re-bending the wire accordingly, maybe several times in multiple iterations (which would suck)?

Thanks in advance.

CRW · #2 05-26-2007, 09:02 PM

I am just going through the same thing. You can bend the wire to the drawing dimensions but once installed there is no way to see what you have. So, I fabricated a cover plate from Plexiglas. I used the standard cover plate as a template and tapped the holes for mounting the sending unit. This probably took me 30 minutes to make and it allows you to look into the tank when the sending unit is installed and see what clearance you have. Turn the wing upside down and that puts the float in the "full" position. Probably there are more "elegant" ways of doing this but this was simple and worked for me.

Chuck

N908RV · #3 05-26-2007, 09:49 PM

Chuck, absolutely genius approach. Simple and effective.

scard · #4 05-27-2007, 08:23 AM

If you made a temporary cover plate out of plexi, or even cardboard for that matter, why not just cut a big window hole in it to reach in and operate the float by hand and see what is going on. Sounds like fun with simplicity

.

java · #5 05-27-2007, 08:42 PM

Great idea Chuck. Thanks for responding. I'll give it a try.

dbuds2 · #6 07-15-2007, 05:33 AM

Here's another way: Just do the sending unit before closing out the tank with the rear baffle. That way you can bolt all the stuff on the the rib and see exactly how it's going to work.

Thanks guys, I'm searching for info about my Van's sending unit and the range of stroke. When I bent it just like the plans, the float never touches the bottom or the top of the tank. Unfortunately, I've got it completely trimmed and I'm wondering if I need another wire to bend and change the bend. Right now, I have about 1/4" to 3/8" clearance to the skin on both the full and empty position. IS THIS OK?

frankh · #7 07-15-2007, 07:01 AM

If you are going with one of the fine glass meters such as a Dynon EMS or AFS etc then you don't need to do anything fancy.

Just bend the float per plans, install and forget about it.

When you come to calibrate the levels you will add 2 gallons at a time and tell the Dynon etc that you just added 2 gallons. You repeat this till the tank is full.

The system than remembers what restistance at the float sender corrsponds to how much fuel.

As long as the float can go full up and full down then nothing else matters even if the sender is only using half of its travel.

Frank

frankh · #8 07-15-2007, 07:04 AM

Personally I would want the float to touch the bottom of the tank so that it is the most accurate where it matters.

Frank

java · #9 08-12-2007, 06:33 PM

Quote:

Originally Posted by CRW

I am just going through the same thing. You can bend the wire to the drawing dimensions but once installed there is no way to see what you have. So, I fabricated a cover plate from Plexiglas. I used the standard cover plate as a template and tapped the holes for mounting the sending unit. This probably took me 30 minutes to make and it allows you to look into the tank when the sending unit is installed and see what clearance you have. Turn the wing upside down and that puts the float in the "full" position. Probably there are more "elegant" ways of doing this but this was simple and worked for me.

Chuck

This idea worked great for me. On my port wing, only small tweaking was required. Thanks again Chuck.

Then I got to my starboard wing. I don't know how, but the float for my right wing drops right onto the flange of the stiffener running lengthwise with the wing, on the bottom (hopefully you can see in the attached picture... wing is upside down... you can see me reaching in with a screwdriver to lift the float to the top (actually, bottom) of the tank, where it rests on the angle).

I double checked things... yes, I have the right sender, yes, the bend seems to fit the plans.

Any ideas to help me?

P.S. From the paint blisters post... you can see the shop heads on my QB tank are covered with tank sealant

scard · #10 08-12-2007, 06:51 PM

Quote:

Originally Posted by java

Then I got to my starboard wing. I don't know how, but the float for my right wing drops right onto the flange of the stiffener running lengthwise with the wing, on the bottom (hopefully you can see in the attached picture... wing is upside down... you can see me reaching in with a screwdriver to lift the float to the top (actually, bottom) of the tank, where it rests on the angle).

I double checked things... yes, I have the right sender, yes, the bend seems to fit the plans.

Any ideas to help me?

It looks to me that you could just turn the float around to (in the picture) point to the left instead of to the right? There is nothing set in stone with these float senders.