Fuel Sender

[RVG8tor]

I am getting ready to close the tanks and I was testing my fuel senders (float) and I am not getting the numbers that Van's shows in the instructions (30-240) The instructions do say about those readings. Well I get 31 at the full end and 196 at the empty end. My concern is the float has to move a few degrees off the empty end before it starts to read any ohms at all. The funny thing is that both of my senders do the exact same thing, no reading until they move some and then the first number I get is 196 ohms at that goes down to 30 as the float reaches the full position.

I called Van's assistance and got the not so helpful "wow not sure I have heard of that". We talked and thought since both gauges read the same they both must be working. I have an EFIS/EMS so those it's fuel display will get calibrated to whatever the sender reads as you add fuel in 2 gal increments. But I wonder if 2 gals will be enough to make the sender actually float up enough start sending out a number.

Thanks for any help here. If you had a similar issue I would like to hear from you. I have searched the forum but so far no one states the actual numbers they are getting at the sender stops.

Cheers

[Jeff A]

Mike,
I don't think you have anything to worry about in regard to the resistance of the senders. Like you said, they will get calibrated to the EFIS, and it will use whatever value it is presented with. As far as 2 gallons being enough to make the sender indicate a change in resistance is dependent on how low the float sits in the tank. If the float is touching, or nearly touching the bottom skin, then 2 gallons will be more than enough for the first calibration point. My Skyview calibration had a change at every 2 gallons up until 16-18 gallons per tank, where the sender was maxed out in travel. No change in fuel level is indicated until you burn 3-5 gallons out of each tank. Good luck.

[RVG8tor]

My float sits near the bottom but must travel a bit before any ohms register. I had a Vans gauge on hand so I hooked that up. As I move the float arm it jumps from zero to 2.5 gal mark or just below it actually. As I move the arm further the needle steadily moves then will make a jump after 5 gal mark. It makes two more jumps like this before it reads full. Letting the arm settle back to the tank bottom the gauge will stop at 2.5 gal. I think there is dead band between 0-2.5. The weird part is both senders do almost the same thing. I sure don't want to install these to have to take them out again.

Is the jumpy indication normal.

[RVG8tor]

I solved my dead band problem at the low end when I realized I was setting the meter at 200 instead of 2k. Now I get readings through the full range. What a knuckle head! The reading is still jumpy with the Vans gauge but since I will use my Dynon I am not going to worry about that since the calibration process will handle this.

happy but humble!

[Jeff A]

As I don't know what the internals of the Van's gauge look like, I would suggest that the only accurate measurement of the probes resistance would be with a digital multimeter....which is essentially what your EFIS fuel gauge input is. The jump you notice might be more of a gauge issue than a probe issue. I would recheck the probes with a multimeter, and if no dead spots are seen, install them, and calibrate per Dynon's instructions. I don't think you are seeing anything different than anyone else with a resistive fuel probe would see.

FWIW, not sure if you are installing a fuel flow transducer, but in the few hours I have so far on the RV, I rely on the fuel flow/fuel computer far more than the fuel level indications.

Hope the input helps at least a little....

**Looks like you replied before I could get my thoughts complete** Good luck.