Aftermarket Year One SS Fuel Sender...how to get calibrated?

[kawahonda]

Hi all,

My OEM fuel sender is crusty, float is shot. It's perhaps worth restoring, but it will take time and effort.

I have a Year One SS fuel sender on order. I need to know what all to do to ensure accuracy.

I know that 22ohms is the "half way" point resistance.

I know that bending the tabs on the sender is a way to make sure your dash gauge reads all the way empty, and your gauge reads all the way fuel.

What I wonder is how to calibrate the in-between areas, which I assume is the function of bending the float rod. I don't want to have burned 1 gallon of gas from full, and then for my gauge to tell me I'm at 3/4. Or for my gauge to tell me I'm empty, but I have 5-6 gallons in the tank left. All of these cases really defeat the purpose of having a fuel gauge in the first place!

Maybe I'm over thinking it. Maybe the Year One sender is plug and play, just let 'er rip.

My thought regardless is to do a "dry run" by laying the tank on the ground, measuring and filling the tank up with water, and making sure the sender sends accurately to the dash gauge.

How much fluid should be in the tank when the dash gauge reads all the way empty? 2 gallons?

Would like to know your methods and experiences. I want to "do it once, do it right."

[BIGSHCLUNK]

In my experience the new aftermrkt senders ALWAYS need tweeking... I had mine out 3 X before it was "close" to my original. The word here is "close" , never have I got perfect. There's been many posts on this issue. Maybe someone's had better luck...   

[Jay Bee]

I just tossed a SS sending unit I bought off of ebay. It benched tested okay with an ohmmeter but was WAY off in the car. Yesterday, I sprung for a Spectra Premium one which seems to be better. Sorry if I burst your bubble, maybe you'll have better luck. I think Dave at Roseville sells the Spectra Premium ones.

[BIGSHCLUNK]

And ya... mine is also a Spectra..     I'm really good at getting these out quick! 

[kawahonda]

Sounds like I have the right idea of keeping tank uninstalled for awhile, filling it up water, and just making sure it's nailed.

I just need some specs. How much gas should be in the tank when it's "E" on the gas gauge? 1 Gallon?

Full should obviously be 18 gallons?

Halfway point is 22ohm...

[kawahonda]

Can anyone tell me the min and max positions on the non rallye gauge?

[CudaMoparRay]

Can anyone tell me the min and max positions on the non rallye gauge?

If I understand your question correctly it should be Empty = 73.7 Ohms Midway = 23.0 Ohms and Full= 10.2 Ohms

[kawahonda]

Thanks. I'm currently playing with my old and crusty sender. I've cleaned it up some, but I'm curious if it's junk or not.

I meant the positioning on the gauge itself. Here's currently what the sender is showing up as on the gauge.

See pics for all the way empty, and all the way full. Should I expect the needle to go all the way up, and all the way down on the bracket line?

If the gauge has a resolution of only 1/4 intervals, then it looks like I'm close...just need to tweak the "finger" some more.

My OHMs are pretty close to what's expected to stock specs. I'm getting 13 ohms for full, and 74 ohms on empty.

If the needle is expected to go ALL the way to the end of the bracket, and ALL the way to the top of the bracket, then I'm way off.

[BIGSHCLUNK]

Mine shows ( after 3 adjustments ) a little less than what I actually have.... better that way than showing more an running out...   

[RUNCHARGER]

They will usually point right to the "F" when full and the needle won't move when truly empty. So basically the needle should swing full range. To be honest though when new they all might have just been calibrated a tad different.

[kawahonda]

Here's a picture of my "off" position isn't this the lowest possible point? Or is this incorrect?

I looked at a parked 70 Cuda today and it was the same thing.

But I think that answers my question  I should be seeing the needle move throughout the bracket space if I'm hearing everyone correctly...

[RUNCHARGER]

Okay: Then if you added 2-3 gallons of gas I would want that needle to move onto the next calibration mark when you turned the key on. There is really nothing you can do to change the off position of course, but I want them to move with say 2 or 3 gallons of fuel in it. In my mind the empty to 1/4 full calibration is more important than the full.

[kawahonda]

OK, I've spent about 2-3 hours rebuilding, calibrating, and testing the original sender. It looks like this is a 1/4 increment gauge...the needle should only move to the tick marks during fuel readings and should NOT move past to the "bracket ends".

My final calibration was:

73 Ohms     (empty)
12.4 Ohms  (full)

I cannot lower the 12.4 Ohms without affecting the 73 Ohms number. I was pretty upset about with the 12.4 reading....until I actually plugged it up to the car.

You can't really get anymore perfect that that...

It works throughout the whole range. I trust it. Even after I broke one of the mounting tabs to the box on the backside, I still trust it! (box is still very "tight'). Going to stick a new sock filter on it and re use it. I cancelled my Year One sender order.

[RUNCHARGER]

Good work, they are readily available if this one croaks. The new ones aren't that great to be honest.

[Bullitt-]

My experience with my Challenger, and about every pre-'90s vehicle I ever had, is that it takes a long time for the needle to come off of Full & that I would get almost twice as many miles out of the first half of the tank as the second as indicated by the gauge. I believe this is caused by the float being pushed below the surface when at the top of the tank when full so don't be surprised when at 1/2 indicated you actually have less than 9-gallons (1/2 of 18). Empty was still accurate but comes faster than you might imagine.