Sending Unit Ohm correction?

[Sh1fter]

I have a 63 Nova. I believe the sending unit is a 0-30 ohm. I need to switch to a fuel cell. The only fuel cells that fit my needs come with 0-90 sending units. The manufacturers will not swap in 0-30 units. I would like to use my original fuel guage. Is there a way to run an inline 60 ohm resistor..is there such a thing? Thanks.

[69NovaSS]

I have a 63 Nova. I believe the sending unit is a 0-30 ohm. I need to switch to a fuel cell. The only fuel cells that fit my needs come with 0-90 sending units. The manufacturers will not swap in 0-30 units. I would like to use my original fuel guage. Is there a way to run an inline 60 ohm resistor..is there such a thing? Thanks.

Well firstly Welcome to the site:)

This issue has been discussed often on this site and I really dont believe there is an easy solution. The problem with adding the 60ohm resister inline (in series) with the sending unit is that now the resistance of the circuit is 60-150 ohms...as the total resistance of a series circuit is the product of all resistance in the circuit. (I am sure this is how it works BUT it has been a few years since I last had to use Ohms Law) So in this case the lowest resitance the circuit would see (when the tank was empty) would be 60 ohms...and the highest it would see (when the tank is full) would be 150 ohms...so as you see this is going in the wrong direction...

Now you could try adding a resistor(not the 60 ohm one I suspect it would be smaller than that...possibly in the area of 45 ohms) in a parallel circuit and this would somewhat work...so that when the tank was full the guage would only see 30 ohms...the problem would be with anything BUT a full tank...I dont believe that it would ever display empty correctly for you...your car would be sucking fumes yet your guage would still say you had gas....

Two other solutions I can think of are having the guage re-calabrated to work with a 0-90 ohm sending unit...likely $$$ if it can be done.....or having the sending unit itself re-calabrated to work with a 0-30 ohm sending unit....again likely $$$ if it can be done...

I guess the easiest solution for people in this situation is to use either an original style tank and sending unit OR to use an aftermarket fuel guage designed to work with a 0-90 ohm sending unit...I'm sure others will chim in with information but I believe this is the outcome that others have found...

Again...welcome to the site....:)

[Custom Jim]

You could remove what sending unit is in there and replace it with one of these:

https://www.classicinstruments.com/productother.aspx?ProductCode=SN36

It fits tank depths from 6" to 24".

Jim

[69NovaSS]

You could remove what sending unit is in there and replace it with one of these:

https://www.classicinstruments.com/productother.aspx?ProductCode=SN36

It fits tank depths from 6" to 24".

Jim

Custom Jim;

Would that work correctly in a fuel cell...normally they use floats that are more like bobbers they go straight up and down they dont pivot on an arm like that....i think this has something to do with the foam a lot of fuel cells have in them...:confused:

[DriveWFO]

Custom Jim;

Would that work correctly in a fuel cell...normmaly they use floats that are more like bobbers they go straight up and down they dont pivot on an arm like that....i think this has something to do with the foam a lot of fuel cells have in them...:confused:

My new fuel cell has a sending unit in it and I think the float is hidden inside a vertical plastic tube, otherwise, the foam would keep it from doing its job.

[69NovaSS]

My new fuel cell has a sending unit in it and I think the float is hidden inside a vertical plastic tube, otherwise, the foam would keep it from doing its job.


Thats whats I thought...I had a feeling the foam would be a problem for a pivoit style float...:)

[DriveWFO]

Thats whats I thought...I had a feeling the foam would be a problem for a pivoit style float...:)

Yup, looks like this:

http://static.summitracing.com/global/images/prod/large/sum-290181.jpg

[Raymond]

I went through all this stuff last year.....use what Drive just showed you,it's a 90 ohm sender for the cell,now go buy a nice fuel gauge to match....my problems are over,yours will be too. I also wanted to use my original guage but some things can't be helped! Good luck!

[Sh1fter]

I guess I can mount the tach in front of the fuel guage now.

[Philip]

I am not familiar with 1st gen dashes but I'll throw this out anyway. In 65 GM switched to the 0 - 90 ohm sender and gauge across most of its car lines. So if a 65 gauge is the right ohms and will fit your problem can be solved. Any 65 owners out there that can help?