New Fuel level gauge - what ohms?

[flying07]

Hi all. . . . replacing the gauges in my 2002 GS. Already did new GPS speedo and tach. About to order the others, and I see the 'fuel level' gauge can either be 240-33 ohms, or 0-90 ohms. As I'm poorly trained at electrical, anyone know what I need or what these even mean? Thanks!!

 

[Jon]

A small amount of current is sent through the wire, through the fuel sender (which works as a large adjustable resistor - rheostat), and it returns to the gauge which reads that current. Voltage stays the same at 12.x+ or so, and by changing the resistance, you therefore change the current (ohm's law).

I actually don't know which setting you need, but it will be based on the sending unit in the tank. Is your sending unit in the tank stock?

 

[flying07]

Won't lie, that brought back some college physics! At least for the small amount of time I was awake during it. Ha ha. Thanks for the great explanation!!

The sending unit is stock in the tank to my understanding. How to get more information, that I don't know......

 

[Jon]

Ohm's law is a good one to remember... and if you want to do anything like Maxwell's fun differential equations, well I'd have to brush up. I effectively remember how things work, just not always how to arrive at the answer

Maybe the manufacturer of the gauge has some specs? Do you have a URL for the gauge?

You can pull (easily on a GS) the sending unit, drop the float completely and measure resistance, then move it to the top and measure again. This should give you some indication of which setting to use based on manufacturer recommendations. If you do have a link, I can try to look at it.

 

[flying07]

Jon,
Thanks! oh the joys of physics. . . haha. . . . here are the two links. . . . I'll make a call to CP Perfomance and see their thoughts as well

http://www.cpperformance.com/p-16673-livorsi-fuel-level-gauge-240-33-ohms-mega-race-rim-2-116.aspx

http://www.cpperformance.com/p-16675-livorsi-fuel-level-gauge-0-90-ohms-mega-race-rim-2-116.aspx

I'm sure someone knows the answer. . . haha. . .

 

[Jon]

Let me know what you find, because their spec sheet is VAUGE . The 0-90 looks like a GM specific product for GM MEFI applications.

http://www.livorsi.com/vol18/volume_18_gauges.pdf

 

[flying07]

yeah, tech sheet is awful, isn't it? I contacted them via email, I'll let you know as soon as I find out.

If only it could be simple. . .haha

 

[bassracr]

just a thought,if you are replacing a gauge that seems to work ok ,and using the same sender.. check the back of the old gauge for an inked or stamped resistance value or maybe a model # that you could google the specs. for

 

[flying07]

Great idea bassracr! sadly, darn thing is blank. . . haha. . . just spoke to Lovorsi, they said that 99% of them are the 240-33 ohms, so we went with that one. Was able to look up Faria/Beede Specs, and looks like 'American' Senders are all 240 empty, to 33 ohms full, so should be correct unless Bill is putting European senders in! haha. . . . If it isn't correct, they will swap it out. So i'll keep everyone posted! thanks all!

 

[Jon]

From what I read, the 90-0 is a one off for GM only. They wanted to be difficult.

And jeez... bassracr wins this one for pointing out the right place to start looking!

 

[flying07]

He does! why didn't we think of that. . . but now I know Ohm's Law. . . haha!!