THis is for the '55 Chevy. I’m looking to hook up a Stewart Warner aftermarket fuel level gauge. SW provided a float and sensor which has a range of 240-30 ohms (30 being “full”). Problem is is I cannot use this set-up as the new fuel sender that is in the new gas tank has a float, sensor, and most importantly the fuel sender for the EFI built into it (bought from Ecklers Classic Chevy). This sensor has a range of 0-30 ohms (30 being “full”).
So how can I run the SW fuel level gauge with the current sensor? I’m a bit dumb when it comes to this, but simple math tells me the SW gauge is calibrated with a range ~7 times “less” than the Eckler’s sensor.
It can be done, but that doesn’t mean it should. I’m not being that guy telling you to get the correct part without knowledge of what would need to be done for it to do what you want to do. Trust me. Not worth your trouble for a such a small detail. For your case, get a gauge with correct ohms range needed. 30-240 is a common universal ohm range for fuel sensors providing a 73 to 10 ratio sweep for accuracy.
Problem is is the gauge is part of a 6-part set, and the sender I currently run is specific to the tank. I don’t really see an easy way to get rid of one or the other.
When you say it can be done, but shouldn’t…what are the negatives?
first find out what voltage the gauge sends out, then I think you can use ohm’s law to calculate what resistor you need to run. Since you want more voltage to the gauge, you’re going to want to run the resistor in parallel with the sensor.
Grr, actually, It might be more complicated than that… because that will just add a constant to the voltage value…
JK…thanks for the help so far. I’ve got a few other forums to check out, as well as another few calls to Ecklers and SW to see if I can get a better tech that can offer something up. Both occasions that I’ve called them they didn’t have much of any good info for me.
newman is right on the money with this one.
I was at first thinking resistor in parallel and they bounced my head off my desk thinking of what an idiot I am. Your value needs to change in relative terms, meaning it’s not just as simple as a resistor in parallel. Either design a small control circuit which can essiently “read” your input ohms and make the proper adjustments to your output via an eeprom chip of sorts (which would be small and compact, but someone would have to design it for you). Or, the more logical way as newman suggested, would be use a transformer to step your voltage, but you’d still have to make circuitry to give it the correct “step”. Almost too much work for what it’s worth, especially if you don’t have the knowledge to DIY. Maybe some electronics guy on here could build you one as a side project. I personally don’t have time to do that stuff at the moment.
OT: Hell Newman, your bro could rip off this little project in no time at all.
edit: that link you posted will not apply to your application.
*SW gauge and sensor 240-30 ohm
*Ecklers sending unit with sensor 0-30 ohm
Bascially, couldn’t find a way to wire this up so that the two correlated, so I did the next option and swap sensors on the sending unit. I had an extra sending unit to use as a constant refernece point for sensor and float orientation:
My card got full so I didn’t get a chance to snap pics of the float, but that was just a matter of needing and trimming the wire to match. Now I can run the sending unit for the EFI, and the gauges that I wanted:)
