Anytime, Dave. I suspect your gauge is 0-30 and the sender isn't. Occasionally I'm asked if a sender can be altered to read 0-30 instead of 0-90. The answer is "yes, but it won't be linear when you finish." That means the reading at Empty and Full will be correct but anything in the middle will be wrong...really wrong. Using Ohm's Law I could show how that would work, but I'm not sure it would be worth the trouble...because there isn't a good answer. Several years ago I bought a sender from one of the usual suspect parts providers (I won't mention his operation by name because he just sold the unit, but it is the worst I've ever seen). You can see below how somebody in China converted a 0-90 ohm sender into a 0-30 ohm sender. (hint: they connected an ohmmeter and dribbled molten solder on it until it read 30 ohms. Didn't work any better than you would expect.
A couple of years ago a fellow on another forum to which I contribute said "Oh, just connect a 45 ohm resistor in parallel. Theoretically that works, but again you only get an accurate reading at empty and at full. It is interesting though, if you do the math. The gas represented by the top half of the sender would appear to last a long time and the gas represented by the bottom half would appear to be used really quickly.
If you need a 0-30 ohm sender there's one on eBay being sold by a man whose ID is renbusan. The sender is made in Taiwan and whoever designed and built it did a really excellent job. At $29 with free shipping I could not make a better sender. This realization was what killed my fuel sender project. I heartily suggest this sender above anything else I've seen anywhere...and I bought about $175 worth of various senders when researching them. Three reasons: the wiper contacts tiny metal fingers and not the resistance material. This will make it last longer and be more accurate and linear over time. The wiper wipes in a flat motion and not in an inverted half-moon arc. The upside down arc wipers are cheaper to make but the wiper loses contact with the arc after just a little wear and then it becomes erratic. And finally the body is made of nylon...which isn't bothered by ethanol. It may discolor, but it won't melt nor dissolve. This should take you there:
https://tinyurl.com/jt8kphpn
