Hello JanC,
jimh here; I am the forum provider and the continousWave website provider. Welcome to the forum and the rest of the website.
Your question is not a bother. The forum is an interactive way to share information. Asking questions is the best way to initiate a discussion.
Congratulations on the 1984 REVENGE 22 boat. I am a big fan of the Boston Whaler REVENGE boats. I have owned two of them. My current Boston Whaler is a 1990 REVENGE 22 Walk-Through Whaler Drive.
Now on to your questions.
The fuel tank in your boat is almost without question a product of Florida Marine Tanks (FMT), if the tank is aluminum. FMT is no longer in Florida; they moved to the Carolinas. They still make fuel tanks and can supply a replacement tank.
The FUEL TANK LEVEL INDICATOR on your boat is also very likely a mechanical gauge that is mounted right on the fuel tank and is visible by looking through a clear circular deck access plate in the cockpit deck. If this is the gauge type you have, the indicator is actually coupled to the tank level rod by a magnetic coupling. Sometimes the magnetic coupling can be interrupted, for example, if the boat is run in high seas and takes a hard landing off a wave. But usually the magnetic coupling fixes itself.
The mentioning that you have a fuel tank "gauge" and a "sending unit", however, make me think perhaps this particular boat has an electric remote fuel tank level gauge.
Please give a bit of clarification:
Q1: is the fuel tank aluminum?
Q2: is there a circular clear deck access plate in the center of the cockpit deck that shows the fuel tank level?
Also, since you are new to the site, I must tell you that in addition to the forum there is a huge collection of information in other areas of the website, particularly about Boston Whaler boats. In the WHALER section in the REFERENCE subsection there is an article on OEM Suppliers and Recommended Vendors. In that article there is information on the magnetic fuel tank level indicator gauges. See
http://continuouswave.com/whaler/refere ... #fuelGaugeIn that same article there is information on fuel tanks, particularly about Florida Marine Tanks. See
http://continuouswave.com/whaler/refere ... l#fuelTankAnd if you need a circular pry-out deck plate, that supplier, BECKSON is also mentioned in the same article. See
http://continuouswave.com/whaler/refere ... tml#pryoutSo no need "to wait for Phil"--a great contributor and also a moderator who you will soon learn to value as a wise Boston Whaler fellow.
If you don't have a clear circular center access plate but there is an opaque tan circular access plate on centerline and just behind the helm seats, then very carefully and using a wide blade large straight screwdriver pry-up that access plate. The fuel tank level sender should be right there.
Rather than just give you a short answer, I like to inform you where you can find a much longer answer with direct links to vendors. That's in the REFERENCE article in the WHALER section I gave URL's for above. Another VERY IMPORTANT reason I like to link to fixed articles in REFERENCE that contain information is to allow updates to the information to made just in one place. These days the content of websites changes all the time, and often links become deak links. Rather than scour the forum looking for dead links, it is easier to just fix the links in one place, in the REFERENCE article.