Probably just need a sender for the tank. There not that expensive from WEST or BOATERS WORLD.

testing sender unit
 

Is there a way to test the sending unit to see if that is the problem without having to take it out of the tank?

Many here will say fix it!!

I on the other hand say screw it! Unless you going off shore you will never need all that gas, so if you fill up each time you have nothing to worry about!!

Here you go
 

Check out this site http://www.nls.net/mp/volks/htm/fuel_ga.htm

The sending unit ain't but about $20. The gauge working is a good conversation piece.
Replacing the sending unit also gives you a chance to explore the tank for debris like water and stuff by siphioning the bottom.
If you remove it, go ahead and replace it, gasket and all.

By the way we (have to) tolerate MJ's V-OX, so a V-20 ripoff will be accepted.
Go ahead and price a new boat that length, $25,000 and uuupp.
Keep workin on it and posting pictures, the boat's worth it.

welcome aboard, we need medical advice on this site..
we also need some sample meds, i'll pm you a list of my personal favorites

i second mj's method. start with a full tank and your trip set on the gps on 0. do an average trip, & fill it, then figure your mileage. this way you can get a very close estimate on fuel used and fuel left. i haven't had a working gauge in 10 years.

My gauge doesn't work, so I always guess.
Yeah I am an engineer so I should be able to
calculate in my head how much gas I am using.

Well, I was having problems with wtaer and debrie clogging filters,
so I was peroccupied with cleaning the filter every hour,
so when I saw that someone else on the site found the racor
filter on ebay for 20 bucks, I jumped on it.
It was an over run of SEA PRO re names.
I put that on and no problems this year.

Now to get back to gas gauge.
I still think I may replace my sending unit, just casue I have an extra $30 -$40
laying around.

Oh yeah, Dr. B, when I first saw your name,
I did picture this cute little blond working on the boat,
wearing a skimpy bikini.
Oh well now I have to go back to Stinky working on his boat in a pink thong.

I and CB bought the same filters they work great!!