A buddy of mine just purchased a 99 32ft. Fountain. After picking it up he decided to add some fuel to the tank. At the the time of fueling up. he turned the key on, and the gauge read between a quarter and empty. After adding 56 gallons of fuel , the gauge was pegged on full. After locating the sender he found a "Full marking on on side, and an "empty" marking on the other side, both have small phillips adjusting screws. He is looking to find out if there is a system to adjusting his gauge. He believes the boat has about 65 gallons of fuel in it and doesn't really want to top the tank off. We have also do not have a hard number on how many gallons the fuel tank is . The boat does have 500 HP's in it if that makes a difference. Thanks for any help.

Don't waste your time trying to get the gauge to be accurate. It never will be. Just a Fountain rule. When it says 1/4, it's really about 1/8. When it drops below 1/4, it's on fumes. It will read full from actual 1/2 to full, so it reads full for a long time. (Just so your buddy doesn't think his boat gets great mileage! )

Mine is a 120 gal tank.

Thanks for the info, I'll let him know. Now when he tells me he's using less gas with his 500's, then my small blocks, I'll know the real truth!

Fuel tank size seems to be a big question on these. I have also wondered are they set up to fill on the trailer or in the water ass down.

I called fountain and they told me 130,,,,, who knows.

I am going to install fuel flow meters,,,,,,,,,,,,,,,,

Ive never been in a boat where the fuel gauge is accurate, rule of thumb is get fuel when your at 1/4 of a tank. I bought my boat last fall and the tank said half, so I went to top it off before winter, it only took 5 gallons. Got the boat in the water needle went to full tank. Unless you want to waste a lot of time and money thinking or adding this or that, just pay attention to whats going on with it, youll know after a few runs and filling up whats in there and what it uses.

Agreed. Just always keep it at least 1/2 full. you will learn when it gets below this. this is my 2nd fountain and my gauge is actually dead on and read correct all the way through the range.

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If the needle even moves off full in mine I better not pass the next gas dock. It might as well have a dummy light

The tank is 130 gallons, you need to fill it all the way up, calibrate to full, when tank gets near 1/2 full, go to gas station, it is closer to 1/4 or less at this point.

Scott Shogren

I changed gauge and sender this year last year when the yellow lite lit it would take 65 gallons to fill. but be carefull they can back up and you are not even close to being full.
Rich