Fuel Gauge Calibration

[BeachFarmer]

Greetings:

I have a '08 Supra 21v that I purchased new this year. It has a 40 gallon fuel tank. My fuel gauge (analog and digital) always read less than whats in the tank. For example, I can run the fuel down so the fuel gauges read E or 0% when the boat is level or with bow up upon acceleration. When filling the tank, I can only put approximatley 29 gallons in which suggest there is still 11 gallons in the tank. When the tank is full, the max I can get the gauges to read is just over 3/4 tank or 85% on the digital readout. How do I calibrate the gauges? Can I do it under the dash or do I have to pull the floor up?...thanks in advance...j

[sniperside]

as a point of reference, my 08 21v exhibits the same behavior you described on the trailer (max 84% fuel). the correct measurements of fuel (and most fluids) in on the water where the boat will sit at a different angle than on the trailer. having said that, supra did built a decent reserve on the fuel tank so you can run on 0% for a while although I WOULD NOT recommend it. faulty fuel pump caused from overheating can be a pain to replace

[jaywidhalm]

When my 08' 22 Sunsport is completely full the digital guage reads 97 percent. When it says 0 percent, there is about 4 or 5 gallons left in the bottom. I don't think the gauges should be as far off as yours is stating. Totally full showing 85% is quite a bit. I am not sure if you can calibrate the gauges, so I am sorry I didn't help answer your question. Just wanted to let you know what mine reads.

[BeachFarmer]

Sniperside/Jaywidhalm:

Thanks for your posts. Given the degree of descrepency in the gauges versus what is in the tank I spoke to the tech at the dealer. He led me through a diagnostic program at the console and the guages are fine. He indicated that it could be the sender. I pulled the floor and the sender and it appeared the float on the sender was sliding just fine. However, the length of the sender compared to the depth of the tank at that location led me to believe that it may be the sender for a 34 gallon tank which are installed on the 20v. I indicated that I would measure the length of the sender so the dealer can compare against spec. If it is the correct sender, it must be faulty. While I appreciate fuel gauges showing E with a small reserve left, there shouldn't be +25% error in the fuel reading. Yes, I can do the math each time I fill up to figure when to refuel based upon fuel consumption per hour; however, I didn't drop this amount of coin on a boat to be a mathmetician!

[mapleleaf]

good call.....hope you get all the you need getting this resolved....

[Skylar18]

I have the same issue. When full my guage says 84%. Depressing when I put 150 bucks of gas in the boat and still is not showing full.....

My wife takes out the boat with the kids alot and our rule is to never be out there with less than a 1/4 tank of gas. On my boat when the guage is showing a quarter, there is actually just less than 1/2 a tank of gas.

[saltare inverts]

My boat has similar readings. When it is reads 1/4 of a tank it has more than a third of its capacity left. I believe its a safety feature coupled with generic sending units.