Should I replace my Fuel Float?

[luckyinkentucky]

Yesterday I went to Ski Day on the Ohio, and I filled up before I left. Before I beached my boat I noticed I had 1/2 a tank left, and that was to be expected since I took 6 people down there with me and it was a 30 mile run.

On the way back I was 2 people short due to them staying there, but I was on a 1/4 of a tank before docking at home. I looked in my tank and it was still half full.

Now, this is the thing. I should have only used 1/4 of a tank on a 30 mile run either way, but why did it say 1/2 had been used on the trip there? Could my fuel float need to be replaced? I have a 41 gallon square tank.

 

[dingbat]

Re: Should I replace my Fuel Float?

You most likely have the "arm" type sending unit which is notoriously inaccurate.

If you want something more accurate you could go with the inductive type sender or you could forgot the sender all together and go with a flow monitoring device.

I have both but have come to rely on the flow monitor as the last word on fuel consumption and fuel level.Run you about $120

 

[Silvertip]

Re: Should I replace my Fuel Float?

You need to do a little thinking about how a float in a gas tank works. It swings through an arc. Therefore when the boat is at different attitudes, the fuel in the tank is always level but since the upper part of the float assembly is attached to the tank, the float arm sends a different signal to the gauge. When calibrating the arm (moving the float in or out on the arm or bending the arm) you can only adjust for one parameter. You can adjust for accuracy at E, 1/2, or F but not all three. It's just simple physics. Another example of inaccuracy is with an irregular shaped tank. A cone shaped tank for example is not half full when then the fuel level is half way up or down the cone. The wide half of the cone holds more fuel than the narrow end of the cone. So at 1/2 full (level) there is more fuel in the lower (wide end) of the cone that at the top (narrow end). My boat has a long, narrow, shallow tank and I too use a fuel computer because of the inaccurate fuel gauge. The fuel computer uses a transducer in the fuel line to measure the amount of fuel passing through it and gives you 15 second updats on fuel used, fuel remaining, fuel flow rate (gallonss/hour) total fuel used and total used this trip.