fuel reads full always

[Swervin]

I'm new to this 08 Ranger Tug R25. I have the Cummins and it's reading full at all times. I tried to locate the sender to remove and test but can't locate it. Any ideas?

 

[Bruce Moore]

Bumping post delayed in moderation queue.

 

[Mastercraft]

I have a 2017 R29. Gauge was reading 100% all the time. I took sensor out of tank. The sensor float did not go to the top of tank. It was inherit in design, not broken. I could overfill to 120%. Anything over 100% will still read 100%. I now stop filling tank when gauge hits 100%, so no overfill. This is the rectangular gauge that reads % on top right corner of Garmin plotter.

 

[BB marine]

A fuel gauge reading full all the time could be as easy as calibrating the sending unit to the gauge. Full means the least amount of resistance. The sending unit has steps Full being the least resistance empty being the highest resistance. If a sending unit reads full all the time that would indicate the float is stuck or the sending unit signal wire is connecting to a ground or the sending unit itself is "shorted" to a ground.

The first step is to find the sending unit. The sending unit and all fuel tank fittings are to be accessible. This is a standard ABYC. This recommendation must be met for a boat to be NMMA certified. Rangers are NMMA certified so you should be able to get to the sending unit by removing a panel or inspection plate. Once you find the inspection plate you will be able to pull the sending unit. At this time you will be able to test the sending unit by using an ohm meter. I posted a thread a few years back on calibrating the sending unit. Fluid motion does the basic calibration which is the one step. This is not accurate. It will show full until you have 1/2 tank. In this case using the Garmin is more accurate as long as you reset every time you fill.

This is for the Volvo EVC calibrations. The Yamaha and Cummins have similar calibrations. Using the sending unit to calibrate instead of filling the tank insteps is much easier and accurate. This is the procedure that boat manufactures should use and some do or dealerships should do when commissioning a new boat because the boat manufactures didn't do.Volvo, Yanmar, Yamaha certified technicians are trained during the certification classes as to how to properly calibrates the fuel tank sending unit. When the tank is empty. This is why it should be done when the boat is built or before commissioning. But it wasn't so use the sending unit as I described in the thread. Having an accurate fuel gauge in a boat is important. The new marine fuel gauges if calibrated properly are as accurate as the gauge in your car. We all rely on the gauge in the car but always say the gauge in the boat is not accurate ???? Because it wasn't calibrated!!! Most boat builders or marine repair facilities don't know how too.
viewtopic.php?f=18&t=10780&start=0&hilit=calibrating

If you read through the thread comments it will help you understand how and why if the calibrations are done right the tank gauge will be accurate. I found that my tank gauge was spot on after calibrating it. I always compared it to the Garmin calibrations. The fuel tank sending unit was my go to usually within a gallon of the amount of fuel I took on board when fueling.

 

[knotflying]

If I remember correctly, the older classic 25's did not have access to the connections and it required cutting a hole through the sole to reach it and then install an access plate. Perhaps someone with a classic 25 can chime in on the location.

 

[NorthernFocus]

I've got the same model boat. There's no access plate. There is a copy of the tank diagram that can be downloaded from the documents library on this site.

I had gauge problems early on after buying the boat used in 2014. Elected to simply use the fuel consumption reading from the smartdata display rather than going through the hassle of cutting an access plate into the cabin sole. In my experience simple float gauges in shallow tanks like the one in this boat are not highly accurate anyway. The measured burn rate is more accurate. You just have to remember to reset it when you fill the tank.

 

[PanaSeaAh]

In my '09 R25 there is a round plate above the tank connections and the sending unit. Cannot tell you if it was added. Would not be too difficult to determine where to put it if it is not there. I agree that the Garmin info is more accurate since the attitude of the hull when running affects the tank gage reading.