Fuel Gauge Always Reads Full

[Capt Tom]

This spring I bought a new to me 2011 205 Freedom. The first time I used it the fuel gauge was reading full, ran guessing around 40 miles and and it never moved. Good thing the tank was full because when I refueled it seemed about the right burn. I have the square Yamaha Command Link gauge and as long as I top off before
each trip I should never run out of gas but nonetheless it would be nice if it worked.

 

[mhinch]

My understanding is that if it's reading full it's either an open circuit, no resistance, or a bad ground. Check and clean the ground first then check the resistance of the gauge. The make and model number should be on the top so you can then research what values you should have. Please report back to us.

 

[DennisG01]

Go to the sending unit for the tank (probably an access deck plate). With the key on, remove the pink wire. The gauge should go to zero (give it a few seconds to respond if it's a digital gauge). Touch the pink wire to the tank ground. The gauge should go to full. If it doesn't double check with another good ground. If the gauge responds properly to these tests... replace sender. If it still doesn't respond, issue is from the tank wiring to the gauge.

Fuel gauges work by Ohms. Low resistance gives higher/full readings, while higher resistance gives low/empty readings. Which is why removing the sender wire (open or infinity resistance) shows empty.

Possible... stuck float on the sender.

 

[Capt Tom]

Thanks to you all, I will try that. It probably wouldn't be a bad idea to pop the access plates and inspect to fuel tank connections anyway.

 

[Mad_Dog]

Hi Capt. Tom, I'm having the same issue. Was wondering if you ever got yours working and what the solution was?

 

[Halfhitch]

This is an old thread but Dennis's trouble shooting steps in post #3 above still apply. In 5 minutes you will have your answer.

 

[DennisG01]

Hi Capt. Tom, I'm having the same issue. Was wondering if you ever got yours working and what the solution was?

Welcome aboard, Dog. The same issue can have different causes. Take it step by step and diagnose. In the end, it's a very basic system with only a few parts to it.

 

[wspitler]

There is one other thing that hasn’t been mentioned here but it’s not likely to be the cause of your problem. The square Yamaha gauges have to be programmed for the type of sender. European versus USA. The resistance of the different sender protocols varies. If your Yamaha gauges are not correctly programmed they will not read properly. See the gauge manual for details.

 

[Beyond A Wake]

See all writing in my tank situation.
I would though add that it may be you are not using enough fuel for it to react from the point that was set as full when calibrated last.
It could have been calibrated for less fuel than full tank to show full.

H

 

[Hookup1]

These diagrams can help you troubleshoot the basics of the fuel gauges. Newer gauges may have a calibration but the level detection is the same.

A "full" gauge would mean a full tank, a stuck or bad sending unit or a open circuit. Burn off more fuel 1/4 tank or more. See if it starts working. It's not like your car - more of a guide - affected by boat attitude.

Standard sending unit range - 240 ohms empty to 35 ohms full. Unplug sending unit under deck plate - gauge should go to full.

How To Troubleshoot Your Marine Fuel Level Sender | KUS Americas, Inc.

Do you know what to do if your fuel level sender stops working out on the water? Click here to learn how to diagnose and replace a marine fuel level sender.

kus-usa.com

If you decide its the sending unit the KUS/WEMA sender are great. You need to know the length. Also be careful to "clock" the sender when installing - the holes are not symmetrically spaced and it matters!

 

[seasick]

These diagrams can help you troubleshoot the basics of the fuel gauges. Newer gauges may have a calibration but the level detection is the same.

A "full" gauge would mean a full tank, a stuck or bad sending unit or a open circuit. Burn off more fuel 1/4 tank or more. See if it starts working. It's not like your car - more of a guide - affected by boat attitude.

Standard sending unit range - 240 ohms empty to 35 ohms full. Unplug sending unit under deck plate - gauge should go to full.

View attachment 28851 View attachment 28852 View attachment 28853

How To Troubleshoot Your Marine Fuel Level Sender | KUS Americas, Inc.

Do you know what to do if your fuel level sender stops working out on the water? Click here to learn how to diagnose and replace a marine fuel level sender.

kus-usa.com

If you decide its the sending unit the KUS/WEMA sender are great. You need to know the length. Also be careful to "clock" the sender when installing - the holes are not symmetrically spaced and it matters!

Disconnecting the sender wire (pink) should cause an empty tank reading, not full

 

[Hookup1]

Disconnecting the sender wire (pink) should cause an empty tank reading, not full

That is what I thought but that article above says different.
“Disconnect the sending wire and the gauge should move immediately to “full”; if so, the gauge is not the source of the problem.”

 

[seasick]

That is what I thought but that article above says different.
“Disconnect the sending wire and the gauge should move immediately to “full”; if so, the gauge is not the source of the problem.”

It depends on where the article was originally published. In Europe the senders work in the opposite direction; Full is low ohms and empty is high ohms. Sort like driving on the other side of the road

 

[DennisG01]

Disconnecting the sender wire (pink) should cause an empty tank reading, not full

Correct.

See post #3