Can anyone help please , I have just bought a CF 450 L Quad , when the fuel tank is full the fuel gauge does read full and will gradually drop as fuel is used , BUT when the tank is well over half full the gauge will suddenly show empty and starts to flash even though there is around 10 litres of fuel in the tank , I have have fitted a new fuel level sensor but the same problem still exists , any suggestions / help would be much appreciated , thank you.

Anybody out there can help ? Please !!!!!!!!!

[2015 Z Force 800 53/Trail EPS]

This would normally suggest the level sensor is bad..even the new one. Looking at the 400's wiring diagram the level indicator gets it's power from the dash/pod and it's ground through the tank sensor. Grounds to the same circuit as the tail lights so..are all the tail lights working? If not it could mean a bad ground or connector in that area. If not the sensor or the ground then it would suggest a pod/dash electrical problem.

I thank you for your help , everything else is functioning correctly ie Tail lights etc , I did connect and operated the new level sensor before inserting it in the fuel tank and it read perfectly throughout the range of the fuel gauge ( all the bars on the gauge ) , really weird one , just wish I could get to the bottom of this annoying problem Grrrrrrr 

I'm not trying to tell you that this is normal... but I have a 500s and a 400. Both show fuel usage to be a lot faster than it really is. The 400 is the worst one. I can fill the tank and ride for a few hours at an ATV park. Last trip we all rode in a line, the same trails, same hills, same speed and both 4 wheelers only had one rider around 170-185 lbs.
Once we got home and I was unloading, the 500s showed about 3/4 tank of fuel left. The 400 showed around a 1/4 tank. I opened the tank and looked in to find that both had about the same amount of fuel, right around a 1/2-3/4 tank. We rode about 30 miles that day.

[2015 Z Force 800 53/Trail EPS]

Fuel level monitoring isn't one of CFM's strong points. Even my 2015 Z..below 1/2 tank it's anyone's guess. I tend to watch the miles on the trip meter when it gets below a certain point over the gauge.

Thank you all for your comments , looks as though I'm going to have to put up with it 

[2015 Z Force 800 53/Trail EPS]

Thank you all for your comments , looks as though I'm going to have to put up with it 

I personally think if it's not the sending unit it has to be the gauge itself. The sending unit is just a potentiometer varying the degree of ground connection and most likely the first thing to go bad...but with so many having the same issues and with no change happening by replacing them, I have to think the dash's electronics on the gauge has to be the real issue with some of these. If yours is still under warranty I would make them change the pod/dash out.

Thanks for your comments , I did connect and test the new level sensor throughout it's range before inserting it in the fuel tank and it did appear to show correctly , all the bars on the gauge did operate as they should , weird