Maxxer 450i Fuel Gauge Stuck On FULL

[MaxxerManDan]

Hey guys. Newbie here. I have a '21 Maxxer 450 and took it out yesterday. The digital fuel gauge read "full" for the entire trip, despite how much gas was left in the tank. Does this sound like an easy fix? Any suggestions on a diagnosis? Thanks! -Dan

[Mech]

I'd check the gauges earth wire is ok..  And perhaps have a look into the tank to see if the float isn't somehow jammed upwards.. 

If you download the service manual  it will tell you exactly what to check and lead you through a step by step process to diagnose it.

[Mech]

So what was it, electrical or a stuck float ?

[Gwbarm]

Sounds like it might be electrical, not old enough to be badly gummed up gauge float. 

[MaxxerManDan]

This is gonna sound really stupid. After I took out the fuel pump and made sure nothing was sticking, I placed it back in and noticed the fuel gauge rising to "full" again (though the tank wasn't full). I repeated this process several times...same result. Then, I decided to syphon my tank till the level was a 1/3 full. Woolah! The gauge finally began to drop. Here's my takeaway...the "full" line on the tank is actually 3/4 to the top, and the gauge will read "full" until the gas level drops to about halfway.  Just seems really weird.

[Gwbarm]

I think that's the way a lot of them work, mine are older , that's the way they work , they are accurate when they point to E but not so much anywhere in between. Since yours is so new I thought the electronic ones may be more accurate.

[Mech]

Having to drain it down to only one third full before it shows any change doesn't sound good enough to me.

Some do, as you guys are saying, stay near full for a long time, but not I don't think to that degree.. That's not even a useful fuel gauge.. You'd have gone far too far out to make it back by the time the gauge even started to show any fuel used. That's just inviting trouble and worse than having no gauge.

Something in there might be bent or need adjusting somehow so it swings through a different arc and gets the full travel of the depth of the tank, or, the digital part of the gauge needs work surely ? They wouldn't have designed it that poorly.

I'd check that the gauge did range from empty to full with a full swing of the float's arm first, to be sure it's not an electrical problem. If it's not quite going from full to empty by a small amount, it might be possible to bend a stop on the arm, but watch the rheostat can travel that far. If it still doesn't go from full to empty it could be a bad earth on the tank unit or the dash.

then I'd measure the distance from the gauge's mount to the bottom of the tank, and to the full point of the tank, and then compare that to the floats distance traveled, and to the full and empty heights of the float. The float needs to travel through the right height distance, and through the right range. Sometimes putting a bend in the arm close to the pivot will get things right, and other times bending it right out near the end by the float helps. You might need to put two zig-zag bends in it so it shortens the arm, or straighten something to make the arm's effective length longer. First step is to get the float to travel the right distance up and down by adjusting the effective length of the arm, and then bend it again to get it to the right full or empty height, and it should read better than it is. If there is any need to compromise then do it so the empty reading is the more accurate one.

 

Edited March 8, 2023 by Mech

[MaxxerManDan]

Awesome advice, Mech! I'll have to wait until after my next ride in a couple weeks before I take the plastics off again, but I'll let ya know what I end up doing. Thanks for the help!

[Mech]

You're welcome..