Fuel guage problems

[Tom1985]

Not sure if needed for this or not but I have engine s/n 3b042211 I have the sc1000 guages with my twin 200s I have a 190 gal fuel tank and have done the calibration by removing the sending unit from the fuel tank moving the float to each position because the tank is nearly full and pumping it out is not an option at this point..... the problem is it works right after its calibrated but seems to lose its calibration in the next day or 2 and back to being all over the place again.... turn the key on it reads 100% turn off back on roads 77% or maybe 50% then back to 100% or ect just all over the place this boat is 3-4 weeks old the dealer doesnt have a clue and they have another boat with same engines same make just a different model same hull doing the same thing they want me to agree to install a standard fuel guage I would rather not do that ....I looked over all the connections i can get to everything looks good to me not to say i couldn't have a bad connection but 2 boats doing the same leads me to believe its unlikely to just be a bad crimp or something.... im not sure if maybe having a battery switch being turned off and cutting power is causing it to lose its calibration..... the dealer does not have a mercury tech and the guys they do have I dont have much faith in... if taking to a different dealer was an option I would but the next dealer is 10 hrs away n this is a 30ft boat .....

[EuropeanAM]

First: Pulling the sending unit out and "manipulating" it as a manual calibration defeats the entire purpose. Might as well just reset it to "Default" calibration (which incidentally is often quite accurate).

Need to check and define each and every wire connection to the fuel tank. Grounds (colors), sender (colors), etc. Very important.

Hopefully just a sending unit that's on the blink (and not a wiring problem with the potential for electrical damage).