I have a raised toilet (on a platform) with an electric pump in my basement. There is a sewer type smell when I open the lid. I am not sure what the problem could be and how to fix. Thanks!

Good morning Mooney,   ;D You have a holding tank and sewerage grinder pump installed right?  ??  First I would check the water level in the bowl.  This is a water seal that keeps the odor from coming back up the sewer pipe.  If it's low check the small 1/8" tube that runs from the top of the tank filler over to the white overflow tube.  ::)  This fills the bowl while the ballcock's filling.  There should be a strong stream going into the overflow tube.  Since you say the odor comes from inside the bowl when you lift the lid  :-[  and not from around the bowl itself I would pour 1/2 gallon of bleach in the bowl and let it set overnight.  :D  This should remove the odor if the water seal is intact.   ;) Cheers, Tom