After 3 hours of simmering my jam is still very soupy. How high should I have the temperature? Is there another fix?
Three hours is an incredibly long time for jam. Could you provide us more information? What did you include in addition to fruit and sugar (I'm assuming you added sugar)? Did you add pectin? Did you add liquid of any type? What fruit did you use?
Jam doesn't really set up until after it cools to room temp.
So, take it off the heat and let it cool. If it still is 'soupy' after that, no problem you can re-heat and add pectin, or some unflavored gelatin bloomed in water to the mix..simmer a bit again..and cool.
Needs to cool to from temp before it thickens