Hell no! That's like asking are all skinny chicks a bad lay. You can't generalise like that.

Being overweight can contribute physically and mentally - but it isn't an indicator.

Best thing is for your husband, if he is willing, to go have a full check up and for him to tell the doc he's having ED issues. The doc will take it from there. As for you, see if you can involve him in your orgasm some way that doesn't require him to have an erection. Does he perfrom oral sex on you? Does he play with your g-spot? Will he play with a dildo or vibe with you? There's lots of ways of having sex without an erect penis - ask a lesbian.