Epoxy will bond a little to ABS, but if it's molded chances are it's not ABS but PA/Nylon, PE, PP or POM, which Epoxy will bond very badly with. Close to not at all, actually. You could get a little mechanical bonding if you roughen the surface before gluing.
There are primers in existence that will give you better bonding to PE, PP or PA (nothing really helps with POM). These will not be available at your local marine
store though. You will need to find a specialized professional glue outfit. Devcon Flexane FL-20
or Sika 206 G+P
are not so bad in my experience. 3M Primer 94
is not as good, but better than nothing. (If you get them, be careful when working with isocyanate based stuff...)