93 Plymouth laser 1.8 will crank but not start, Help!?

The motor will crank and crank but doesn't fire everything seems okay. We changed distributors that didn,t work, checked timing, check fusible links, and all the basic but it still won't turnover. A friend said it may be a porcelin fuse on the firewall causing the problem but haven't been able to locate the thing. Any suggestions would be greatly appreciated!