87 B2000 Won't Start, Help!

New to this forum. My son's 87 b2000 won't start. Battery is good but when you turn the key it has a single click on the right fender well under the hood. Is there a fuse, regulator or something that can go out?

new too and mine has igniton key problem know but i did have a starting problem 6mths ago which all would happen is i would turn key and it would click thats it noise sound came from passenger front...founf it had a warn bendix engagment lever inside head of starter found by pulling starter and solienoid after replaceing just the solenoid it still did the same thing so pulled apart started and there was a nylon lever that pushes bendix in and out that was worn so when you turn the key it click which was the bendix moving but not engaging(spinning to crank)