1997 GMC Yukon Won't start

Welcome to the forum, if it cranks good but won't start, have a helper crank it, while you check for spark at the plugs. If you have spark everywhere, use a gage and check fuel pressure. Some of the national brand autostores used to loan fuel pressure gage. You can call and ask. They also have a spark tester. You pull a spark plug boot loose, stick tester in boot, a known good spark plug will work also. You ground tester or plug to metal part of engine, watch for spark as the engine is cranked.