T 100 won't fire up. Engine turns over. There is a clicking on top of motor

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. Fuel is rarely "bad" - so It would be very very unusual that fuel quality would be a concern. You replaced a fuel pump relay - but have you checked for fuel pressure with a manual gauge? A crucial diagnostic step. There is nothing to replace until you perform testing to learn if you are lacking fuel pressure, air to the intake or ignition spark. Check for these areas first and then proceed further with troubleshooting when you find out what direction to go into. Get help from a shop near you -- https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.