Lb7 won't fire, electrical problem
 

I went to start my Lb7 on Saturday but would crank but not fire. Thought it would be something serious but we we're screwing around in the fuse box 2 days later and got it to start we don't know exactly what got it to start but we were trying to jump the f/pmp relay when it happens and we can't get it to start again. Any ideas please help.