Ready heater 100,000 btu won't fire up!!!!!!!

Question

I't is a older model. there are no # to call. The fan and everything blows, but it acts like it is not getting any fuel or maybe the spark plug is bad. Someone has done allot of rewiring on this thing. I was hoping for some help or maybe someone can tell me where to find a repair manual, or parts book to fix it.

Thanks BN