GM-GMC: chevrolet g 20 1990 van starting/running., starter solenoid, vacuum hose

Question
swapped out a 350 v8 with another. Does not seem to take the gas as I push the gas pedal and stalls out in reverse going over little humps. Today It back fired in the carb and quit running. The starter wont even attempt. Horn works, etc..but no starting attempt. I cannot find the vacuum hose layout anywhere. Have two manuals and neither is very helpful. It is a TPI controlled motor.

Thanks
Jim Denton

Answer
Need more information:  You describe a backfire through the carb but also that it is TPI, so which is it?.  How many miles on the engine?  Starting issues on GMs are usually traceable to the starter/solenoid assembly, battery connections, and the ignition switch, in that order.