i have a 1991 Camaro RS V6 3.1 MPFI and it originally had the 91 engine in it but it had some problems so i bought the exact same engine except it was from a 90 Camaro but ever since i put it in i haven't been able to get power inside the vehicle to start it up, like no dash lights nothing, but if i take the starter wire and hook it directly to the battery everything lights up, i don't know whats the problem, i have a little idea it might be the computer but im not sure, can anyone help me it would be much appreciated, ive been trying to figure this out for months and im stuck.

 

what starter wire lights everything up? If you're talking about the main power wire that hooks to the starter solenoid with the battery cable, then there you go.

You have a bad connection with your battery cable or your grounding of your new engine.