Need help wiring new mower engine

[dinows]

I bought a new B+ S, 17.5 engine to replace my 18 HP blown engine on my Murrey rider. The installation went fine but when I plug the harness in it wont start. Need to leave it unplugged to run it, but it wont rev up nor can you idle it down and I think it has something to do with the electrical. There are 4 wires that come off the plug from the new engine BLACK<GREY<ORANGE AND RED The four colors from the plug that goes to the mower are GRAY< YELLOW, WHITE AND RED can somebody help. The Gray and Black wire that come off the mower go to the carb, but I dont know what the purpose is ??? but think that might be part of my problem. Thanks

 

[Rivets]

Is it possible for you to post pictures of all three plugs, new engine, old engine, and tractor? It would help us help you.

 

[dinows]

Thanks, will try and do that this afternoon

 

[reynoldston]

You will need some knowage about wireing. The last new B&S I installed in a John Deere I have to add a relay and a starter solenoid. Like said before maybe some pictures ?