Hey guys, I have a 1990 OMC Cobra 4.3L with brand new 2BBL holley carb. and a brand new electronic delco voyager distributor with a brand new fuel pump as well with new spark plugs. Here is my problem, I took my boat out and everything was running good on my first 4 tanks of gas. Approximately 25 hrs or possibly more. Now after running while the motor is very hard to start after running around for awhile. Whenever the engine warms up in takes quite a bit of cranking over to finally get it to fire up and start again. Black smoke comes out of the back of my boat when getting started. I am noticing that oil is coming out of the breathers going to the carb. Not a whole lot but the cover on top of my carb is slighty oily. I notice from draining my oil from last 50 hrs that it was a quart short of what I put in there. What can be the cause of this hard starting now after there was no problems a couple of days right before my engine started doing this. Any help to check would be awesome! Thanks guys