Bought the boat over the summer with 200 hrs on it boat starts great cold pops right off also the boat runs perfect except when your running it and shut it down for 10 mins or so when I try to start it back up it starts hard don't just pop right off it idles real low then finally comes to also blows alittle black smoke any help would be great

Thanks josh

not knowing anything about the history the first thing I recommened is spark plugs ,cap and rotor,these engines run rich so start there,i bet that fixes it..

Check fuel pressure. If it has a fuel cool system the fuel pressure should be around 30 at 13 lbs or more of vacuum and around 40 under 13 lbs. If it's around 40 you have a bad fuel regulator. Common issue with these.

Already did cap and rotor plus new plugs still didn't fix it

easiest to do and a bad one won't always set a code is the IAC...Leaking injector/s could also cause your problem

check base timing

Iac valve was my first guess ill check more into the fuel regulator

Also check the iac muffler .They are a service item and will become completely stopped up. Just pull yours out and see if it changes things.It will be noisy

Technically you can't check base timing without putting the computer in mechanic mode. I have checked it multiple times and you will typically see around 12 without doing so at idle and warm.

All OEM marine engines go off serial # not so much year and model. Anyways anytime you bring a boat in for service the tech will or should run engine serial # to know what parts and what service manual to follow on repair procedures, with that said if your engine is a 2001 starting with serial 0M300000 and above - Mercruiser it will have ECM 555 computer control unit. The timing is NON ADJUSTABLE with all ECM 555 and PCM 555 and above computers, You can not adjust timing period even with a scan tool hooked up to the engine. Remapping is a different story but that is out most peoples hands on how to do so.

On all ECM 555 the rotor and the distributor have to be phased properly when it is pulled and reinstalled and of course the 496 and the newer 8.2 are distributorless. All Mercruiser MEFI computer engines the timing is adjustable. FYI. - IMO your problem is not timing at all. Also if your motor runs very rich and or is dumping fuel it could be the MAP sensor or of course a fuel delivery problem. - fuel injector(s) stuck open or fuel pressure regulator but you did mention any rich running conditions. I just threw that out for anyone else who has a MPI engine running rich especially at start ups.

Next IMO your problem sounds like a coolant temp sensor or connection in which can cause it to be out of range and or the IAC or its connection.

Always check connections first to be well connected, dry and very clean with not one spec of corrosion in the areas. Post your serial # of the engine so I know exactly what you have.

Next see if your motor starts in the clear flood mode - that is at full throttle - advance the throttle to 100% full give it a few seconds and see if it starts that way. Caution be very quick to pull back on the throttle if it does start.

Next it would be wise to get your engine scanned and see if any history codes have been stored plus any trouble codes that pull up. Anyways hope this helps and again engine serial # is the true way to know what the hell you have and how the motor is set up. ie: computer, ignition, fuel delivery, cooling set up and parts look up and so and so on for the jist here. Good luck,