Black exhaust stains on hull

"Hi,
I have recently aquired

"Hi,
I have recently aquired a 2003 bayliner ciera 245 with a 5.7litre merc bravo 3.
I had to purchaes it sight unseen.
I have had it in the water twice and both times it is smokey on start up although that clears up when it warms up.
When i take it out of the water there is a black sooty line along the stern under the swim grid that extends up the port side at the waterline.
Does anyone have any ideas.My worry of course is bad compression and my hope is that it is normal or maybe it just needs a tuneup.
Any advice would be appreciated.
Thanks."

I suspect your choke. Look at

I suspect your choke. Look at the top of the carb just after startup when the engine is running rough and let us know if it smoothes out when you manually push open the choke butterfly valve.

"Ross,
I agree with MistaH

"Ross,
I agree with MistaHays.That would be my guess also.It is not that expensive to do a tune-up especially since you just purchased the boat and it will sure give you piece of mind that you are starting out running ok and have physically seen each plug to know how each cylinder is running.Change some filters and a few other maintenance things and go enjoy your investment.....Todd"

"Thanks for the replies,
The

"Thanks for the replies,
The boat is an hour away form me so it will be a couple of weeks until I can do that test.
I will do the plugs and fuel filter also.
The motor only has 130 hrs.Do you guys think I can rule out low compression?
If it is the choke do I need to have a mechanic look at it or is it a "read the manual" fix?"

"Ross
Read your manual and yo

"Ross
Read your manual and you will be fine Mr Hays has probably nailed it, sounds like a choke problem to me if it is a carburettor engine and not an EFI.
Cheers
Peter C"

"The remedy if it is a choke i

"The remedy if it is a choke issue is to test to make sure the "choke pull off" is working properly. If it is, you may be able to solve with a slight adjustment to the choke spring.

The choke spring closes the choke valve to a predetermined gap during cold starts and then retracts it gradually as the engine warms up.

Some pull off's are vacuum acutated and some with electricly heated elements as i recall. The last mercruiser i diagnosed with this symptom had an electric choke heater that was not getting power.

From my car experience, I seldom use the words "tune up" these days. It used to mean something when all engines had breaker point ignition but now it just means plugs, filters, oil change and a good look over. When said, customers think they are getting somethign but it seldom solves running problems.

Pete - it's 32 degrees F here in Washington DC. Hope you are enjoying the season down under because I'm not! An old scotch, a fresh cigar and a boat mag will have to do for me.

Hays"

"Hays
The weather has been cr

"Hays
The weather has been crap here all this week anyway so dont worry about it, my boat wont be leaving the mooring this weekend.
We are having an unusual summer season this year, at this time of year we would normaly be fairly consistant around the 26-30 degree C here but this morning it was 16, a wee bit chilly.
Never mind, I have to do some work on the family holiday cabin this weekend so that will keep me entertained, I may have a couple of scotch's but you can have the cigar.
Cheers
Peter C"