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Engine Depositing Carbon via Exhaust
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Author:  Roger B [ Tue Nov 18, 2008 9:14 am ]
Post subject:  Engine Depositing Carbon via Exhaust
8) The marine engineers have just winterised (I am UK based) my 1997/98 258 Vista and they have reported that the Engine is depositing carbon via the exhaust upon start-up (it's smoking!). It's an OMC branded engine 5.7 FCPBYC (Volvo Penta equivalent for 1998 is 5.7 GSI PBYCCE). Do you guy's have an idea as to what my problem might be? Many Thanks, Rog.

:arrow: Hi Gordon/Walt B
Yes, it is running too rich at cold-start - clouds of black smoke. Once warm it runs fine. Plugs are very black and sooty. It's carb rather than FI.

Thanks for your help guy's - Four Winns are not very common here but I am flying the flag!
Author:  M3eater [ Tue Nov 18, 2008 5:02 pm ]
Post subject:  Re: Engine Depositing Carbon via Exhaust
Rog,

A little more info is needed. Just what do they mean by "depositing carbon"?

Is it running too rich at cold-start?

Can you get some more detail?
Author:  Walt [ Tue Nov 18, 2008 5:39 pm ]
Post subject:  Re: Engine Depositing Carbon via Exhaust
Is this Carb or FI? On start up only?

Carb could be T-stat in carb that determines if the engine is in cold start, or hot start condition. I've seen this on a '92 Crown w/ Merc 350 before. It smoked like a Crack addict at idle, and didn't handle hot-start too well. Sucked for Skiing/Tubing, etc.

FI could be related to engine temp sensor/ Abs Press Sensor. Seen this on my last EFI truck.

Good luck!
Author:  M3eater [ Wed Nov 19, 2008 12:50 pm ]
Post subject:  Re: Engine Depositing Carbon via Exhaust
On the carbureted engine, the choke it likely closing too much AND not opening as it should, as the engine warms up.

It's likely an electrically heated choke housing that heats a bi-metal spring which pulls the choke plate open as the spring heats up. The electric choke housing will have power to it whenever the ignition is on. A first check is to see if there is power on the choke power wire. Pull the wire off of the choke housing and test for 12-volts (or use a test light), from the wire to ground, with the ignition key in the RUN position.

Sample 4-bbl Rochester carb with electric choke. Choke housing is on the left in the photo. If you have a 2-bbl, it will look different, but the choke housing will be similar.

Image

Let us know what you find, and we can go from there.
Author:  ht32bsx115 [ Sat Nov 22, 2008 1:16 pm ]
Post subject:  Re: Engine Depositing Carbon via Exhaust
Roger B wrote:
8) The marine engineers have just winterised (I am UK based) my 1997/98 258 Vista and they have reported that the Engine is depositing carbon via the exhaust upon start-up (it's smoking!). It's an OMC branded engine 5.7 FCPBYC (Volvo Penta equivalent for 1998 is 5.7 GSI PBYCCE). Do you guy's have an idea as to what my problem might be? Many Thanks, Rog.

:arrow: Hi Gordon/Walt B
Yes, it is running too rich at cold-start - clouds of black smoke. Once warm it runs fine. Plugs are very black and sooty. It's carb rather than FI.

Thanks for your help guy's - Four Winns are not very common here but I am flying the flag!



Howdy,

Here's your carb based on the model number you provided.

http://www.volvopentastore.com/CARBURET ... _id.312935

Those "Marine Engineers" should have no problem readjusting the electric choke on your carburetor.

The electric choke mechanism is simply an electrically heated (time dependent) device that will open your choke after it heats up. The time it takes can (or should be) adjusted to be roughly equivalent to the time it takes for the engine to warm up enough to not need it. If you live and/or operate in warm weather you really don't need very much "choke" for starting. (I disconnected my electric choke altogether) If you operate in cool weather a lot you'll need a little more. Since it's adjustable, you (or your Marine Engineers) can experiment with a setting that works best for your climate.


Since that's a 98 model, it may also just need to be rebuilt or replaced. That link above also has the part number for a repair (rebuild) kit.


Regards,
Author:  Roger B [ Fri Nov 28, 2008 9:11 am ]
Post subject:  Re: Engine Depositing Carbon via Exhaust
:D Thanks for all your help Gordon, Walt B and Rick. I am following up on the faulty electric choke.

I should be making less smoke on start-up next season thanks to you guy's. Winter is setting in here now and because I am on the River Thames and we get high water levels, I won't be out again until early April.

Happy Boating,
Regards Roger
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