Twin 225 SWS both smoke at idle after warmup

[finncrossing]

I have a 1997 Grady White 272 w/ twin Yamaha SWS. I use ring free and have an excellent mechanic. I keep up w/ maintenance each year. Both engines run sweet, but I have a problem which my mechanic tells me not to worry about. When the engines are cold and have sat for a several days, they smoke at startup, as expected. But as they warm up, the smoking get's worse. Also, this applies to both engines. It's especially bad after I shut down, and restart the engines, even the next day.

Don't notice anything unusual at high RPMs. and both engines seem to use the same amount of oil, though I have not really measured to the point that I could say it averages 50:1.

I know they are 11 years old, and maybe I'll have to live with it, but it's uncomfortable when I see the reaction of people on the dock.

Is there somthing I can do to reduce the smoke at idle on both of these engines.

Thanks so much

 

[rodbolt]

Re: Twin 225 SWS both smoke at idle after warmup

can ya post the full model number as the 225 in 1997 was made in both a 3.1L and a 2.6L with vastly different ign and fuel controls.

 

[finncrossing]

Re: Twin 225 SWS both smoke at idle after warmup

Hi Rodbolt;

Thanks so much for the fast response. I'm at my office so I'll have to go down to the slip after work for the info. The Serial numbers (from my original survey) are 100103 and 100134. They list the model as a SWS II V225-76. They have the O2 sensors so I guess that means they are OX66. Can't remember if they are EFI or HPDI.
I'll check out the engines tonight and get back to you.....

Thanks again

 

[finncrossing]

Re: Twin 225 SWS both smoke at idle after warmup

Hi Rodbolt;

This is whhat I got off the engine (port) tag this morning

62K L225TXRV

Hope this helps

 

[finncrossing]

Re: Twin 225 SWS both smoke at idle after warmup

Hi Rodbolt;

One more comment. I have had the VST tank serviced and a new inline 10 micron installed on both engines this year. The O2's have not been services in the past three years (that's how long I have owned this boat) but mmy mechanic does not agree this is the problem. I was wondering, the low pressure lift pumps have not been changed, and as I understand it, they should be changed every three years.

Anny thoughts....

Thanks

 

[rodbolt]

Re: Twin 225 SWS both smoke at idle after warmup

ok, they are 3.1L v6 yamahas that incorperate a CCS ign/fuel system.
means #2 and #5 are shut down between 800 and 2000RPM.
your way past due for O2 sensor cleaning/TESTING.
note the shouting of TESTING??
occasionally we see oil pump shaft seals fail but first I would carefully check the linkage adjustments paying careful attention to throttle fully closed does NOT mean idle speed it means the link on the lower two shutters dissconected to allow the lower shutter to FULLY close.
that system actually mixs the oil and gas in the VST so some smoking after prolonged sitting can occur due to the gasoline can evaporate and leave excess oil behind.
on the lift pumps,yes the 3.1L motors are rather tough on them. Yamaha makes no reccomendation, its mine and based on 15 years or so of working on the 3.1L motors.
pop a diaphram and not only will the engine idle poorly and maybe not quite to top RPM but the raw fuel entering the crankcase can lean out the oil mix and trash a rod or piston.
never a good thing.
but most anything ya wish to know about it feel free to ask, just dont PM me

 

[finncrossing]

Re: Twin 225 SWS both smoke at idle after warmup

Rodbolt;

Hope you had a great weekend, and thanks so much for the response. I'm going to take your advice and bring the outboards up to spec. I've purchased 6 new low pressure fuel pums and will replace them this week. Waiting on order for factory maintenance manual from dealer (Tri-State Marine). Once I get the manual, will go thru throttle adjustments and also check the O2's .

BTW, if you do respond to this before I receive the manual, should you remove the VST tak to change the low pressure fuel pumps. One of the three is behind the tank, and it looks like the pump can be pulled ok, but the fuel lines look a little crowded and migh be diffficult to reinsert after the pumps removed.

Anyway...thanks again and I'll post my progress

 

[rodbolt]

Re: Twin 225 SWS both smoke at idle after warmup

the easiest way to access the lift pumps on that engine is by removing the screws holding the VST to the block.
be aware the back-up washers will fall and you have to retrieve them.
make sure the O2 sensors get tested as per the 3 tech bullitens disregaurding the flame test one.