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1995 GT 40 Running Rich |
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craigmeade 
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Joined: February-02-2020 Location: Florida Status: Offline Points: 25 |
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 Topic: 1995 GT 40 Running RichPosted: September-20-2023 at 12:18pm |
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Maintenance question for a 95 SN 195 with GT 40 engine. I am getting some unburned fuel out the exhaust, detected by the film on the water and exhaust smell. Changed plugs and ignition parts, still getting it. Boat is running great at idle and at speed. Thoughts on next things to check? |
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Jonny Quest
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Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2842 |
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Posted: September-20-2023 at 12:24pm |
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You may have a bad injector(s) supplying too much fuel. It's not too difficult to pull the intake manifold and remove the fuel rails and injectors. You can have them evaluated and cleaned if there is a local injector shop. Looking at fuel pressure regulator in conjunction with the injectors is a good place to start.
JQ
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 10650 |
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Posted: September-20-2023 at 8:06pm |
I'd probably start by reading that to myself a couple of times and saying "do I really want to screw with it?" I guess if you're seeing this film, it must be at idle speed, unless you're bloair charge temperaturewing smoke like a 56 Mercury outboard at all speeds. Have you cleaned the flame arrestor? They get ignored for years at a time and can get pretty dirty. Something like the coolant temperature being low will make it run rich all the time for example It could be low or a faulty ECT sensor could be telling the computer it's low. There's also an ACT sensor( air charge temperature) that'll make it run rich if it's defective, same with the MAP sensor (manifold absolute pressure) There are plenty of things to look at before just tearing into the injectors. Did the old plugs have black fluffy soot from running rich or were they normal looking brownish tan? Does it start good and after you turn it off and let it sit for 20 minutes or so does it start right up or crank like it's flooded? Have you checked your fuel pressure while running and watched it for a bleed down rate after you turn it off. That'll tell you something about the fuel system's health Run a bottle or 2 of your favorite snake oil like Seafoam, StaBil or whatever else through the next tank or 2 of gas if you think the injectors are dirty. So many questions, so many things to look at
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jhersey29
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Joined: February-20-2014 Location: Colorado Status: Offline Points: 272 |
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Posted: September-21-2023 at 12:06pm |
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"The positive crankcase ventilation valve releases exhaust gas and unburned fuel from the engine block into the intake manifold.
All engines allow some exhaust gases, unburned fuel and oil to “blow
by” the pistons and collect in the crankcase where it produces sludge if
not eliminated." - cars.com PCM part number R035023 Cheap and easy to replace. Usually if they are bad you would have signed of rough running but a bad one can contribute to a rich mixture and produce the results you are talking about.
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craigmeade
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Joined: February-02-2020 Location: Florida Status: Offline Points: 25 |
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Posted: September-21-2023 at 1:24pm |
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Thanks Keno and you are right, I have thought "why fix something that ain't broke" but I freeski in the bayous of NW FL so I have a soft spot for the dolphins I suppose....
Although i did not write it up the plugs looked normal upon replacement, although the cores had degraded and certainly needed replacing. I also cleaned the flame arrester. Thanks for the other tips and will come back on line if needed for an update, appreciate the help
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 10650 |
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Posted: September-22-2023 at 5:22am |
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Well, in that case..........be nice to the dolphins
Just lots of possibilities to work your way through |
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craigmeade wrote: