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KennyO 
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Joined: October-19-2020 Location: Georgia Status: Offline Points: 31 |
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 Topic: Check Engine LightPosted: March-13-2021 at 7:53pm |
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I have a '99 Sport with 5.8 PCM and the "check engine" light is on. Temp indicates good on the gauge. The owner's manual says to take it to a shop. I don't know anything about this system but it doesn't appear to be the same as in a car. Can anyone help me with troubleshooting?
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1999 Sport Nautique
1988 2001 (sold) |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11093 |
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Posted: March-14-2021 at 7:18am |
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Assuming this 5.8 PCM is a GT40 fuel injected engine, it means that you have a system that right now thinks that you have either high coolant temperature of about 200 to 210 degrees or that you have low oil pressure of about 5 psi.
Either of these conditions should turn that light on and put the engine into "Slow Mode", often referred to as "Limp Mode" . How's the boat run, can you drive it at 3000 rpm with no issues or does it start cutting out at around 2700 rpm? Or maybe it's idling on the trailer and you don't know how it runs right now? If your oil pressure and coolant temp gauges say that you have normal readings for both, then you probably have a faulty oil pressure switch or coolant temperature switch. The switches are separate from the sending units for the gauges and can be unplugged for troubleshooting purposes if the gauges are reading normally. You could do a search on Slow Mode or Limp Mode here on CCF for info and look at the GT40 manual in the reference section.(it's the 310 page manual) Or answer the questions above and more help will be on the way  |
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KennyO
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Joined: October-19-2020 Location: Georgia Status: Offline Points: 31 |
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Posted: March-14-2021 at 7:30am |
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Thanks KENO.
It is not a GT-40 engine and it was running on the trailer. Have been doing an overhaul of the interior and haven’t put it in the water yet. So are all the questions applicable to the 351W also? |
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1999 Sport Nautique
1988 2001 (sold) |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11093 |
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Posted: March-14-2021 at 8:10am |
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Being a carbureted 351W means that you don't have to worry about things like Slow/Limp mode because you don't have a computer controlling the engine and you don't have to worry about that 310 page manual either
The dash light still tells you that you have either high coolant temperature or low oil pressure, but no protective functions of any kind come from the switches. If your oil and water indications are normal on the gauges, you're probably still dealing with a oil pressure switch or coolant temperature switch issue turning the light on. (bad switch) Not exactly being sure of a 99 351w wiring setup, I'd look for an oil pressure switch tee'd off of the oil pressure sending unit pipe and also a coolant temperature switch at the front of the intake manifold. Maybe somebody with a carbureted 351 in a SN, SN176 or Sport Nautique from those later years will have some info for you. As a guess I'd look for a green wire from each switch, as that's the color used on the GT40 engines |
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2001SAN
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Joined: June-26-2012 Location: Ireland Status: Offline Points: 246 |
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Posted: March-15-2021 at 3:50am |
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I helped a friend with the same engine and issue. Disconnected oil pressure switch as described above and light turned off.
Good luck! D |
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A little knowledge is a dangerous thing...
2001 Super Air Nautique 1989 Fairline Corniche 31 www.bannrivercruises.co.uk |
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KennyO
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Joined: October-19-2020 Location: Georgia Status: Offline Points: 31 |
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Posted: March-15-2021 at 12:10pm |
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Thanks KENO and 2001SAN.
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1999 Sport Nautique
1988 2001 (sold) |
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