Boats For Sale:
1995 Ski Nautique - Won't go above 1300 RPM |
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Khelms000 
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Joined: July-31-2021 Location: Austin, TX Status: Offline Points: 7 |
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 Topic: 1995 Ski Nautique - Won't go above 1300 RPMPosted: August-03-2021 at 8:30pm |
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Hi everyone! I recently found this forum while doing some searches about a problem I am having. I read a bunch of posts where others have experience problems with the electronic control limiting the engine RPM. It seemed that there are a number of things that could cause it. I recently was given a 1995 Ski Nautique Sport by a friend who hadn't used it in about two years. I hired a mechanic that cleaned the injectors, fuel rail, replaced the raw water filter housing, replaced the high pressure fuel pump, and put a 143 degree thermostat in it.
I took the boat out twice after he said it was good to use. Both times I was able to get on plane, but it wouldn't go over 2500 RPM. Both times it only went that fast for 5 or 10 minutes before it started to sound rough and about to stall. If I idled in gear it was fine, but wouldn't run over 1300 RPM. The 3rd I tried it, I could only idle and it would not go over about 1300 RPM unless it was in neutral. In neutral I can rev it up to 4000 RPM and it runs strong and sounds good. I did read about the SLOW function if the switches for the water temperature or oil pressure signal a problem to the ECA. I'm guessing that is what was happening the two times it got on plane, but didn't go over 2500 RPM. What could cause the engine to be limited to about 1300 RPM in gear and under load when it will runs great in neutral? The engine is the PCM GT40. The boat is a 1995, but I saw a 94 on the plate that has the model number. Thanks in advance for any suggestions. Kevin |
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Gary S
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Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Posted: August-03-2021 at 9:17pm |
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The easiest way to test this is to disconnect the 2 switches- they both have a tan/black wires going to them,I'll snap a picture in a bit. FYI fuel injected engines use a 160 thermostat as well.
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Khelms000
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Posted: August-03-2021 at 9:31pm |
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Thanks for the reply. I have been wondering if the 143 degree thermostat could be causing the problem.
Kevin
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gun-driver
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Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4112 |
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Posted: August-03-2021 at 9:40pm |
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I’m curious as to the high pressure fuel pump replacement as the ‘95 model pumps are like unicorns.
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Khelms000
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Posted: August-03-2021 at 9:45pm |
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I think the mechanic said he found one that would work. I don't think it was specific to this 95.
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Gary S
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Posted: August-03-2021 at 9:49pm |
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Oil pressure switch- the smaller of the two
 Water temp switch is in the water pump-  I would start by disconnecting the oil one first followed by the water if the oil one didn't help.
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Gary S
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Posted: August-03-2021 at 9:51pm |
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A picture of the pump he used would help.Thermostat would not cause your issues.
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gun-driver
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Posted: August-03-2021 at 9:55pm |
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Yes they are specific to the non fuel cell GT-40s. You can get around it with a different pump but you need to eliminate the cross over braided line to the return line. If that is still in place I would question if the pump was actually changed.
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Khelms000
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Posted: August-03-2021 at 9:59pm |
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Thanks Gary. The pictures are very helpful for me.
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Khelms000
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Posted: August-03-2021 at 10:02pm |
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I'm not sure I know where the fuel pump is or what to look for. I'll check it out when I am at the boat next time. Thanks, Kevin
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gun-driver
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Posted: August-04-2021 at 9:30am |
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The high pressure pump sit just above the low pressure pump. In this picture you can see the bottom of it behind the rubber exhaust tube. It’s the one with the one with the stainless braided line coming off the bottom of it.
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Gary S
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Posted: August-04-2021 at 6:09pm |
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Here is another fuel pump picture-
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Khelms000
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Posted: August-04-2021 at 7:22pm |
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Thanks Gun-Driver and Gary! You guys are awesome. Very helpful.
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Khelms000 wrote: