'95 Ski GT-40 question |
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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Posted: April-30-2015 at 3:16pm |
Hey gang!
Our new to us 95 Ski seems to be, for lack of better term, "chugging" at WOT. The best way I can describe it is compared to a carbed motor not all 4 barrels opening up. It's up around 42-43mph at 4600 rpm running a 654 ACME 12.5X15. It's right there, but feels just a tiny tiny bit short of what it should be. I'd assume the basics..plugs/wires (not sure when those were done last) but didn't know if you guys had any secrets on these GT's. Fuel could also be to blame I suppose. Haven't run a fresh brand new tank all the way through yet this year. |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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I think Zach has mentioned before that the caps and rotor can have issues, so change that too.
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Fl Inboards
Grand Poobah Joined: January-20-2008 Location: United States Status: Offline Points: 2099 |
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what rpm's are you running when starts to chug ?
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Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.
1993 Shamrock "fat" 20. 2008 Nautique 196 5.0 |
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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4600 RPM. When it's not chugging or trying to open up itll bump up to 4700 and I think it wants to do 4800 but won't get there.
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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Come back after you get a few gallons of fresh gas through it. Certainly wouldn't hurt to inspect the cap & rotor. |
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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We have practice tomorrow night and Sat AM so we'll run a bunch through it then and I can report back. I'd assume that's what's up...or hope anyways :)
I know the GT's had a little thing about the chug situation I guess so thought I'd check. And I'm bored at work and like to talk about Nautiques |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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That early gt40 in that hull should pull a 654 to 5200 and at least 46mph. You're a good ways off those numbers, something's up.
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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woah...I was wondering what top RPM should be, Tim. Is that safe to run 5200? If it ever got there? Can't remember what the desired top is on those. If that's the case...then yes I'd say something is up. |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3734 |
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I would change the fuel filter or filters if this boat is new to you and you don't have the history. If you are going to run it and burn through a tank of fuel I like to add a quart of automatic Transmission fluid to the fuel tank. ATF has many cleaning and lubricating properties that help clean a fuel injection system. It keeps the injectors snapping the way they should. I only do this once per season.
You might wish to put a fuel pressure gauge on it when you run it and see how the pressure is holding up when your power falls off. The 95 has a temp sender and an oil pressure sender that can put your engine into limp mode if they go off at the wrong time. My coolant sender started making my engine stumble when the raw water pump was not putting out enough water to keep the temp constant. I guess I should be appreciative since I was able to fix it with no damage done. I run a Acme 224 Prop and RPM above 5,000 RPM and top speed of 48. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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My thoughts exactly with a 654 |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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4800-5000 is optimal for best all around performance but 5200 won't hurt it.
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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Thanks guys! I was wondering what top RPM should be on that thing.
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3734 |
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When the GT40 is running good it is pretty impressive for a stock engine.
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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I've always been a fan of the GT40's. Seems so strong.
Mark, side note, your boat and trailer combo is in my top 5 Nautique favorites. You can't beat red black and white on the water. |
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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Hey Mark, you say you run a 224 prop. We run a 1442 on our Sport Nautique and the tranny knocks or dampener plate makes a little tick at idle with that thing. Does the 224 do that to you?
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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The tick is caused by the damper being worn or the idle needs to be adjusted, even if it only shows up with a particular prop, it is not the true cause.
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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Interesting...Sporty only has about 140 hours on it! Doesn't do that on any other prop was kind of my thinking.. |
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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The bigger diameter of the 1442 combined with the high pitch could be just loading the drivetrain enough to lower the RPM and then rattle.
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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This is what I've been told in the past, HW. That 224 has even more pitch than the 1442 so that's why I asked about it. |
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Fl Inboards
Grand Poobah Joined: January-20-2008 Location: United States Status: Offline Points: 2099 |
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In the mid 90's we had some 3/8" fuel hose that the inner liner tended to collapse on the suction side of the fuel delivery system. If it has it's original fuel lines in it I would be prone to go completely through the fuel system from the pick up tube and anti siphon fitting forward, inspecting and changing out the original fuel supply and return hoses, and checking that the vent hose was clear as well as the vent. along with a quick tear down of both fuel pumps, especially the low pressure pump as gradew seems to accumulate in the screen in the top of the pump.
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Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.
1993 Shamrock "fat" 20. 2008 Nautique 196 5.0 |
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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You're killin me Jody. hahahaha Thanks for that, I think |
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lewy2001
Grand Poobah Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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Fuel pressure check.......
The early 95 GT40 without the FCC should still have a "Schrader" valve on fuel rail. |
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If you're going through hell, keep going
89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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On a side note Mark, Skidim is listing new for '15, PCM ECM's for all GT40 efi engines at $572.69
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Toertel
Gold Member Joined: August-26-2013 Location: Atlanta Status: Offline Points: 775 |
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Since we have a GT-40 in the Sport I'm following this post in order to be potentially prepared if things go south. Is the ATF idea good? Thoughts ? Sorry to jump off topic but this. caught my attention |
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1994 Sport Nautique
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mdvalant
Grand Poobah Joined: May-06-2009 Location: Bellevue, IA Status: Offline Points: 2059 |
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I too was wondering what everyone's thoughts were on the ATF idea.
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lewy2001
Grand Poobah Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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I had a lot of fun with my ECM project for the GT40. I started it thinking that down the road I may build a stroker engine. I run the DIYPNP ECM all the time now and I am continually analysing and updating the tuning. |
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If you're going through hell, keep going
89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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I would rather see Marvel Mystery added to the gas than ATF. Both are very similar with being heavy on detergents but the Marvel is designed as a top cylinder lube. The ATF is more on the hydraulic oil side.
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Toertel
Gold Member Joined: August-26-2013 Location: Atlanta Status: Offline Points: 775 |
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Thanks Peter! So if I would consider doing it, then with Marvel, but is this needed or a preventative thing to do? Saw this come up theb1st time in this post.
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1994 Sport Nautique
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JoeinNY
Grand Poobah Joined: October-19-2005 Location: United States Status: Offline Points: 5698 |
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Fuel injector cleaner costs about the same as atf last I checked.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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I've heard of guys running ATF and Jet-A in diesels for clean up but not in gassers doesn't mean it can't be done just never heard of it till now.
As for the GT -40 I run the 1442 runs 48 - 49 and will spin it up to 5200 and I'll run It there for a long time getting down the lake. Won't hurt a healthy 351 |
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