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GT40 no power and wont plane out |
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SuperSport210 
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Joined: August-06-2020 Location: Nashville, TN Status: Offline Points: 6 |
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 Topic: GT40 no power and wont plane outPosted: August-06-2020 at 4:47pm |
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So short backstory is I bought a 1997 Super Sport 210 with the expectation that it needed an engine. It has sat for nearly 10 years under that assumption. I spent some time and determined the engine was good and the starter was just locked up. New freeze plugs and various other parts later I have a running boat.
Now for my problem, I cannot get it to accelerate past about 9mph and 3k RPM while in gear. It starts first try every time, idles well and will rev great in neutral. Also it seems to have descent pull in reverse but I usually wouldn't do more that 3k RPM in reverse anyway. I have replaced both fuel pumps, regulator, fuel filter and of course siphoned 10 year old fuel from tank. Normal ignition components are new also. Cap, rotor, coil, plugs, wires and even the distributor.. I have also checked and set timing. I have tried running it with the oil and water temp switches disconnected to rule out limp mode and saw no change. There was no check engine (assuming the bulb isn't burned out.) The light that says not to operate if it stays on over 1200 RPM goes out at 1200 like it should. I'm running out of ideas. My next plan is to test fuel pressure and I ordered a code reader today to see if that gives me any leads. Any other tips or tricks would be greatly appreciated.
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1997 Super Sport
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Mpost
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Joined: July-05-2018 Location: Monticello, MN Status: Offline Points: 330 |
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Posted: August-06-2020 at 6:55pm |
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Your comment- "There was no check engine (assuming the bulb isn't burned out.) "
You should not have to assume the CEL is good. When you turn the key to the on position the CEL should come on. When the engine starts and you have oil pressure the light will go out. |
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84 SN Sold 98 SN Lund Pro V 1975 Alumacraft
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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-06-2020 at 11:03pm |
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If your serious about the 10 year old gas I wonder if you have any injectors that are not working properly? That would certainly not set off the limp mode,but might act like that I'm thinking. Be real careful trying it to run hard don't want to be melting a piston or something. If you find out they are the problem sometimes you can have them cleaned professionally or look for some new brand name 24 lb injectors. Ford Motorsport ones can be had starting around 200. There is no thing as marine injectors.
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MrMcD
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3750 |
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Posted: August-07-2020 at 12:01am |
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I would run it with a fuel pressure gauge installed and see what happens as you try to accelerate. I don't have the exact numbers on hand but it should be 39-46 or something like that. If you pressure drops off as you accelerate you know where to look to fix it. If the pressure goes up a little as you accelerate it is fine. Someone will jump in with the exact pressure needed.
There is an anti siphon valve at the fuel tank that might be cutting off fuel flow but I would check pressure and verify before chasing anything else. It is mandatory on a Fuel Injected engine to perform correctly. Mark
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slmskrs
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Joined: January-03-2012 Location: SF bay area, CA Status: Offline Points: 522 |
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Posted: August-07-2020 at 2:03am |
This is not making sense to me. There's no way the boat at 3kRPM is only going to go 9mph unless you have prop slippage (tranny issue). 3kRPM should be somewhere around +/-30mph. There is a gear press-fit into a bell housing in the PCM 1.23/1 tranny. On my '96 it just worked itself loose over time. I pulled the tranny apart not knowing that it was supposed to be press fit (tight) since it slid. When I showed it to a boat tranny repair shop, they said that was the problem. Plenty of RPM, but slipping (it did make some noise). Wasn't worth the hassle to try to rebuild (I was paranoid I'd screw something up and I didn't have tools to press bearings, etc.), so I just opted to get a new one from SKIDIM. That's a $2,500 replacement, so maybe your issue is something that's less expensive. But unless I missed something about the 9mph @ 3kRPM, your prop/tranny is slipping. BTW, the replacement tranny from SKIDIM is a model 80 (replaces the 40). A tad bigger, but fits fine. Also, comes with new damper plate, AND a 12" tranny cooler (twice the size of the original). When I got my '97 project boat and sold my '96, the first thing I got (okay, along with new steering, shift, throttle cables, and Stargazer) was a 12" cooler to replace the original 6".
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Gordon '97 Ski Nautique, GT40
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SuperSport210
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Joined: August-06-2020 Location: Nashville, TN Status: Offline Points: 6 |
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Posted: August-07-2020 at 8:55am |
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Good tip on the CEL. Ill keep that in mind and check that circuit.
Fuel pressure is my plan for this weekend, I have yet to look at that anit-siphon but its at the top of my list depending on results of my pressure test. Now for the possible transmission slip... That has crossed my mind but the thing that keeps me from chasing it is that the boat just stops revving at roughly 3k. If it was the trans I would think it would keep revving to limiter. Please correct me if I'm wrong. It is also very slow to reach "max rpm" so I think that's why its not faster at that rpm. Thanks for input, I'll update with my fuel pressure results soon.
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1997 Super Sport
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RealDeez
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Joined: August-01-2019 Location: MI/IN Status: Offline Points: 131 |
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Posted: August-07-2020 at 9:26am |
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Video might help. I'm with the folks thinking about the transmission/ prop. Unless you filled the bilge with concrete and are towing a 40' yacht there's no way the engine is turning 3k and you're going 9mph.
You sure the tachometer is working? |
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Lake James, IN
93 Sport Nautique |
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slmskrs
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Joined: January-03-2012 Location: SF bay area, CA Status: Offline Points: 522 |
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Posted: August-09-2020 at 2:18am |
Agree 100% (great visual BTW  ). Also, even if the engine just won't go past 3000rpm, the boat has to go faster than 9mph unless there is something seriously wrong with the prop or you have slippage. If I go in gear and slowly raise the rpm's, I'll be planning well before 2000rpm (haven't checked, but pretty sure it is in the 1200-1300rpm range. Even if I did it really slowly, the boat is going to plane regardless.Really good point about the tach. My '96 tach got spastic and sometimes would show 4krpm when it was at 2,000. Othertimes it was fine. My '96 project boat has the same problem. Fixed it by turning the #cylinders dial switch a few times. So really good idea to make sure your tach is reading correctly.
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Gordon '97 Ski Nautique, GT40
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SuperSport210
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Posted: August-09-2020 at 9:04am |
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So I checked the RPM and fuel pressure. Using a timing light with rpm display I’m seeing more like 1500 rpm. As for fuel pressure it cranks and idles at 35psi and as I rev or accelerate it goes up to about 42.
So I’m still trying to wrap my mind around the idea of a slipping trans... Slipping would make me think I would still be able to reach max rpm but wouldn’t have any speed, like a slipping clutch in a car. This thing is acting more like there’s too much resistance in the drivetrain. Is there a way to check the trans or vdrive? |
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1997 Super Sport
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MrMcD
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3750 |
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Posted: August-09-2020 at 10:56am |
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Engine off, you should be able to rotate your prop by hand. I would start there. If it has high resistance that would cause heat at the problem part, v drive, strut or Tranny when operated.
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8122pbrainard
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Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Posted: August-09-2020 at 11:00am |
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Curtis,
While you're down there turning the prop, see if you can see what prop is on the boat. However,you may need to pull the prop since the specs are typically on the end of the hub.
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SuperSport210
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Posted: August-12-2020 at 8:32pm |
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Ok finally got to check the prop. I am able to turn the prop by hand. It seems normal to me but just to double check, when turning it will not free spin; I do have to keep pushing to make it turn but not much force is required.
Also it is an acme 816 13.5 x 17.5. The edges seems somewhat rolled over upon closer inspection I did find a few slight bends. Doesn’t seem bad enough to be causing my problems but still probably worth replacing. |
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1997 Super Sport
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GottaSki
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Joined: April-21-2005 Location: NE CT Status: Offline Points: 3363 |
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Posted: August-12-2020 at 9:22pm |
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You need a new prop
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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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-12-2020 at 9:48pm |
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V drives won't spin the prop by hand like a straight will- awful lot of hardware to turn. On that note I think you are over propped you need something like a Acme 380 or 644. A 816 has alot of cup and who knows what it is if it's bent up
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slmskrs
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Joined: January-03-2012 Location: SF bay area, CA Status: Offline Points: 522 |
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Posted: August-13-2020 at 1:09am |
Okay, first, it will not free spin; it does take a little effort to turn (when dry on the trailer), but it sounds like yours is about right. If you pull it out of the water and spin it, it will spin easier. It does sounds like a new prop is appropriate. However, I have to go back to 1500 RPM max. Since there doesn't seem to be excessive resistance, I think we need to do a few more tests on the tranny, and then turn back to the engine. First, what are your RPMs out of the water (fake-a-lake, etc.)? Or, pull the prop and then drop it in the water and start and run. If you goose it, does it race up to 5k, or lug? Also, with it out of the water (or in the water with the prop off), is there any difference between raising the throttle in neutral vs in forward? I'm going to assume that it's going to be just about the same in neutral or in gear, but sluggish / even in neutral/out of water, which would point back to the engine. Let us know.
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Gordon '97 Ski Nautique, GT40
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SuperSport210
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Posted: August-13-2020 at 8:35am |
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When revving in neutral it will get up to 5k quickly and seems healthy. Its only when putting it in gear that things seem to be off. A friend suggested I disconnect the prop shaft at the V-drive and test it in gear like that so that was my plan in the coming days.
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1997 Super Sport
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slmskrs
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Joined: January-03-2012 Location: SF bay area, CA Status: Offline Points: 522 |
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Posted: September-23-2020 at 9:47pm |
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Hey SuperSport210, any update?
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Gordon '97 Ski Nautique, GT40
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SuperSport210 wrote: