GT-40 bogs/lacks top end speed |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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Posted: July-26-2011 at 5:39pm |
Hi, new to the site and unfortunately have a problem with my 96 ski nautique, hoping someone has experienced this issue and can help. Initially, while running at ski speed the boat would hesitate, slow down, then recover. Then it started doing something a bit different, fairly strong out of the hole, get up to speed at ok rate then take off suddenly(engine running strong) so I have to back off on throttle. NOW it is sluggish out of the hole, and won't get up over 36mph (4500rpm) at full throttle. I picked up a fuel pump relay switch and new fuel filter but have yet to try the boat. Any tips or fixes would be greatly appreciated!!!!
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M3Fan
Grand Poobah Joined: October-22-2005 Location: United States Status: Offline Points: 3185 |
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Start with measuring your fuel pressure off the rail using a fuel pressure gauge.
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2000 SN GT40 w/99 Graphics/Gel
2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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ok, i will check that out first, thanks.
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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it was 42psi at idle and at full throttle.
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Luchog
Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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have you checked the antisyphon valve?
I'd check fuel pressure at both pumps, clearly if you have 42psi your high pressure pump is working, what about the low pressure one? engine story? hours? oil pressure? |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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Thanks for the help guys....it was the fuel pickup screen at the fuel pump. It was half full of crud, I cleaned it out and my baby runs like a rocket now!! Thanks again everyone :)
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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scooter t
Newbie Joined: 18-September-2010 Location: Moncks Corner Online Status: Online Posts: 4 Post Options Quote Reply Posted: Today at 12:50pm Hey, I have a 95 with the GT40 and have been experiencing surges in speeds for several months now. I would like to check the screen on the fuel pump to see if thats my culprit. Can you tell me in detail how you did that and where its located. Sorry....i'm just a skier....not much on motors. Any help would be appreciated. |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Shawn,
The screen is at the bottom of the fuel line dip tube that's in the fuel tank and the anti-siphon valve is in the 90 degree fitting at the top. |
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M3Fan
Grand Poobah Joined: October-22-2005 Location: United States Status: Offline Points: 3185 |
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There's also a screen at the input of the LP fuel pump. |
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2000 SN GT40 w/99 Graphics/Gel
2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Thanks for the info. Hopefully before the weekend I will have a chance to take a look at it. Me and the family went for a quick ski yesterday afternoon and she is running rougher now than before. I switched to sta-bil where I was using sea foam when I gassed up Sunday and the performance went from bad to worse. I did run the tank near empty before gassing up, so maybe I picked up some trash from the bottom of the tank. I will post my find. Thanks.
One more question. The LP fuel pump..... is it located port side? |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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Unfortunately my boat woes continue. She ran strong for a day, then went back to bogging out of the hole, and not getting over 36mph. I checked the screen at the pump again (clean), cleaned the screen at the 90 entering the fuel tank (not much debris there). I couldn't unthread the dip leg into the tank so I blew air into the tank and it seemed to be clear. Also blew out all fuel lines up to the end of the fuel rails. Just for the hell of it I used throttle body cleaner as well. After putting everything together the boat wouldn't get over 25mph and ran like crap...I re-checked the fuel pressure and it was about 15psi. Any suggestions would be great...I also have a question...I thought the engine only had one fuel pump which was between the fuel tank and the fuel filter, can someone describe where the other one is. I have removed the fuel pump assuming I need to replace it. Once again any help would be greatly appreciated. Scooter, regarding the fuel pump screen...I removed 3 nuts off the top of the fuel pump, removed the cover and it reveals the screen.
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Hey Pete,
I have the tank exposed and I'm looking at two 90 degree fittings at the top of the tank. Which one is the anti-siphon valve? Also... how do I get a look at the screen at the bottom of the fuel dip tube? I did look at the screen on the in port of the LP fuel pump and it looks good. I pulled the in line fuel filter (which is dated by a previous owner 05) and plan to replace it tomorrow. Thanks, Shawn |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Shawn,
Love the boat I have the same one. I saw in your avatar the PO's statement that there was only 100 '95 signatures made. My question is... Is there any info to back that statement up? I checked my serial number but it doesn't reflect that statement. Does anyone know if what he said is true? |
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Hey Paul,
No sir. I have the owners manual and a copy of the certificate of origin, and there is no documentation to back the claim. I am sure Correct Craft Inc. could tell us if we really wanted to know. Or, have you already tried? One thing is certain, it is a sweet looking boat. I hope and pray I can get past this little hic-up I'm having with the "surging" so I can fully enjoy it with my family. |
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Pete,
I checked the screen on the fuel line dip tube and it was clean. The anti siphon valve checked out ok to. The only thing that was visibly wrong was the 1/2 inch foam gasket at the bottom of the cylinder that the fuel line dip tube was in. The gasket was no seated properly, half of it was hanging down into the trap. I siphoned the tank and reseated the gasket. |
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Shawn have you changed the fuel filter yet?
On mine the LP pump is right under the high pressure pump on the port side. |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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Hey Shaun (aka forum jacker) ;) I solved my fuel problem and you may have the same issue. If you unscrew the fuel filter cannister you expose the paper filter and inside that is the high pressure pump. The half inch discharge line (clear hose) going from the pump to the top of the canister which heads to the fuel rails was cracked on mine. Check it closely as even a pinhole leak can cause fuel delivery issues. I replaced the hose and the engine is running great with no surging at all. After you take all this apart remember to turn the ignition halfway a few times to pressure up the fuel system and I also bled a little fuel off of the shraede valve at the end of the fuel rail. Hope this helps.
Scott |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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Just looked at the pic on the previous post, maybe you have a slightly different fuel setup, hopefully my described fix still applies.
Scott |
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Yes I have replaced the fuel filter. It was last replaced 6-15-05 as dated on the filter by the PO. One thng I haven't set my eyes on yet is the fuel/water separator. Is that standard equipment?
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Hey Scott,
almost hate to ask.... I have replaced the in line fuel filter, but the fuel filter canister your talking about is different I'm assuming. My tank has two fuel lines: one going to the LP fuel pump and one that feeds a brass T on the back of the motor starboard side. Off the T there is a hose going to "something" (maybe the canister your talking about). Then there is a solid line that goes to the HP fuel pump. Does that make any sense to ya? |
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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The hose inside the canister that sstewart mentions...
This has come up before. They call this fuel canister the "Fuel Control Cell" or FCC. Google Fuel Control Cell Issues CorrectCraftFan or FCC. You get a smattering of threads related to hesitation etc. Sounds like it could be related. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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The line off the "T" is the return line to the tank. The solid line off the HP feeds the left side fuel rail. The braided line that goes across the back of the motor to the "T" on the starboard side feeds the right side fuel rail. If yours is like mine, as it should be we don't have the FCC that they are talking about. |
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sstewart
Newbie Joined: July-26-2011 Location: Edmonton Status: Offline Points: 28 |
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Yeah, if your engine looks like gun-drivers then you don't have the fcc. Can't remember if you changed out the fuel relay switches (the two grey square boxes lower right in pic above. Read on here they can be a problem...cheap as well $12 each. Thats about all I have to offer dude. Good luck!!
Scott |
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Hey guys,
To no surprise, I am still getting surges while in gear. It's most noticeable while running between 15-20. I openened her up yesterday for about 300 yards at 38 1/2 an she ran like a top. I'm posting some pics of what I thought was the FCC. Ya'll steer me in the right direction. |
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Found this PCM marketing video on the Fuel Control Cell. It should look something like this:
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Brian,
I can't say that I have seen a FCC on mine, which backs up a previous post. Just so I will know, can you identify that component? |
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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I'm not sure what that is to be honest.
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scooter t
Groupie Joined: September-19-2010 Location: Moncks Corner Status: Offline Points: 49 |
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Well for now, I will call it the "flux capacitor".... Thanks for answering my questions. I'm gonna keep plugging along till I solve it.
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I Love to ski, but what I Love more is watching my children learn to Love it too.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Wondering if these things are capable of vacuum leaks too, the way a carburetor base gasket can leak. I imagine it's possible, but never heard of it specifically on the GT-40.
Ok, good luck. |
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kapla
Grand Poobah Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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scooter you neeeed to resize ur pictures 800x 600 or so is the size fits the screen!
Hope you get that squared soon. |
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<a href="">1992 ski nautique
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