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GT40 conversion to carb |
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MrMcD 
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3749 |
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 Topic: GT40 conversion to carbPosted: August-01-2023 at 11:43am |
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The pump is cooled by the fuel flow. I suspect the pump is failing and the wires are what are getting hot from too much load. Fuel in these pumps flows right over all the moving parts. They normally do not get hot unless your fuel flow is restricted or you are out of gas. If these pumps are run dry, no fuel flowing they self destruct in a matter of seconds.
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BobinIL
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Joined: July-29-2018 Location: Illinois Status: Offline Points: 36 |
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Posted: August-01-2023 at 10:53am |
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I took it to Liquid Edge in Farmer City. Doug is an old friend of mine and has made some progress. He has had it for about a month and determined that the HP fuel pump is getting hot and cutting out. It will continue to run with the engine cover up to aid in cooling. We are currently looking for restrictions in fuel flow. Possibly the return line.
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Gary S
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Posted: June-26-2023 at 12:09pm |
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What dealer did you take it to Bob?
most don't seem to want to work on something over 10 years old. I suspect it's more like eats alot of time and not many have the experience or access to parts.
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BobinIL
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Posted: June-26-2023 at 6:57am |
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I will be following this tread with great anticipation as well, my 97 sport GT40 has ben unusable for 3 years now due to the engine cutting out one warmed up. I have literally changed everything but the ECM. My local dealer has it now trying to figure out what is going on. I am so fed up with this thing that I would gladly convert it to carb if i would have a reliable boat again.
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63 Skier
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Joined: October-06-2006 Location: Concord, NH Status: Offline Points: 4269 |
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Posted: June-19-2023 at 12:40pm |
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I will also watch for your updates with great interest. Best of luck with the work!
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'63 American Skier - '98 Sport Nautique
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macey
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Joined: July-22-2018 Location: Ireland Status: Offline Points: 19 |
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Posted: June-19-2023 at 11:07am |
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Have ordered all parts required to convert to carburetor. I'm sure there will be others who will in the future consider this change and possibly some currently who are considering it. I will leave an update of my conversion as and when it completes and report on how it turns out. Many thanks again to Jonny Quest and Keno who have been a great help. At current prices with top quality compnents the parts cost of conversion is pretty much exactly $2000.
Once removed I intend to have both the ECU and the loom tested, part of me would still like to diagnose the initial problem but at 22 years of age I would assume I will not refit the injection system. Will keep you posted.
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Jonny Quest
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Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2978 |
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Posted: June-15-2023 at 10:08am |
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JQ is watching this thread very closely.
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11112 |
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Posted: June-15-2023 at 7:58am |
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I think on my Summit shopping list I'd have
An intake manifold, Edelbrock Performer, Performer RPM, Weiand Stealth Carburetor mounting studs SUM G-1423 should be good An adapter plate SUM G-1420 if you're using an Edelbrock performer. It provides a wider seating surface for the carburetor. Intake manifold gaskets FelPro 1262 S3 work good A carburetor of your choice An oil pressure safety switch for the fuel pump. Holley 12-810 is easy to wire and works good. Your new LP fuel pump for the gt40 should work just fine supplying a carburetor since PCM used it for that purpose on some carbureted engines. Some marine fuel line from pump to carnuretor A marine distributor of your choice. If a DUI is your choice, it looks like you'll need a second choice because Summit's shipping dates on the DUI for your Ford all seem to be at least a couple of months away. You may need to talk to a human voice on the phone about this. They do have A Pertronix D231800 and you'd need a coil like a Pertronix Flame Thrower to go with it. You could shop at SkiDim or Nautique parts and pay way, way over list price for a DUI distributor if they have it in stock  A flame arrestor, not knowing how much clearance you'll have between the engine box and your carburetor depending on manifold choice, the lower the profile, the better. What works on a Holley doesn't necessarily work on a Quick Fuel due to the external float adjustment screws on the Quick Fuel sticking up a bit. A little dimpling of the bottom of the arrestor sometimes helps. It's getting a little pricey, but does what you want to do............ like save your summer and let you go skiing And very importantly..............you will be Jonny's hero for actually doing this but only if you use a Quick Fuel and a DUI with a RED cap
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bwinn
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Joined: July-13-2009 Location: ct Status: Offline Points: 396 |
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Posted: June-14-2023 at 8:28pm |
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https://correctcraftfan.com/forum/forum_posts.asp?TID=25584&OB=DESC
Read if you’re not familiar with yet. You can fix this. Hang in there. There’s a YouTube video of a dude checking all the sensors on one of these makes checking alot of them simple. I feel like you will be better off in the long run to fix rather than swap. Good luck Burton |
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macey
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Joined: July-22-2018 Location: Ireland Status: Offline Points: 19 |
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Posted: June-14-2023 at 5:21pm |
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So the alternator did not cure the issue. New one fitted and no change to idle.
Distributor also fitted today with no solution. I did buy an Inova 3145 fault reader but it did not communicate with the diagnostic port. Perhaps it was not the correct choice. I am going to proceed with a complete strip out and carburetor installation now. I may return to the fuel injected set up if I feel dissatisfied with the result but I do crave the simplicity and the greater availability of knowledge. Part of me would be quite determined to actually resolve the issue, it does feel like it should be quite simple but summer is short so carb it is. Jonny and Keno, as already mentioned I am over in Ireland so sometimes parts can be little slow for me. Summit were excellent with international shipping on the injectors so I will probably use them for the carb stuff. It would be great to organise everything I need in one order (gaskets, flame arrestor, etc) so would be much appreciated if you would take a little time to ponder a complete carb fitment. I will obviously keep you guys posted on the results and my "feelings" on the performance and general difference after the change. Yet again many thanks.
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63 Skier
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Posted: June-11-2023 at 11:18am |
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The electronics want to see steady voltage. Without a charging alternator, that is just over 12 volts when the battery is charged, but dropping with discharge and maybe general battery health. With a functioning alternator you are seeing 14 plus volts steady all the time. I'd absolutely make sure you have a working alternator and a battery in decent condition as your next steps.
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'63 American Skier - '98 Sport Nautique
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macey
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Posted: June-11-2023 at 6:42am |
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63 Skier, yes replaced the rotor. I was careful to replace plug leads one at a time so I would be fairly sure they are correct. (will actually do a check just in case) but it does run for a very short time correctly so I think they are ok.
Jonny, I did a leak test on fuel system and it started at 40 psi and remained above 38 after 5 minutes. I took the vacuum pipe off the FPR and there was good suction from it. Fuel pressure increased by about 5 psi when off, no sign of any fuel leaking past. I will probably change the regulator if I can pick one up locally but doesn't feel like the issue. Fuel pressure does fluctuate when the idle starts to wander. I think this is more a result than a cause but obviously not sure. One final point for this post. When I did my list of what I had done up to now I did replace the alternator 3 years ago. Actually writing this down reminded me that I had not actually checked for charge. As it turns out the alternator is not charging! Can a faulty alternator cause poor engine running? I do have a new distributor but I have never fitted one before. I believe the distributor gives the crankshaft position information to the ECU. Is this correct? If the distributor is an easy fit does anyone have a link to a good step by step guide? Yet again, many thanks.
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Jonny Quest
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Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2978 |
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Posted: June-10-2023 at 11:26pm |
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Fuel pressure regulator?
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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63 Skier
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Posted: June-10-2023 at 5:23pm |
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2 items come to mind, both obvious but figured I'd mention them. You replaced the distributor cap, how about the rotor? And did you verify the firing order when you replaced the plug wires?
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'63 American Skier - '98 Sport Nautique
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macey
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Posted: June-10-2023 at 11:13am |
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OK, the problem persists.
Idle is much worse than when I last ran the boat 2 years ago and obvious even when cold. 2 years ago idle issue did not cause a problem until engine had warmed up.
Injectors fitted but this has not solved my issue. I will give a summary of what I have done up to now and I would very much appreciate any input if there has been something obvious I may have missed. I have removed and clenaed out fuel tank filled with fresh fuel. Replaced fuel pick up pipe. Replaced fuel lines to and from tank. Checked tank breather. Replaced check valve (it was quite noisy when drawing fuel) Replaced both fuel pumps. New FCC filter, seal and pipe. Replaced both relays. Replaced injectors. I have removed and refitted all connections to check for disturbed cables and lubricated with contact oil. Cleaned flame arrestor. New engine battery, alternator was replaced a couple of years ago. Replaced distributor cap and leads. Replaced Ecoil, Map sensor, TPS sensor, IAC valve, air intake temperature sensor, TFI module. Replaced water and oil sensors. New distributor cap and plug leads. I have not replaced the knock sensor or the distributor itself and not the ECU. Fuel pressure is just under 40psi when I first start up but drops when engine starts loping. Some form of vacuum/air leak is possible but some direction on how to check this would be great. I did check and clean the wire filter at the IAC valve. As I have said already assume nothing, it is entirely possible I have missed something simple. For the guys who have been helping me up to now, if there is any way to link this post to anyone else you are aware of who has come through this and is also knowledgable that would be super helpful. I am probably at the end of my ability with this and I must now consider removing everything (at least for the remainder of this season) and try a carb. I get the feeling even if I do that I may refit everything during winter just to finally get an answer. Many thanks again everyone. |
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KENO
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Posted: June-09-2023 at 6:50am |
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I call it a filter, never replaced it though
I think car guys may have a check valve associated with the vacuum lines in that area since there's a lot more vacuum plumbing on a car. PCM has a part number for it and they call it a MAP fuel vapor filter. Part number is R077008 I think what you call the plenum and the upper intake are the same thing.
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macey
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Posted: June-09-2023 at 2:03am |
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Keno, that is a perfect description, exactly the part I am talking about. Does it require attention?
Gary, yes got adapters thanks to the links provided. Jonny, by intake manifold, do you mean the big silver thing? I had referred to this as the plenum chamber but I’m no expert? Thanks again gentlemen. |
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Jonny Quest
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Posted: June-08-2023 at 11:53pm |
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Before attempting to remove and replace the fuel rail, pressure regulator and injectors, REMOVE THE INTAKE MANIFOLD (upper half). It’s waaaay easier. The voice of experience…
JQ
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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Gary S
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Posted: June-08-2023 at 11:07pm |
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Hope you got the harness ev1 to ev6 adapters
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KENO
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Posted: June-08-2023 at 8:24pm |
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Jonny Quest would probably tell you that it's a lot easier if you remove the upper half of the manifold.
If that little white thing has an arrow on it and the line runs to the MAP sensor, some people call it a filter and others say it's a check valve that doesn't seat real tight and it acts to dampen or smooth out the signal to the MAP sensor I don't think they get much of any maintenance
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macey
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Posted: June-08-2023 at 4:21pm |
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Hi guys. New injectors arrived today very promptly from Summit Racing. Hopefully get a chance to fit tomorrow or Saturday morning. First time fitting injectors but doesn't look too scary. Any tips or advice?
One item that I have not found a reference to is a little white unit connected to breather pipe under plenum chamber. What is this and does it require maintenance or replacement? Thanks again, Neil.
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KENO
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Posted: June-05-2023 at 7:54pm |
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Since Moates closed the doors and went out of biz in Nov 22, finding a chip to work in place of their F3V2 chip which is used to copy the ECM tune onto and then put it into an old 4 cylinder Mustang ECM to make your spare or maybe desperately needed gt40 ECM is rather tough.
I haven't seen a reasonable solution come up yet
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Jonny Quest
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Posted: June-05-2023 at 7:29pm |
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I don't think that Macey feels that carb is better than EFI, but simply an option for consideration if the EFI and associated systems become too troublesome. My feeling as well. I'll keep my GT40 in the factory configuration until such time as EFI / ECM problems and parts availability push me toward old school carb / distributor.
JQ
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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63 Skier
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Posted: June-05-2023 at 12:11pm |
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Sounds like a solid plan. I don't think many people will say that a carb setup is better than a GT-40 efi. Better than the earlier years Protec, yes, but the GT-40 is an amazingly good setup for easy starts, idle, skiing, etc. The general problems have been diagnosed and can be overcome. The lack of ECM replacements have led people to do a carb conversion and I've wondered if I would do that if/when mine fails, but seems like these days you can get a replacement ECM, though they are expensive. Like you, I'm doubting your problem is the ECM. I hope the injectors fix it for you.
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'63 American Skier - '98 Sport Nautique
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macey
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Posted: June-05-2023 at 10:50am |
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Hello 63 Skier. I stopped using the Nautique in September 2021. At that point in time it ran perfectly on throttle, pulled no problem, but would not idle.
I searched the forums and did many of the simple things like IAC, plugs, leads, distributor cap, fuel tank breathers etc. but none of the larger items like injectors. The original fault felt quite minor, most probably to my mind a sensor. I decided during the winter to do a fairly substantial refurbishment to the boat and hopefully at the same time replace the offending component. Engine removed, new carpet, lots of powder coating, all looks great but when I started it for the first time last week it sounded poorly, far worse than when I last ran it in 2021. Not off a cylinder but just very lumpy. A little rev will clean it up slightly but it does remind me of a fuel rather than ignition fault. Ordered injectors this morning, I really don't believe it is the ECU (perhaps that is more hope than belief lol). I also have a new distributor to fit. I am keeping the carb as my back up plan for next week but fingers crossed the injectors cure it. Jonny Quest and Keno have probably done enough to convince me carb is a good option but it has always been my understanding that fuel injection is more effecient therefore better performing than a carb. Over in Europe we have had very few carb engines for many years now, we just do not have cars with 5.8L engines. Very much enjoying the input from you guys and I will keep you posted once injectors arrive. Thanks again, Neil. |
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63 Skier
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Posted: June-05-2023 at 10:30am |
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Neil, in your first post you mentioned it has idle issues, then later said it ran truly awfully. Is this just at idle or also at mid range and high speeds? Before you tear the efi out, I'm wondering how much you've looked at the ignition side of things. You said plugs were replaced, how about plug wires? Distributor cap and rotor? These relatively cheap components can really make an engine run badly. You asked about getting back to efi HP once you have a carb on it. I'm curious what the answer to this is, I don't remember any discussion about it. I'm wondering if there is any HP loss with a well done carb setup over the efi, I don't really expect there would be. More fuel consumption yes, but loss of power no. Curious for anyone's thoughts on this.
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'63 American Skier - '98 Sport Nautique
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Jonny Quest
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Posted: June-04-2023 at 11:28pm |
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The injectors and adapters KENO referenced are currently installed in my GT40. I’ve been pleased with the performance thus far.
JQ
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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KENO
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Posted: June-04-2023 at 7:45pm |
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Quite a few people have used the Ford Performance injectors like in the link below available from numerous places And here's a link to a thread talking about them and the adapters that come with them. You need the adapters because the later injectors have a different style plug on the injector. |
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macey
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Posted: June-04-2023 at 4:55pm |
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KENO and Jonny Quest, thank you very much for your help. As a result of you help I am happy that the carb conversion is entirely possible for me. All parts appear to be available readily, even for someone over in Ireland. My initial post was prompted when I started the boat after a two year lay up during which I replaced all sensors, plugs, pumps, hoses and so on. It ran truly awfully. My remaining suspects for my initial problem were the injectors and/or the ECU. Idle and vibration was so bad I am quite hopeful the issue lies with the injectors.
My plan is to try a set of injectors this week and if that cures it great, if not the carb it is. I always had a carb and some form of performance tune in my head as a perfect project for the 196 but the tuning bit is probably not an option for this season. I am happy I can do the carb conversion at short notice if the injectors don't work out. KENO, I believe you recommended a set of injectors from Summit Racing in a previous post, is this still my best option? Many thanks again for all your help guys.
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KENO
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Posted: June-03-2023 at 12:41pm |
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As far as your keypad question, I don't think there will be any issues there. The keypads are associated with the PME box under the dash and as long as you maintain power to the box you shouldn't have any issues.
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