94 Ski Nautique Engine hesitation
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=42469
Printed Date: April-28-2024 at 8:35am
Topic: 94 Ski Nautique Engine hesitation
Posted By: CRPilot
Subject: 94 Ski Nautique Engine hesitation
Date Posted: March-07-2018 at 12:59pm
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I'm looking for some help from the local experts. I've been chasing an engine hesitation for more than a season now and I've given up with the local dealers who "can't duplicate" the issue. 94 Ski Nautique PCM 351 Carburated with about 450 hours. The engine starts and idles good but can be a little cold blooded typical to carb'd engines. Once warm, but not completely head soaked, the engine will have a very distinct cut out when pulling a slalom skier up. More throttle = more cutout. After a second to two it catches and pulls up to and maintains cruising speed. Hard acceleration from 25-36 will trigger the cutout as well. A slow, low load acceleration will not cut out. It feels like someone pulls the tether for a second (checked that though ans its tight). After skiing for a bit the cutout gets worse as the engine completely heat soaks. At its worse I can't even pull skiiers up. At that point it feels like its missing on a cylinder or two. The carb's been rebuilt (by me) which had no impact on the issue what-so-ever. I wouldn't rule out carburation thought as it feels like a fueling issue to me. I've read a ton and there seems to be a list of potential issues but I honestly don't have the right tools or in some cased the mechanical expertise to diagnose the problem if I'm staring right at it. -Fuel pump - original -Fuel filter (replaced last year) -Fuel tank check valve?? (not sure what that is) -Accelerator pumps? -Probably many other possibilities... That's where I need someone that is good at trouble shooting. I'm located just west of Milw Wi. Does anyone have a recommendation for a person/mechanic that I can take this too? Or anyone close by and willing to meet me on a local lake and trouble shoot (when the ice goes out)? I don't want to loose another summer to frustration. Looking forward to getting this solved. Jim |
Replies:
Posted By: 63 Skier
Date Posted: March-07-2018 at 1:55pm
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Here's my suggestions: Check the anti-siphon valve at the fuel tank - not at all hard to do Check/replace the distributor cap and rotor, points if it has them. In general check ignition system from start to finish. Check the advance mechanism on the distributor - might not be operating smoothly. Check the fuel pressure delivered to the carb - need to put a gauge in-line. ------------- '63 American Skier - '98 Sport Nautique |
Posted By: 63 Skier
Date Posted: March-07-2018 at 1:57pm
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I'm not from around there, lots of people in your area. But, when you say you don't have the expertise, I'd be very surprised if someone who successfully rebuilt a carb can't do all of the above troubleshooting themselves. Nothing of course wrong with getting some help though! ------------- '63 American Skier - '98 Sport Nautique |
Posted By: KENO
Date Posted: March-07-2018 at 1:58pm
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Sounds to me like it's an accelerator pump issue. You must have replaced the accelerator pump diaphragm and maybe checked the adjustment when you rebuilt the carburetor The easiest thing would be to Google " Holley Accelerator pump adjustment" and make sure it's good and make sure you get a good squirt of gas out the nozzles when you move the throttle. |
Posted By: CRPilot
Date Posted: March-07-2018 at 3:38pm
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Thanks for the vote of confidence on my abilities! I've raced motorcyles and rebuilt my own 2-stroke and 4-stroke motorcycle engines for 20+ years so I have the basic skills to attack some of these issues. What I lack in the specific knowledge of how the 351 fuel and ignition systems work. Not the same as a single cylinder thumper... Forgot to mention this is the Proboss HO so it has the protec ignition. No points to check and to my knowledge no wear parts to replace. Not sure if there are other validation checks for it. Yes, I reset the accelerator pump squirt per the spec'd gap. Don't recall what the spec was but it was checked and there is a solid squirt of fuel when moving the throttle open. My boat is currently in storage but I'm taking notes of what to check when I can get to the boat: -Recheck accelerator pump adjustment -Anti-Siphon valve (hoping there is a "how-to" on line somewhere) -Fuel pressure - What pressure should it be and are there any in-line gauge kits that would be recommended? It'll be 3-4 weeks before I can get to the boat to start looking at this but if anyone is looking for a fun spring project I have one.... |
Posted By: Gary S
Date Posted: March-07-2018 at 3:52pm
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Well there you go then -bad protec. Works good cold then as soon as it gets hot .... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: KENO
Date Posted: March-07-2018 at 4:01pm
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It took 14 minutes for somebody to blame it on the Pro Tec system. Slow day on CCF For CRPilot google 'Correctcraftfan Pro Tec and do some reading.. You've got a few weeks to get thru it all  Whether it's the problem or not, it'll scare you |
Posted By: desertskier
Date Posted: March-07-2018 at 4:02pm
Probably, or it could be IR voltage drop in dash wiring reducing the input voltage at the module. Measure the voltage at the 12.5A breaker on the back of the engine. It should be close to battery voltage. Also, it could be intermittently going into limp mode. Disconnect the oil pressure and engine temp switches on the engine and run it. |
Gary S wrote:Posted By: CRPilot
Date Posted: March-07-2018 at 5:40pm
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I'll read more about the Protec as the thought has certainly crossed my mind. Right or wrong, the reasons I haven't concluded its it protec: 1. The issue exists when stone cold, right off the trailer. But the issue does get worse as everything heats up. 2. The dealer "tested" the protec ignition after an hours worth of run time on the boat (fully up to temp) and didn't detect any issues with the protec (and to be fair found no issue at all. ...)  |
Posted By: desertskier
Date Posted: March-07-2018 at 6:00pm
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Here is an old thread I started after having a problem similar to what you are experiencing. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=1915" rel="nofollow - Wiring problems and some interesting discussions I am not saying that it isn't a fuel problem or a bad coil pack but if it is protec related there are a few things you can check that won't cost you anything and may fix it. Here are a couple of good threads: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=34338" rel="nofollow - DUI Swap http://www.correctcraftfan.com/forum/forum_posts.asp?TID=21901" rel="nofollow - Re-wiring dash |
Posted By: throttle out
Date Posted: March-08-2018 at 9:26am
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Did this issue come on like a switch or was it a gradual progression? When not towing a skier if you ease into the throttle just right will the motor eventually allow full throttle at some point? From what I've read it sure sounds like fueling, when you rebuilt the carb did you use a "Holley" marine rebuild kit? If so that kit would've likely came with two power valves so I will assume you replaced your old one with one of the new ones. If you know four stroke motocross bikes than you well know the awesome Keihin FCR-MX carburetor. That carbs accelerator pump tuning is absolutely critical, so try to treat your boats Holley in the same fashion. Just my 2 pennies! Good luck man! ------------- 1989 Ski Nautique 2001 351 PCM w/ 1-1.23 |
Posted By: Gary S
Date Posted: March-08-2018 at 10:25am
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There is a saying, 90% of carburetor problems are electrical. Please keep us in the loop when you find the cause ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: KENO
Date Posted: March-08-2018 at 11:25am
And about an equal number of ignition problems are carburetor/fuel
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Posted By: desertskier
Date Posted: March-08-2018 at 11:49am
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Another member "TucsonMike" has a '94 and experienced what he thought was a protec failure. His post: "Almost forgot - My symptom is the engine had a rough idle that would sometimes be 900 rpm, then almost die. It was intermittent misfire from the Pro-tec - the port bank of cylinders had fouled plugs, while the starboard bank looked perfect. The PCM guys said that symptom is the coils going bad. So - I have the original ECM with the coils attached and the PCM 'distributor'. Maybe the module is OK... Pay shipping and they are yours... " The DUI swap didn't fix it. He found that one of the gaskets in his carb was the wrong one. Swapped out the gasket and fixed his problem. Boat ran fine after that but later that year he found water in the oil and had to install new risers and manifolds. The good news is that I now carry a spare set of protec parts in my boat. |
Posted By: CRPilot
Date Posted: March-08-2018 at 9:01pm
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Lots of great info guys. Thanks. I have a growing list of stuff to check. Answer a few of the questions: 1. The engine only hesitates for a few seconds or less. Once it pulls through it has never had an issue revving right to top speed (~47 ish). 2. It has never gone into limp mode. 3. Yes, it was a Holley Marine rebuild kit. but it only came with one power valve. I don't recall if it was the same as what I pulled out but I do know that there was a ton of online chat about which one to use. If it was changed by one size, would that trigger an issue? The hesitate was there before the rebuilt and was actually the reason I rebuilt it. I didn't notice any performance change after the rebuild. I never had to deal with the FCR. I ran two strokes (38PWK) until the 4 strokes were EFI. EFI just makes life easy vs jetting for weather and altitude. |
Posted By: desertskier
Date Posted: March-09-2018 at 1:45pm
| If the module is malfunctioning because of low input voltage it may or may not be going into limp mode but the dash light probably would not be a good indicator. When mine was failing it would cutout during acceleration and it was worse when trying to pull a skier. |
Posted By: KRoundy
Date Posted: March-09-2018 at 2:10pm
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Quick question - did you replace the gasket when you installed the rebuilt carb? ------------- Previous: 1993 Electric Blue/Charcoal Ski Nautique Current: 2016 Ski Nautique 200 Open Bow |
Posted By: CRPilot
Date Posted: March-09-2018 at 2:34pm
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I plan to check the dash and ignition wiring as soon as I get to the boat. I have some dielectric grease I can use to combat corrosion if any exists. Which gasket are you asking about? The float bowl, metering block, and primary to secondary tube o-rings were all replaced. Based on all the comments and suggested reading so far far im thinking it’s the anti-siphon or fuel pickup in the tank. While suttle, the problem seemed to we worse with lower fuel tank levels. A full tank didn’t eliminate it but seemed to minimize a bit. I’m kinda looking forward to getting my hands in the boat and checking these things. |
Posted By: Bri892001
Date Posted: March-09-2018 at 5:17pm
I assume Kevin is talking about the carb > manifold gasket. Or potentially, the carb to spacer gasket. A bad (or flimsy) gasket there can cause a vacuum leak, which could give similar symptoms to what you are experiencing. http://www.skidim.com/GASKET-CARBURETOR-SPACER/productinfo/RM0054B/" rel="nofollow - http://www.skidim.com/GASKET-CARBURETOR-SPACER/productinfo/RM0054B/ |
Posted By: CRPilot
Date Posted: March-09-2018 at 7:23pm
| Got it. No I did not pull the carb off the spacer or manifold so those are original. I find it hard to believe that seal would start to fail on a low vacuum application like this...but stranger things have happened. Is there a test to see of the gaskets are bad or is it just remove and replace? "If its not broken, don't fix it.." |
Posted By: SNobsessed
Date Posted: March-09-2018 at 7:31pm
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One test for vacuum leak is to spray carb cleaner on the suspect area, with engine running. If there is a leak the engine will sound different suddenly. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: Dreaming
Date Posted: March-09-2018 at 10:21pm
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CRP - I have a 94 and was experiencing a similar issue that was carb related. You say that you rebuilt the carb, but never pulled it off of the engine? I think a full carb rebuild would be in order, as it sounds much like you have a secondary issue to me. KenO could be on the right track with accelerator pump though, since in either scenario you describe, you would be using it. A carb rebuild would require you to replace gaskets, but more importantly to clean all of the passage ways, replace the needle and seats, adjust the floats etc. Vacuum leaks can develop over time if your gasket (spacer to manifold or carb to spacer, there are usually 2 in a 94HO) are bad, or rattling, or whatever. The carb will come off with the 4 7/16ths nuts on the base, and you can disconnect the throttle arm and choke electrical with the quick disconnects. the only "tricky" part to removing is that you need to get a flare nut wrench on the fuel line, which really isn't that much of a big deal at all. Lots of Online help if you get stuck rebuilding a Holley... Good luck! |
Posted By: Jonny Quest
Date Posted: March-09-2018 at 11:25pm
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+1 on what KENO said. Sure sounds like an accelerator pump issue. As recommended, I would take the carb off and do a complete re-build. Not terribly difficult and lots of material on the internet on the Holley 4160. Summit Racing also has good Holley carb videos. I know that the ProTech system takes a lot of flak, but its justified in many cases. My 1994 had the "double trouble" of ProTec and the throttle body EFI. A ProTech system that is going bad can exhibit a wide variety of symptoms. And like many electronic components, the failure may not always be consistent nor predictable. It's a fairly simple change-out to replace the ProTech to a high performance distributor -- such as a DUI or Davis Unified Ignition HEI system. Lots of info here on that. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: KENO
Date Posted: March-10-2018 at 7:55am
I'm not sure why you think the anti siphon valve or the pickup tube would only affect you coming off idle and not when the boat is running at a steady high speed. Plugging/restriction from those issues will starve the engine for fuel as the speed and load get higher and it sounds like once you get it past the hesitation, then things are OK. Hook a temporary tank to the fuel pump inlet and see how it drives on the water. If it runs the same, you know it's not because of problems with anything before the fuel pump like the pickup tube or the anti siphon valve. Seeing the recent posts, it's hard to tell if you "rebuilt" the carburetor while it was still on the engine based on the gasket comments. You say you don't have much Holley experience,you need to get yourself one of the many Holley books that are out there for around 25 bucks and do some reading. It's money well spent. Here's a link to a thread talking about spacer gaskets and a picture of the spacer. Your's may look the same or a little different, but you can see why they can leak because there isn't a lot of sealing area, they get old and brittle and you have problems. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=42091&title=fuel-system-issues-help-please" rel="nofollow - link Once you figure you've ruled out fuel issues, then it's on to the Pro Tec possibilities |
Posted By: KRoundy
Date Posted: March-10-2018 at 3:35pm
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You rebuilt the carb without removing it from the engine? I think we are all suspicious of this method or rebuilding a carburetor. A full removal and full rebuild would be a good first step. If you do this and it still hesitates, then we can move on to the fuel pump or the Pro-Tec. The write-up on how to install a Pro-Tec is linked in the FAQ. ------------- Previous: 1993 Electric Blue/Charcoal Ski Nautique Current: 2016 Ski Nautique 200 Open Bow |
Posted By: KRoundy
Date Posted: March-10-2018 at 3:45pm
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OK - I will stop being lazy. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=24175&PN=1&title=carb-rebuild-88-2001" rel="nofollow - Carb Rebuild http://www.correctcraftfan.com/forum/forum_posts.asp?TID=34338&title=protec-ignition-swap" rel="nofollow - Repacing ProTec ignition with DUI Note - you need to have the "Photobucket fix" for this to work right. ------------- Previous: 1993 Electric Blue/Charcoal Ski Nautique Current: 2016 Ski Nautique 200 Open Bow |
Posted By: CRPilot
Date Posted: March-14-2018 at 6:50pm
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Been away for a few days but still lots of good info. First off, rebuilding the carb: You can pull both the primary and secondary bowls off the main unit, giving access to the metering plates and associated gaskets. Metering plates were cleaned/blown out, needle and seats replaced, power jet replaced, and jets cleaned/ blown out. The passages into the main body were cleaned with carb cleaner and blown out. Then reassembled with new everything. The carb body does not need to be removed to do that work. I did not remove the nozzel or j-tubs as there is noting to service. They appear to be flowing fuel just fine. For those that have done this rebuild, please tell me what part of the rebuild cannot be completed with the main body attached (other than the obvious manifold gaskets)? I'm not arguing, but I don't understand what part of the rebuild was missed by not removing the body. (again, excluding the manifold gasket). With that said, the manifold gaskets could be an issue and I need to remove that from the equation by replacing it. No argument. What is the consensus on the power jet size? I've read a ton and there doesn't seem to be agreement on one size. Regarding the siphon or pick up tube: My thoughts were upon acceleration the engines immediate demand for fuel from the tank (pre fuel pump) would be at its highest for a second or two (highest vacuum on the fuel line). Once the fuel flow is stable (and not accelerating) any pick up issues might not be as noticeable. Lightly suck on a straw with a hole and you might not notice the hole. Take a strong pull and you will suck air into the straw.....Might be flawed thinking but it made sense in my head. I need to try hooking up an auxiliary tank and see if that helps. I can check these basics when I get to the boat but after that, I may be at the limit of my skill set. I can R&R parts but I still can't compare my abilities to those people that really know these boats and systems. There value is recognizing the minor issues that affect performance in a big way. Thanks again. |
Posted By: Bri892001
Date Posted: March-14-2018 at 7:24pm
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When the engine is accelerating, the accelerator pump is shooting a squirt of fuel that was previously in the carb fuel bowl, so, it's not necessarily a greater pull from the fuel tank at that point. Sustained high speed would give you your greatest flow from the tank perspective. Actually, it sounds like you covered the most important aspects of the rebuild with the carb body still attached. Maybe not the easiest way to do it, but I guess there's nothing inherently wrong with that approach. I'd give your accelerator pump lever adjustment the hairy eyeball one more time. Any play there can give you a bog, that thing needs to be squirting the instant the throttle plates open. |
Posted By: KENO
Date Posted: March-14-2018 at 8:26pm
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Well the most obvious reason is that it's hard to dunk the carburetor in cleaner unless you have a really big tank A few other reasons though are You can't check the tightness of the screws that hold the throttle body to the main body. There are 8 screws and there's a gasket between the main body and throttle body. It would be one of those leftover parts in your kit. I've seen plenty of screws that were not very tight at all allowing the gasket to leak. some. You find those 8 screws when you turn the carburetor over. As mentioned before the gaskets on either side of the spacer should be checked and there's only one way to do that. Did you take the secondary metering plate off so the secondary idle passages and main passages could be cleaned Some gaskets, especially on the secondary metering plate are a royal PIA to get apart and scrape when the carb is on the bench and harder than that when it's still on the engine. You get a lot better look at the idle transfer slots and curb idle discharge ports when the carb is upside down in your hands.and you can blow air backwards through them There are other things too, but you get the idea As far as power valves go, if you put back in the same size you took out, you're not screwing with the Holley calibration and that's generally a good thing. If you don't know what it had you can find the Holley list # on the front of the air horn and post it and somebody will tell you what the original power valve was. By 1994 there's a good chance it was a 2.5 but it's worth verifying. |
Posted By: throttle out
Date Posted: March-15-2018 at 9:11am
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The size of the power valve will not make or break performance but more improve or reduce if that makes sense. I asked you about it to be sure you had in fact replaced it. To narrow this down for you; - given your motor will take full throttle and run well so long as throttle is applied gracefully, I feel as though your fuel delivery to the carburetor is likely sufficient. - The previous statement also tells me your ignition system is likely "good enough" at least This to me is without a doubt an accelerator pump issue that existed previous to the rebuild and has yet to be addressed. I would not go around your boat inspecting anything else until I was certain the accelerator pump circuit on your carb is functioning 100% and is tuned properly. You also indicated it starting hard. This again is an indication of a weak accel pump circuit as it is what shoots fuel down the throat of your motor when you give it a couple pumps before turning the key on the motor when cold. ------------- 1989 Ski Nautique 2001 351 PCM w/ 1-1.23 |
Posted By: CRPilot
Date Posted: March-17-2018 at 8:19pm
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Good points on the carb. I rebuilt it the first time without know exactly what I was lookinf for. From the last post, no, I’ve never had issues starting it. Fires right up every time. I was just pointing out that with the carb it can be a little cold blooded until it warms up good. Like others mentioned, if I dropped it into gear when cold it will stall out sometimes. Once it’s warm it typically doesn’t do that. I thought that was normal but maybe not. |
Posted By: gt40KS
Date Posted: March-17-2018 at 9:52pm
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Carburator issues can be baffling - there's quite literally dozens of possibilities. If it's not a vac leak, could be jet issues. If not that maybe acc. pump or perhaps needle seats. A buddy chased an issue for 2 whole seasons only to find out his electric choke was malfunctioning - after a carb rebuild (twice) and replacing pumps and fuel lines and filters. Anyway, I know absolute zero about the protec so I can't speak to that. But honestly, it sure sounds like a fuel issue to me, and specifically sounds like an over-fueling issue in some respects (loading). Have you checked the condition of the spark plugs when you're having these issues? Didn't think I read anything to that effect. Might not be anything but it only takes a few seconds to pull a plug immediately after an episode. Normal? Or wet..... ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: CRPilot
Date Posted: July-23-2018 at 1:16pm
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Hi Guys, Sorry for the long hiatus. Its been a cold spring in WI and it took a while to get the boat in the water. So here's the latest: I pulled the boat out in spring and dropped it in the water to test. Yup, the hesitation and rough idle were still there. I drained all the fuel and replaced it with fresh gas. At the same time I pulled apart the anti-siphon valve and checked it. No issue there as it was clean and moved freely with very little pressure. Test drove again with new fuel and still hesitated with rough idle but I could slowly nurse it up to full speed. I was lacking time and patience so I decided to take it to a local repair shop that seemed to have a good reputation. The owner also owns a 93 prostar 190 with the same PCM 351 so he was familar with the engine and its characteristics. They checked the basics like fuel pressure, compression, spark, and it all looked good. When checking the carb they found the throttle valve bushings to be worn which was allowing a vacuum leak. While they said it can be repaired, but recommended replacing as the parts and labor to do so were almost as much as a new one.. I was happy to hear they "found" the problem so I authorized the repair. I took the boat out after words and right off the trailer it wouldn't idle. In neutral, it was ok but drop it into gear and it would sputter, chug and quit. I'm pissed at this point. I take it back and explain the issue. They water test it and "can't duplicate the issue". I get the boat back and find they turned the idle up to 1100 rmp and it now pushes a wake at idle. Not good for maneuvering around down skiers.... I then found out they never tuned the carb. Bolted it on and called it done. (stated they come preset). Long story short, I turned the idle down and manually adjusted the idle mixture screws out (counterclockwise) 1/8 of a turn each and it will now idle at 900 in neutral and 700 in gear. Better. The idle is still a little rough but it works. I plan to buy a vacuum gauge and set them properly. So I hop on dry land, grab a quick dinner and decide to put the boat back on the trailer for the night. When heading out to the boat launch I accelerate hard like pulling a skier and the engine falls flat and misfires for 4-5 seconds (just like before the new carb) and then picks up and runs strong til top speed. I repeated the test a few times and it hesitates every time now. Friggin back to square one and the carb does not appear to have been the problem at all! I will say that with the new carb the engine runs really smooth and strong once past the hole shot. It easily pulls 46-47mph with a nice consistent pull. So the new carb isn't a total waste, but it didn't fix the issue I've been chasing. So when it hesitates it feel like its missing cylinders and does not accelerate. Then like someone flips a switch, the power comes on and it pulls strong and smooth. It does not "transition" it just switches from flat to full pull. So I need to ask: What does limp mode feel like? I'm now back to the protec and intermittent issues. The dealer is also out of patience as they "can't duplicate the issue" and I'm tired of paying them $100 an hour to not find anything. I'm thinking of just replacing the protec but I guess I'm hesitating as I really don't know for sure thats the problem. I could easily spend another $500-700 on the ignition and not solve anything. In the ignition and electrical space, I'm out of my league. (little to no working knowledge to test those systems) What the recommended next step? Thanks for listening |
Posted By: Bri892001
Date Posted: July-23-2018 at 1:30pm
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Long shot, since you're having a similar issue with both the old and new carb, but it's a free and very simple fix. Have you dialed in the adjustment for the accelerator pump on the new carb? Specifically the clearance between the accelerator pump diagram arm and the operating lever screw: https://youtu.be/k-Nx5HEzvlY?t=1m20s" rel="nofollow - https://youtu.be/k-Nx5HEzvlY?t=1m20s |
Posted By: CRPilot
Date Posted: July-23-2018 at 3:14pm
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I skipped a little bit of the story in that I had the boat in the water 3 times with the new carb and the acceleration was perfect. Just chasing the lack of idle/rough idle issue. Because of that I think the accelerator pump setting is ok. It came out of the hole just fine for three trips to the lake. Then when I adjust the idle mixture screw 1/8 a turn and I get a hesitation. |
Posted By: Bri892001
Date Posted: July-24-2018 at 2:03pm
| I've seen some say it's better to get your idle dialed in with the boat in gear (under load). |
Posted By: CRPilot
Date Posted: July-25-2018 at 11:09am
| I plan to do it in gear. Seems to idle well in neutral then chug and die when in gear. |
Posted By: Bri892001
Date Posted: July-25-2018 at 11:19am
| Also, make sure you double check for a vacuum leak, as mentioned by Snobsessed on page 1. Not sure if this was mentioned, but it's preferable to use the marine specific base gaskets to help to avoid vacuum leaks https://www.skidim.com/GASKET-CARBURETOR-SPACER/productinfo/RM0054B/" rel="nofollow - https://www.skidim.com/GASKET-CARBURETOR-SPACER/productinfo/RM0054B/ |
Posted By: MrMcD
Date Posted: July-25-2018 at 8:06pm
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On the Holley carbed boats I have owned I found the ski boat idle worked better when I left it slightly rich. The adjustment screws on either side of the carb could be adjusted for a good idle on the trailer but in the water I would open them up maybe 1/2 to 3/4 turn each and the in water idle would be much stronger and not die or chug. It also started better without touching the throttle. Slightly rich but seemed to be the answer in my Holley carbs. ------------- |
Posted By: GottaSki
Date Posted: July-26-2018 at 11:14am
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Exactly...and generally good advice for all carbs Adjusting idle mix No-load by max max idle rpm method will produce an off-idle lean stumble and warm starts requiring throttle input. setting idle mix in forward gear set the most , stable, resilient and torquey idle, which produces minimal delta in rpm when placed in and out of gear. decades ago, if your car had an automatic transmission, idle and idle mix was set in gear, precisely for this reason ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: CRPilot
Date Posted: July-30-2018 at 1:40pm
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Thanks all. I set the idle on the trailer and then dropped in in the water to reset it in gear. Its much better but not perfect. I think its just my tuning may not be dialed in yet. (First time ever setting the idle with a vacuum gauge). It no longer dies but it does drop a little rpm. I'm finding that the best vacuum while in gear pushing through water comes at about 3/4 turns out from full in. That sounds off from just about every "how to" I've read that suggests the sweet spot should be 1.5-2.5 out. This is starting out at the lowest idle possible without stalling to avoid pulling fuel through the transfer slots. Its nets a healthy vacuum of 16-17 inches. Even with the idle set I'm still getting an intermittent engine miss on hard acceleration. Its only after I follow this routine: -Start up cold off the trailer (no problems) -Warm it up good/use it for skiing 30-40 minutes (no issues) -Shut is off and go swimming/whatever for 25-30 minutes so the whole engine bay heat soaks. -Start it up and it will no longer accelerate smoothly. Off idle the engine sounds like its missing cylinders for 3-4 seconds then clears up and appears to run ok. I can run it top speed and repeat and it still hesitates (just to make sure its not a fuel load up issue). I'm thinking about just ordering a new ignition and pull the protec. While I can't seem to prove that's it for sure, I also can't prove its not. Another summer 1/2 gone and its still not right. Now DUI or the SKIDIM package: I need to read pros and cons about each. |
Posted By: Jonny Quest
Date Posted: July-31-2018 at 2:24am
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No disrespect to Vince and the folks at Skidim, but the DUI is a much better system in my opinion. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: KENO
Date Posted: July-31-2018 at 9:07am
You must have some reasons you could list for him JQ By the way you might notice that SkiDim sells the DUI distributor now for 351 RH rotation engines. Strangely enough they don't have the normal rotation version listed on their website |
Posted By: CRPilot
Date Posted: August-02-2018 at 11:39am
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ok. Spent some more time yesterday just checking the basics so I can throw the boat in the water and test/disconnect the oil pressure, water temp, and knock sensors to see if that eliminates the issue. I also pulled the plugs to check condition and gap. I found something that looks strange to me but not sure if its normal. The two plugs on each side towards the front (of the boat) are perfectly clean, almost new looking. The rear two plugs are brownish. I would have expected them all to be very similar. Is this normal or a sign of a tuning issue? 
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Posted By: SNobsessed
Date Posted: August-02-2018 at 2:45pm
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The dirty plug is 1% towards being a problem, IMO. Keep looking. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: Jonny Quest
Date Posted: August-02-2018 at 10:27pm
When I started my ProTec swap-out project a couple of years ago, I started out by ordering the Skidim kit. After getting the kit, I was unimpressed, particularly when I compared the Mallory distributor to the DUI unit. I returned the kit back to skidim and went with DUI. One 12V feed wire and 1 tach output wire. Done. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |