Running rough - full explanation inside
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=36006
Printed Date: October-07-2024 at 10:49pm
Topic: Running rough - full explanation inside
Posted By: calebcl
Subject: Running rough - full explanation inside
Date Posted: May-10-2015 at 8:53pm
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Hi all, Myself along with Andy Stinespring (another member on the forum) own a 1990 ski Nautique with the PCM 351 engine. I'll list everything about it, then explain what is going on. Hopefully one of you has some semblance of a clue what's going on, as I am at a loss at this point. Long story short, we have owned the boat for a little over two years now. Year one was bliss. The engine ran perfectly with no issues. One day it died on us, forcing us to swim it in. This is the first of many similar experiences. At this point, here's what has been done (all in the last two weeks or so) Carb taken apart, soaked and rebuilt - new front float bowl. New fuel braided (rubber) fuel line from the carb to the new Holley manual fuel pump New clear fuel line from the filter to the pump New distributor cap and rotor All new spark plugs - gapped at the recommended .35. Straight pipe exhaust added back in May of 2014. After two weeks of getting all of those items mentioned above replaced, I have begun taking the boat out for tuning. I finally got it tuned to my satisfaction (essentially each mixture screw is out 1.5 turns, and the idle screw is almost all the way out). My wife and I took the boat out today with exciting results....for about an hour. It idled wonderful, pulled hard and was overall an ideal experience. Then, all of the sudden it began idling very rough, seeming not to run on all cylinders. Low on power and shuddering. I checked the wire from the coil to the distributor and it was seated properly, I the boat seems to be getting spark, it's definitely getting fuel (can see it flowing through the clear line). The accelerator pump is functional, and the water strainer was clean (not sure if that matters) the boat idled very poorly for a bit, and I tried to get back to the dock. Eventually it died. We sat there for a bit, it fired up again (but still very rough) I put it in reverse, and it smoothed out inexplicably. Put it in forward and was able to idle smoothly through a long canal - toward the end of the canal it began to run rough again. I tried reverse again with no effect. Got about half way to the dock and it died again. After several attempts to make it turn on, we had to be towed in. In the middle of being towed, it started up again!! We got it to the dock and it idled very rough for about 7 minutes at the dock then died. I sincerely hope someone has some ideas!! I'm lost!!! Thanks so much! Caleb. ------------- Caleb |
Replies:
Posted By: backfoot100
Date Posted: May-10-2015 at 9:22pm
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I'm curious why the carb rebuild and new fuel pump? Next one is why you do all that and not touch the points or timing? ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: calebcl
Date Posted: May-10-2015 at 10:31pm
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Carb rebuild because I had it looked at by a Nautique mechanic and he said it needed doing. New fuel pump because it was original and didn't seem to want to prime. New one is a 7cfm Holley - not the higher performance model, as that would be too much pressure. The answer to your second question is that I'm a novice and that's new to me. I dont know if the timing is maladjusted, and was told that a cap and rotor change would not require timing adjustment. Update: walked out to get something out of the boat and thought "what the heck" and wouldn't you know it fired up?? Even idles fine. (This is on the hose, not in the water) So much confusion! So to sum up, once it takes a break, it will run fine for a while then get rough and die. ------------- Caleb |
Posted By: KRoundy
Date Posted: May-11-2015 at 2:03am
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Coil heats up and then causes problems? Under a low load or not running it cools off and then runs good for a while? I'm no expert either. Curious to see what others say. ------------- Previous: 1993 Electric Blue/Charcoal Ski Nautique Current: 2016 Ski Nautique 200 Open Bow |
Posted By: calebcl
Date Posted: May-11-2015 at 8:32am
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In fact, I did notice the coil getting hot...I replaced the coil a year ago, but with the exact same one - could be inappropriate for marine?? When we bought it, the previous owner had had the motor and transmission rebuilt two years prior and it only has 275 hours on it...but again, the coil did feel very hot... ------------- Caleb |
Posted By: Bri892001
Date Posted: May-11-2015 at 9:05am
| You could be getting warm on the hot coil. Sounds like Kevin put you on the right track. Post some pics of your ignition setup. |
Posted By: calebcl
Date Posted: May-11-2015 at 9:55am
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Pictures of ignition set up attached. Looking forward to hearing thoughts. Please don't be too hard on me if the setup is terrible! haha     ------------- Caleb |
Posted By: mamigacz
Date Posted: May-11-2015 at 10:34am
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There really isn’t anything that makes a coil marine. Some people prefer to use epoxy filled (as opposed to oil filled) because they hold up longer from the constant bouncing around of the boating environment. However, the norm is to use oil filled because they stay cooler. The part you have to be careful with is some coils require 12 volts (no ballast resistor). Some coils require 9V (using the ballast resistor). You first need to determine is if the ballast resistor is being used or not. See the link below. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=33866&title=90-sn-to-electronic-ignition" rel="nofollow - Ballast resistor information |
Posted By: Bri892001
Date Posted: May-11-2015 at 11:26am
| Also, some oil filled don't like to be lain on their side. |
Posted By: calebcl
Date Posted: May-11-2015 at 11:33am
 As shown, I do have a ballast resistor. My 351W is a left rotation, fyi... ------------- Caleb |
Posted By: JoeinNY
Date Posted: May-11-2015 at 11:35am
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its a correctcraft so checking the quality of the wiring and the actual voltage reaching the ignition system is always a good idea. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: calebcl
Date Posted: May-11-2015 at 11:45am
 Here is a stock photo of the ignition coil I'm using. Accel M19149 (8140). It IS apparently a 12 volt coil, but it seems to be routed through the ballast resistor...Keep in mind, I replaced that coil in May of last year, but purchased the EXACT same coil, and didn't change how it was wired - prior to replacing it (prior to it dying) it had run very well for about 8-9 months (aka since we bought the boat). Could it be wired wrong? ------------- Caleb |
Posted By: mamigacz
Date Posted: May-11-2015 at 5:10pm
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It looks like you have a YLM554CV breakerless distributor. It sure appears like your doing the right thing by using the ballast resistor with that coil. I wonder if there is water in the gas? |
Posted By: calebcl
Date Posted: May-11-2015 at 9:05pm
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Highly unlikely, it's brand new gas...corrosion in the electrical components of the electronic distributor?? Took a few pictures of it earlier. Will post momentarily ------------- Caleb |
Posted By: calebcl
Date Posted: May-11-2015 at 9:22pm
 Photo of inside the distributor ------------- Caleb |
Posted By: oldcuda
Date Posted: May-11-2015 at 9:39pm
| Have seen the module in distributor act just like that when they start getting hot, Remove it and look for cracks.Maybe just replace it. |
Posted By: calebcl
Date Posted: May-11-2015 at 10:31pm
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That kind of confirms my suspicions. I was speaking with a mechanic earlier today that said the same thing. I ordered that part this afternoon! Should come in tomorrow or Wednesday and we'll see how it works! I'll take the module off tomorrow and evaluate it. Will replacing it alter the timing? If so, best procedure to calibrate that? ------------- Caleb |
Posted By: gun-driver
Date Posted: May-11-2015 at 11:06pm
Before changing parts I would go with Joes advise |
JoeinNY wrote:Posted By: Bri892001
Date Posted: May-12-2015 at 12:31pm
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Hopefully you guys are on the right track. I'll just add one more simple check to your list. Make sure your coke is opening fully and staying open once the boat is warmed up. |
Posted By: mamigacz
Date Posted: May-12-2015 at 12:50pm
Nope. You won't affect the timing by replacing the module. |