351 running rough
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=23401
Printed Date: May-04-2024 at 3:01am
Topic: 351 running rough
Posted By: Jllogan
Subject: 351 running rough
Date Posted: September-06-2011 at 3:06pm
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http://correctcraftfan.com/forum/forum_posts.asp?TID=23274&title=distributor - Previous Thread
Ok so my engine is still running rough no improvement and I have narrowed it down a little. I think the timing/distributor is checking out, I have either replaced or checked everything I could and it says its in time. The only thing I havent checked is the coil as I am not sure what to look for. I think the whole issue may have been and still is water in the carb. I ran about 4 gallons of clean gas with seafoam through it and no improvement. I took these pictures last night right after running. It looks like water is still condensated in the secondary throttle plates. What do you guys think I should do? Does that look like water to anyone else? Also the jet by my thumb in the one picture is putting out a solid stream while at an idle and the jet on the other side is just dripping. Could water cause that issue? or has the water created other problems.   ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Replies:
Posted By: skyway2k
Date Posted: September-06-2011 at 3:23pm
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It does look like water to me, but were you running the boat drivin around on the lake or just idling? Your secondaries would have never opened just running in place and not under a load. Probably condensed some water on the plates after the engine warmed up.
Have you looked at your water separator? Is it full of water? Maybe you should try completely draining out whatever gas you have in the tank and put in fresh if there's a lot of water. Also, your secondary barrels; are those cracks in the barrels? Or just casting marks that have picked up some dirt? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5240&sort=&pagenum=1 - '91 Ski Nautique |
Posted By: Jllogan
Date Posted: September-06-2011 at 4:05pm
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its just dirt. I have not been to the lake for over a month as the boat hasnt been running right. That was after idling in the garage for 10 minutes.
What do you think about the different amounts of fuel coming out of the sprayers? This carb was rebuilt 50 hours ago and ran fine. I have been running out of a gas can straight into the fuel pump. I am trying to get it running right before I go through the trouble of draining the fuel tank etc. What about the coil, if it was going bad would it run rough (miss) and backfire? I thought the ballast resistor was supposed to reduce voltage but I am getting 12 volts on either side of it. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Jllogan
Date Posted: September-06-2011 at 4:29pm
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Also I noticed I think my tach is innacurate for some reason. It wont go any lower than 1K even if i drop the idle way down. Sounds like under 500. Does that point to a coil issue? I may have put it on the wrong post, which side should the gray wire be on? ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Bri892001
Date Posted: September-06-2011 at 6:02pm
I think it's possible to see condensation around your carb barrels because the vacuum around that area causes the air to cool and any moisture can get dropped out. As far as one yet spurting a lot and the other just dripping. I don't think they're really supposed to be doing anything at all when at idle. The idle circuit, which discharges underneath the butterflies is supposed to take care of everything. Dripping might be possible, but I'd say spurting is definitely wrong. Of course, your accelerator pump should spurt, but only as you are revving the throttle, not when idling. Sounds like you could be due for a rebuild or replace on your carb. Not sure if water would cause the issue or not though. Not sure on the coil thing. |
Jllogan wrote:Posted By: Jllogan
Date Posted: September-06-2011 at 6:34pm
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do you think the floats should be rebuilt too? I didnt rebuild those the first time.
I thought of another thing, When it first started running rough it was idleing at about 250 rpm, so I tightened the idle screw to compensate, that could be causing the pump to dump a bunch a fuel in. doesnt explain why they arent the same, but it could explain why its pumping some. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Jllogan
Date Posted: September-06-2011 at 6:36pm
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maybe, Ill run it and take some videos/pics tonight and post for a diagnosis. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Bri892001
Date Posted: September-06-2011 at 6:49pm
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I know the floats can be replaced. They sell a new plastic kind that I've seen on Skidim. It says the old ones can become poruous, fill with fuel and not "float" as well.
Floats and power-valves (and maybe other things) can cause fuel leakage like that. Not sure how the idle adjustment would affect it. |
Posted By: Jllogan
Date Posted: September-06-2011 at 6:59pm
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not the idle adjustment screws on the bowl but the throttle idle screw.
I have the new plastic floats which are supposed to be bulletproof so I never changed them. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: skyway2k
Date Posted: September-06-2011 at 7:02pm
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When you have the float bowls off the carb and held in your hand upside-down, are the floats sitting parallel with the bowl top? This is a quick check to see if you have a good starting point for the float level. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5240&sort=&pagenum=1 - '91 Ski Nautique |
Posted By: Bri892001
Date Posted: September-06-2011 at 7:03pm
| There's a piece inside the bowl that's replaceable, right? The needle and seat I think. |
Posted By: Jllogan
Date Posted: September-06-2011 at 7:11pm
yes the adjustment is like you say. or at least it was at the beginning of the year. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Jllogan
Date Posted: September-06-2011 at 7:12pm
You are right, I didnt replace that on the rebuild either. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: kapla
Date Posted: September-06-2011 at 7:16pm
where´s 79nautique? he is the one for this tail chasing threads!  ------------- <a href="">1992 ski nautique |
Posted By: Bri892001
Date Posted: September-06-2011 at 7:19pm
Yeah, he is missed 
He had a lot of good knowledge. He may have insulted the heck out of you while he was explaining something to you, but at least he would explain it. |
Posted By: kapla
Date Posted: September-06-2011 at 7:20pm
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FU##ing FUNNY ------------- <a href="">1992 ski nautique |
Posted By: kapla
Date Posted: September-06-2011 at 7:22pm
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are the air/fuel screws working right? if you close them all the way the engine stumbles?
------------- <a href="">1992 ski nautique |
Posted By: Bri892001
Date Posted: September-06-2011 at 7:28pm
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LOL.
Kap, I think the test you mention above is a test of the powervalve. If the engine keeps running the same with them closed all the way, it means the powervalve is ruptured. |
Posted By: Jllogan
Date Posted: September-06-2011 at 7:30pm
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well it stumbles to start with. Ill screw them in all the way and see if there is a change. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: kapla
Date Posted: September-06-2011 at 7:34pm
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yes, and the idle circuit as well (think). But if you are dripping most likely your floats are not closing right...you should see no dripping @ idle...only a nice even squirt when you hit the throtle....
------------- <a href="">1992 ski nautique |
Posted By: Jllogan
Date Posted: September-06-2011 at 7:43pm
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I am thinking that by me adjusting the throttle linkage/idle is why its squirting in gas. By screwing it down its the equivalent of throttling up. There is no dripping after I shut it off thats what makes me think the floats are ok.
Who knows Ill test a few more things tonight and see what I come up with. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: GottaSki
Date Posted: September-06-2011 at 8:33pm
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Bet anything your idle circuit is clogged.
You shouldn't see anything from the main boosters at idle. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Jllogan
Date Posted: September-07-2011 at 12:18am
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Ok so the tail chasing continues. I think there were and are a few things wrong with the engine. Tonight I tested the plug/plug wires with one of those inline spark testers and the spark on pistons 2,3,6 and 7 was very weak. The light was barely on and it was very bright on 1,4,5 and 8. Also I noticed that those are the first four and last four in the firing order (any correlation? what could cause that?). The cap is new but maybe it was weak or defective so it didnt last very long. I have had my hand on it quite a bit and never got shocked though.
So I thought the plugs might be fouled and I replaced them and the rough running improved. Now it was idleing much faster (600 before plugs and 1100 after new plugs), so I lowered the throttle/idle adjustment and then had to reset the timing. I checked the advance and it was reading 30 degrees at 2000 rpm which seems to be inline with what I understand it should be. So I am thinking the weak spark fouled the plugs. What could be causing weak spark on the 4 cylinders and good on the others? Could this be a bad coil or could that little light just be innacurate? ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: SNobsessed
Date Posted: September-07-2011 at 1:36am
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The coil fires all cyls - so logic rules it out as the problem. The cap could be bad somehow, not seated or off center - sounds like the rotor is not centered in cap well to me. It is strange that 1/2 of the rotor rotation has good spark & the other half is poor! ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: Jllogan
Date Posted: September-07-2011 at 11:21am
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I agree to that the fact that it is strange but it definitely has weak spark on half on the rotation. I have had that cap on and off several times, you would think it would be fit sometimes. Maybe I should see if I could wiggle it while its running. There is no chance the coil could be weak and just cant keep up with the spark or something. The other thing is the cap is new as of a few months ago so you wouldnt think that would be the issue.
Maybe the dizzy is worn or something, I had it out and had some people look at it and it seemed fine but maybe its not. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Bri892001
Date Posted: September-07-2011 at 12:14pm
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My guess is that the plugs already being fouled caused the the light to show weak for those cylinders.
The light is meant to show spark in the circuit, the plug has to fire to temporarily complete that circuit. I bet if you retested those cylinders with the light now, after replacing the plugs, it would show stronger. Your carb situation may have fouled the plugs to begin with. |
Posted By: Jllogan
Date Posted: September-07-2011 at 12:52pm
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I tested as soon as I started the engine and it still read weak. I suppose though that if the mix was bad in those cylinders you would never get good spark because of too much gas. The carb appears to functioning properly or at least acceptably now. Its hard to really tell how it is running now until I drop it in the water. It may be ok for a while but if it keeps fouling plugs thats an issue.
Is there anyway to really isolate and test the spark from the dist? Right now I am torn between carb issue or dizzy issue and I need to eliminate one. (in the back of my mind there is still a possible valve issue, but since its both sides of the engine I am ruling that out right now.) Summit Racing has a new points dizzy for 189 or a new electronic for 269, do I need RH or LH rotation I always forget. I know skidim has them but they are more expensive. I would probably throw on a new mallory coil too (so it matches). I need a way to pinpoint the dizzy though before I drop 300 bucks. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: SNobsessed
Date Posted: September-08-2011 at 12:26am
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Attach a plug wire & plug directly to the coil output (center terminal) & crank it over. You should get a good blue spark.
If your dizzy has any shaft play, or is rusty, time for a new one. I got a great deal from ebay, NIB prestolite electronic for $50. So there are deals out there if you are patient. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: lison
Date Posted: September-08-2011 at 1:40am
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This all sounds so familiar. I went through the same thing for an entire season. Plugs, points, condenser, cap, rotor, wires, rebuilt carb,drained all old gas, fuel filter, fuel separator, finally decided it had to be carberation and took carb back into carb shop and had it gone through again. Still the same lag, wouldn't idle right, quit at low speeds. Talked to the guys at skidim about all the bad gas we have here in MN and decided to bite the bullet and buy a new carb. Bolted it on and the Nautique has never run better. I think the small orifices in low speed get corroded and if the rebuilder doesn't soak it long enough to get those cleaned out, it doesn't fix the issue. Good luck. It's pretty frustrating. ------------- L Ison 1984 CC Ski Nautique 2001 351 PCM Ford Forest Lake, MN Crandon, WI |
Posted By: gun-driver
Date Posted: September-08-2011 at 10:09am
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If it's a fuel/air problem your plugs should tell you if thats the problem.
Have you checked your wires? 79 where are you!!!! |
Posted By: Jllogan
Date Posted: September-08-2011 at 11:29am
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yes,
wires are new as of 20 hours ago and I double checked them by switching them with the strong sparking cylinder. What do you mean by my plugs should tell me if its a fuel/air problem? is that why I have weak spark in the middle four cylinders? ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: gun-driver
Date Posted: September-08-2011 at 11:41am
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Your plugs tips will be black/carbon if rich, white/gray if lean.
If only one or some of the plugs are fouled/black and others are burning properly then it’s probably a ignition problem. |
Posted By: Jllogan
Date Posted: September-08-2011 at 11:59am
Ok thats good advice. It is definitely running rich, I can tell from the exhaust smell and the plugs are black. Some worse that others. The four outside corner cylinders (the ones that show good spark)are clean. So the good news is, I can say with good certainty the issue is carb or dizzy. The bad news is both those parts are expensive. Bummer. I will have time to fiddle again tonight, I plan to try and rule out the dizzy and re-adjust the mix screws. I am going to first check weak spark plugs outside the engine by holding to the block with the inline light tester to see if it is stronger, this will rule out rich mix choking spark. If that is still showing weak, I will then check the points gap on every lobe to check for wear there and inspect closer for any dizzy cam play or wear. If at any point these check out, I will then turn my attention to adjusting the carb. Thanks for all your help and advice. I am better armed to tackle this issue with your shared experiences and comments! ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: 8122pbrainard
Date Posted: September-08-2011 at 12:32pm
Justin, I have to ask why you didn't do a full rebuild on the carb. The needle and seat are key componemts. What else did you leave out? Did you soak the carb in a carb cleaner or just try to use one of the aerosol carb cleaners? Did you blow all the passages out with compressed air? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Jllogan
Date Posted: September-08-2011 at 12:57pm
I replaced everything that my rebuild kit came with. I didnt realize until later that those needed to be purchased separate from the kit. I didnt replace the floats (I have the black plastic ones) or the idle mix screws because these not included in my kit either. Everything in the kit went it. I did just use the aerosol cleaner and compressed air . If I rebuild again, I will soak over night. I was worried I would lose track of where things went if I completely dissassembled so I tried to work on it one side at a time and then put it back together right away. Also when I rebuilt the carb it was due to a fuel leak and not because it wasnt running right, so I decided if it wasnt broke and it didnt come in the kit I wasnt going to worry about it. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: TRBenj
Date Posted: September-08-2011 at 1:14pm
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Did you get a genuine Holley rebuild kit? Ive never seen rebuild kit that didnt include a needle/seat. I would think thats the #1 most important part to replace during a rebuild. ------------- |
Posted By: Jllogan
Date Posted: September-08-2011 at 1:29pm
Ya, it was a holley renew kit. It was at the beginning of the summer so maybe I just forgot or lost it somehow. I am pretty sure I didnt replace and didnt get one. Well jury is still out on carb, seems to be better now. If I can get it tuned Ill leave it. If not I feel more comfortable with where stuff goes as I have had it apart before. This time I will soak it overnight and replace everything!!! Someone also told me to add a little water remover to that carb cleaner, not sure if thats necessary. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: 89Martinique
Date Posted: September-08-2011 at 2:10pm
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try a new distributor cap my dads friends' boat ran like crap and had a loud knock turned out to be a hair line crack in the new distributor cap causing cylinder #7 to fire with every other cylinder we put the old one on it ran great ------------- Current Boats: 1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
Posted By: Jllogan
Date Posted: September-08-2011 at 2:14pm
Ya, if signs point to the dizzy it could be the cap, even though its new I suppose anything can happen. I bought a genuine PCM cap from skidim but I feel like the gasket is cheap and I have a hard time getting it to lay right. Its like the gasket is almost too small or something. ------------- http://correctcraftfan.com/diaries/details.asp?ID=5792&sort=&pagenum=1" rel="nofollow - 1986 Ski Nautique 2001 |
Posted By: Bri892001
Date Posted: September-08-2011 at 3:26pm
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Make sure your rotor is all the way seated. If it's sitting to high, you might not be getting the cap all the way down.
I remember this old thread http://www.correctcraftfan.com/forum/forum_posts.asp?TID=19567&PID=250303&title=distributor-cap-carbon-pill-issue - http://www.correctcraftfan.com/forum/forum_posts.asp?TID=19567&PID=250303&title=distributor-cap-carbon-pill-issue . Lunchdog was having trouble with the spring that holds the carbon pill from the cap down onto the top of the rotor. Just another thing to check. |
Posted By: eric lavine
Date Posted: September-09-2011 at 9:41am
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if the gas is not spraying (atomizing) and its streamimg, this will cause a rich condition. the venturi effect should atomize the fuel, just like a paint spray can, when atomized the flashpoint is lowered, you should get a nice atomized spray down the throat ------------- "the things you own will start to own you" |
Posted By: Luchog
Date Posted: September-09-2011 at 4:17pm
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lunchdog???? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: Bri892001
Date Posted: September-09-2011 at 4:51pm
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LOL, my eyes always read your name that way.
Did that the new spring and button fix your dist cap issue from before? |
Posted By: kapla
Date Posted: September-09-2011 at 5:35pm
hey dog!! let´s have some lunch!!!   tomorrow if you happen to be in BA don´t miss my BD barbecue!!!------------- <a href="">1992 ski nautique |
Posted By: Luchog
Date Posted: September-09-2011 at 9:28pm
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Brian, yes, the erratic timing problem went away with the new spring, later that same cap had moisture issues and put and old one back on with the "improved" spring and it's been working flawesly since. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: DrCC
Date Posted: September-10-2011 at 12:32am
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Man, That sounds good!!! BB-Q at BD boys house tomorrow!
Have not read the entire thread, but, have you checked for water in the tank? You don't have to drain the whole tank to remove the water off of the bottom. Whenever I suspect fuel issues, that's where I begin. |
Posted By: Jason
Date Posted: September-10-2011 at 1:56am
| There shouldn't be any fuel spraying into the body at idle. You said that when it started it was idling at 200. You had to crank up the idle screw to get it to 600. I'm no Dolley expert but this tells me that your idle circuit is blocked and you are having to use your primary circuit to get it to run. Fix your known issue, your carb, then move on to other potential issues like your spark. More than likely there rated by having rich mixture. I dealt with this issue and had my car rebuilt two times in a row then ended up buying new and never looked back. By the way red flags are flying with a kit not having a replacement float bowl needle valve. |