Print Page | Close Window

Engine Stutter and rough running

Printed From:
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
Printed Date: September-22-2023 at 2:44pm

Topic: Engine Stutter and rough running
Posted By: asuj158
Subject: Engine Stutter and rough running
Date Posted: May-22-2023 at 9:29pm
Hey everyone! Looking for some help. Bought a 1989 Ski Nautique 2001 and ran great when I bought it at the beginning of the season. Now I’m having issues with starting, it won’t start right up without revving it or starting multiple times (4-6 times). Also it will misfire under medium load, not WOT. Sounds like a tin pinging sound. To go along with it the boat now only gets up to 35mph WOT and seems to run rougher and louder before. Any tips or things to check would be MUCH APPRECIATED. Thanks guys.

Posted By: Wilhelm Hertzog
Date Posted: May-23-2023 at 5:17pm
Check ignition timing?

1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light.

Posted By: asuj158
Date Posted: May-23-2023 at 7:06pm
I did some more investigating… and the previous owner didn’t tighten the spark plugs. 5 were loose. 1 had the tip missing. Changed them out. Gapped to .035 and running a ton better. Still doesn’t feel 100%. Put a vacuum gage on the PCV and it’s around 20. Vacuum leak? At WOT it gets hot and also only gets to about 39mph

Posted By: asuj158
Date Posted: May-23-2023 at 7:47pm
I jinxed it. One boat had been running a while it started misfiring a ton under load

Posted By: asuj158
Date Posted: May-23-2023 at 8:12pm
Also another symptom is the coil is INCREDIBLY hot

Posted By: uncle-buck
Date Posted: May-23-2023 at 11:37pm
Sounds like an ignition system issue. Others with better diagnostic skills will probably chime in.

I have a 1990 SN that exhibited similar symptoms a couple of years ago.

Replaced the ignition system with this:" rel="nofollow -  , replaced the spark plug wires, rebuilt the carburetor, replaced the carburetor spacer gaskets, opened spark plug gaps to 0.055", and reset ignition timing. The boat has run like new since then.

Good luck with yours.

1990 Ski Nautique (original owner)
PCM 351W with D.U.I.

Posted By: asuj158
Date Posted: May-24-2023 at 1:14pm
I think maybe I have a bad resistor? I checked voltage at the resistor and the coil. It’s jumping all over the place 0 up to 17-18 volts

Posted By: MrMcD
Date Posted: May-24-2023 at 3:43pm
The missing tip of a spark plug tells me you have detonation going on which can damage the engine.  As advised several posts back check your Timing.  To much timing will melt the end off a spark plug.   Sounds like you have other issues also but Timing makes a difference on performance.
Detonation can break pistons, Piston rings, Scuff cylinders, blow head gaskets and melt spark plugs so don't overlook this one.


Posted By: KENO
Date Posted: May-24-2023 at 7:08pm
Originally posted by asuj158 asuj158 wrote:

I think maybe I have a bad resistor? I checked voltage at the resistor and the coil. It’s jumping all over the place 0 up to 17-18 volts

If you have 18 volts anywhere on the boat, you have some voodoo and black magic going on...............or your alternator is defective and putting out 18 volts. The alternator on an 89 has an internal regulator, so if you take your multimeter and check output voltage while the engine is running (one wire of the meter to ground and the other to the terminal on the back of the alternator with the big Orange wire  on it)...., you should see 13 to 14 ish volts and the same at the battery if you put the meter on the battery.

So check those readings and that'll tell you if the alternator is bad and putting out too much voltage.

If you want to check your resistor, put your meter on a low scale like 20 ohms and clip one wire to one terminal of the resistor and the other to the other terminal. 

You should see about 1.5 ohms resistance unless there's a jumper installed between the 2 terminals.

That jumper is installed for most electronic ignition conversions and with it installed the resistance between the 2 terminals will be zero.

Now speaking of ignition systems, do you have the original points system or maybe an electronic conversion.

If you really have 18 volts to the coil when running that's bad for the points and bad for an electronic ignition too and you'll burn up a coil or set of points or an electronic module. Wink

You can get your stuttering and rough running as things are in the process of failing

PS   .......You mention 20 inches of vacuum at idle ............that's about as normal as you can get.

Posted By: wayoutthere
Date Posted: May-24-2023 at 7:43pm
Welcome aboard asuj,
your on the correct site and from these guys, you will get some of the best technical info and guidance to help solve any issues that may pop up.

What's the odds the mechanical advance weights/springs are stuck open/partially open causing the hard start and detonation ?

Did that year have felt under the rotor and isn't that for lubricating the counterweight springs ?

Posted By: asuj158
Date Posted: May-25-2023 at 2:53pm
The timing was definitely off. Once I fixed it there was still detonation going on. I replaced the coil which seems to have helped tremendously. Going to replace the cap, condenser, and the wires as well just to be safe.

Posted By: MrMcD
Date Posted: May-25-2023 at 3:03pm
Setting your timing at idle is important but more important is checking your timing at RPM, see how it advances and how far it advances.
It should advance very smoothly as you increase RPM from idle to 4,000.  It should advance the same each and every time you try.    
You are looking for total advance somewhere around 34-36* and then it should stop advancing.
Most like to see full advance by 3,200 RPM, some of the older systems keep advancing all the way to 4,000 RPM.   If your distributor advance springs are tired or rusted you might be getting full advance much lower in your RPM curve causing this detonation problem.   
If you have or can borrow a Dial Back timing light it makes tracking your timing advance very easy so you can verify what you have before buying any more parts.  
Boat distributors see more moisture than automotive distributors so rusted advance plates or springs are pretty common.


Posted By: asuj158
Date Posted: May-25-2023 at 3:12pm
It was definitely rusty down there. No broken springs or seized weights. Should I still replace them?

Posted By: KENO
Date Posted: May-25-2023 at 7:53pm
Originally posted by asuj158 asuj158 wrote:

The timing was definitely off. Once I fixed it there was still detonation going on. I replaced the coil which seems to have helped tremendously. Going to replace the cap, condenser, and the wires as well just to be safe.

So how are your voltages ?

If you're replacing the cap and condenser, why not replace the rotor and the points at the same time?

What was the timing before and after the adjustment?

Posted By: asuj158
Date Posted: May-25-2023 at 8:49pm
I need to double check them. However I ordered a tune up kit that will include the cap and points as well. Ordered wires too

Posted By: Trader144
Date Posted: May-26-2023 at 8:23am
I have a 1988 ski nautique 2001 with a 351w and I am having the same issues. I reset the timing and changes the springs but I am not getting any advance at 4K from in neutral out of the water. At 4K i am at 10 degrees to the left of zero when facing the rear of the boat, same as idle.

Prestolite bolt on distributor, also charged out the electronic ignition to a new Pertronix. The weights seem loose enough but I cannot move them due to the plastic guard holding them in place:

I have been told I do not need to test it in the water.

Are there any other options? Or is a new one in my future?

Posted By: MrMcD
Date Posted: May-26-2023 at 11:37am
With no advance I am surprised you can reach 4,000 RPM on the water.
Mechanical advance works on RPM, so it does not matter if you check on the trailer or on the water.
You should also be able to remove the distributor cap and grab the rotor with your hand and gently rotate it from the idle stop to full advance, let go and have it rotate back to the idle stop.   This is not much movement, but you should feel it move and go back when you release it.   If it does not move or if it moves but does not rotate back something is interfering in normal operation.   You need to investigate.


Posted By: KENO
Date Posted: May-26-2023 at 12:16pm
Trader 144, I'd be curious what you used for advance springs in the company and part number or a link 

You could have the right ones ..... or  springs that are way too stiff.

If you want to get that plastic advance limiter off, you have to remove the little spring in the center of the shaft. It might have a piece of felt over it, hiding it from view

I call it the "spring from hell"  Wink

It's hard to remove and equally hard to reinstall (and pretty easy to lose if it gets away from you in the process..

It's a little circular wire thing and you can barely see it in the picture below." rel="nofollow">

Posted By: Trader144
Date Posted: June-02-2023 at 7:35am
Thank you to everyone. I think my problem has been fixed and the boat now planes out and gets out of the hole well.

My Nautique started bogging down about 3 years ago, and 2 years ago it wouldn't pull a skier out of the water very well. Gas mileage was getting really bad. After storage last year it ran extremely bad, pumping blue/black smoke out the back and burning 5 gallons in about 30 minutes and I couldn't take it out (engine cooling was still working).

I tried fixing small things one at a time (fuel filter, fuel pump, fuel line, car rebuild, new ignition setup, rotor, cap, etc) and nothing worked. 
Here is what I wish I would have done in the first place to possibly save $1500 in unnecessary parts and labor, and a year off the water in case it helps anyone (stop where it fixes the problem). It would have taken less than 2 hours for an inexperienced person.

1. Check and replace/regap spark plugs, make sure spark plug wires are in good condition and have good connectors
2. Check the firing order of spark plug wires on the distributor cap by referring to the user manual
3. Get a $35 timing light
4. Spend 30 minutes to learn how to analyze timing at idle and at 3k rpm. It is really that easy.
5. Spend 10 minutes checking the timing and marking with chaulk.
6. Reindex the distributor (see video below)
7. Adjust the distributor advance if the above do not fix the problem - 45 minutes; it is not difficult. Mark the distributor cap, wire order on the cap, and draw a line from the distributor shaft to the engine block to identify the distributor's position before you change anything. If the timing doesn't change when rpms increase (e.g. go from 10 degrees before top dead center at idle, to 24 degrees before top dead center at 3k rpm), that means it is not advancing and the weights are not expanding at higher speeds, start with just replacing the springs ($7-$15 and about 20 minutes of time).

This would have told me that my 20+ year old distributor (a) timing was off, and (b) it was not advancing in timing. That would either be a fast and cheap repair (e.g. new springs) or a more costly replacement . My old distributor had a magnet sleeve under the rotor which is basically a case that holds 8 magnets and sits on the distributor shaft. I noticed the magnets had come out of the sleeve, and only found 4 of them so I tried replacing the ignition. The new ignition setups do not use magnet sleeves anymore. Did not fix it.

Excellent videos by the team:

I ended up replacing my distributor and spark plug wires with a new one. It was very expensive but my old Prestolite one has been through years of salt and fresh water and I was concerned the lost 4 magnets were doing something to prevent the weights from expanding. The DUI distributor (bad name) seems to be a lot more powerful, and I followed all of the instructions. 
Here is the one that fit my 1988 Ski Nautique 2001 351W RH rotation. The team at skidim was very helpful and gave me a ton of instructions for free." rel="nofollow -

I took my tools on the water and had to make some slight timing adjustments (e.g. 2 degrees) vs out of the water to alleviate rough running.

Happy to provide more info it it helps.


Posted By: KENO
Date Posted: June-02-2023 at 8:54am
Your 4 missing magnets turned your engine into a 4 cylinder engine, since as the magnets pass the sensor in the  module they tell it when to fire and send spark to a cylinder so only 4 cylinders were firing. Wink

The magnets have nothing to do with the weights. You probably had springs that were too heavy.

Sounds like you had other distributor issues anyways that you weren't gonna get past

Print Page | Close Window