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86 SN Breaking Up Under Load

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blowrie326 View Drop Down
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    Posted: July-08-2024 at 10:01pm
Hello all, this is my first post so i hope i am doing this right. Looking forward to contributing and learning

So i have had a 1986 SN 2001 since 2017 and since then i have been fixing different problems as it sat for years before i rebuilt it.
My latest issue is the boat breaking up under load. After the engine warms up a bit it will start to miss and break up intermittently for a few second and then slowly catch back up and run normal.
It will rev up real quick in neutral with no hesitation. just under load, especially when trying to yank up a skier.

Some background on the latest diagnosis/parts:
Brand new Holley marine carb that runs real smooth. Put an inline fuel filter in as well.
Brand new plugs and wires last year (correct prestolites and wires from nautique parts) 
new coil last year - is producing 12.5 volts to + side when key on
New cap 3 years ago
It has been converted to EI with a breakerless ignition from nautique 3 years ago. It is not being passed through the ballast resistor as i fought with this as nautique says it needs to be used with a resistor but then contacted the manufacturer and they said it couldnt be used with a resistor as it need 12V at all times.

So basically i have replaced all fuel and electric and still am running into issue with misfiring and am all out of ideas.
I read that a faulty tach could cause the issue except i disconnected it from the coil and it still remains an issue

Im starting to think the breakerless igntition is faulty. i thought about replacing or going back to points. I believe the timing is at 10-12 degrees as well

Any information is helpful. Thank you in advance!!
B. Lowrie
86' Ski Nautique 2001
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 7:53am
If you have the points plate with everything mounted to it, putting the points back in isn't hard and will at least tell you something  and you'll get to check/verify the timing when you do this  Wink

This must be a Prestolite distributor with a clip down cap?

Pertronix electronic conversion?  Part number for the kit?

What's the coil?

Cap and rotor look to be in good shape?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote blowrie326 Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 10:40am
I may still have a set of points laying around I can throw back in. I’ll have to look.

Yes this is a prestolite clip down distributor

The breakerless ignition and the coil are from Nautiqueparts.com not sure what brand they’re but I can go back and look. I certainly didn’t cheap out on them. I did test the coil and it seems to be putting out what it should at an idle. About 12.5 volts

The cap looks good, rotor isn’t used with the breakerless ignition. It just senses off the lobe on the distributor shaft
B. Lowrie
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GottaSki Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 10:58am
Must have a rotor. perhaps you mean reluctor.

Check the shaft for radial play, and confirm the air gap is not more than spec when you put some pressure on the shaft.
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 12:51pm
Originally posted by blowrie326 blowrie326 wrote:

I may still have a set of points laying around I can throw back in. I’ll have to look.

Yes this is a prestolite clip down distributor

The breakerless ignition and the coil are from Nautiqueparts.com not sure what brand they’re but I can go back and look. I certainly didn’t cheap out on them. I did test the coil and it seems to be putting out what it should at an idle. About 12.5 volts

The cap looks good, rotor isn’t used with the breakerless ignition. It just senses off the lobe on the distributor shaft

What you really mean to say is that the magnetic ring used in some Pertronix kits isn't used and that your kit is a Pertronix 91581LS or maybe the cheaper 1581LS. Wink

The 91581LS has a Red magic box and the 1581LS has a Black magic box.

It uses the original rotor and the magic electronic circuitry in the little box senses when a lobe passes by to make a spark that the rotor transfers to the terminals in the cap as it passes each terminal.

Click on the link below, it most likely what you have.


The coil puts out lots of volts like 20,000 to 50,000 or so, what you're measuring is the input voltage to the coil from the ignition switch, which is basically battery/alternator voltage. The coil steps it up to the high voltage working in conjunction with the electronic module that grounds and ungrounds the coil as the lobes pass the sensor in the magic box.

Pertronix says to eliminate the ballast resistor just like you did and it works good that way.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GottaSki Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 1:14pm
I may have one of those kits new in box available, i don't have a future need for
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."

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Post Options Post Options   Thanks (0) Thanks(0)   Quote blowrie326 Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 2:18pm
You’re right I have the cheaper one with the black box that looks identical to this pertronix one.

I was just talking to a coworker and mentioned he had an old truck that was missing when he got on it and it was timing. I know it was mentioned earlier in that thread. But he said that it was the “total” timing when the engine was at 3400rpms and not the idle timing.
I am not sure what total timing would be on these 351W. Does this sounds like a good place to start after double checking the cap? Versus buying a new pertronix
B. Lowrie
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Post Options Post Options   Thanks (0) Thanks(0)   Quote blowrie326 Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 2:29pm
I wonder if it is a grounding issue? Maybe I need to clean the baseplate and inside housing of distributor shaft where the baseplate sits? It is the original shaft and housing. I just don’t feel like spending $500 on a whole new setup like the below link but hey if that means all my problems are gone I might have to

https://nautiqueparts.com/electronic-distributor-5-8l-breakerless-ingitor-ii-for-351-ford-engines-with-standard-rotation-left-hand/
B. Lowrie
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 5:12pm
To check Total Timing on a boat is not difficult since they do not run a vacuum advance on Boats.

Hook up your timing light.  Engine at idle timing might read 11* I think you posted.  Advance the throttle slowly while watching the timing mark.  You should see it advance or move as your RPM's increase.  
Keep increasing RPM while watching the timing marks, it should continue to advance.  Old distributors might continue advancing to 4,000 RPM, newer ones are fully advanced by 3,400 RPM.   You want to know that yours does advance, how much advance it offers.  20* or so is normal, maybe 25*.   Your Total timing would = the setting at idle + the amount your distributor advances.  Ideally you will want the two to add up to 34* approximately.   A set back timing light makes this job very easy if you have one.   IF your timing marks do not go all the way up to see 34* you might need to measure out and add another mark at 34*.  Be careful to measure exactly.   At 34* it will run perfectly, at 38 you might start damaging parts or blowing a head gasket.
If your timing is accurate and smoothly advances each time you have ruled this out.  If it is not moving your distributor is rusted inside and needs to be cleaned up, maybe install new advance springs.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 7:34pm
Here's a link to an old thread with some "representative" advance numbers from idle up to full throttle, partway down the first page.

It'll give you an idea what you're looking for.

When you installed the Pertronix kit you would have been looking at the springs and weights at that time.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 7:50pm
Originally posted by blowrie326 blowrie326 wrote:

I wonder if it is a grounding issue? Maybe I need to clean the baseplate and inside housing of distributor shaft where the baseplate sits? It is the original shaft and housing. I just don’t feel like spending $500 on a whole new setup like the below link but hey if that means all my problems are gone I might have to

https://nautiqueparts.com/electronic-distributor-5-8l-breakerless-ingitor-ii-for-351-ford-engines-with-standard-rotation-left-hand/

Umm.........you don't want to buy that distributor in the link for your engine.

You have a Reverse Rotation aka backwards rotating Right Hand Rotation engine in your boat assuming it's original to the boat.

The one in the link is for a Normal Rotation, Left Hand Rotation engine like in a Ford truck with a 351.

You can do a whole lot of reading here on CCF about reverse rotation engines and the difference in cams, cam gears and distributor gears

To tell which way your engine rotates in the marine world, you stand behind the engine, looking at the flywheel and the engine turns Clockwise, it's Reverse Rotation. Or if you want to look from the front, if the pulleys and belts are turning Counter Clockwise, it's a Reverse Rotation engine.

A normal rotation engine is bass ackwards from that 

It can be real confusing the first time you're figuring this out  Wink
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Post Options Post Options   Thanks (0) Thanks(0)   Quote blowrie326 Quote  Post ReplyReply Direct Link To This Post Posted: July-09-2024 at 8:31pm
Alright I just got off the boat and what I did was double check the timing and at idle it was at about 8° on the stock white mark. I advanced it to what looks to be about 12-14° (little tough to get a solid read) warmed it up and went for a ski. It pulled much better and didn’t miss but does still have a very slight hesitation that lasts a second in the middle of the pull. I didn’t notice it behind the boat but the driver did and when I gave it a dry start I noticed it but it doesn’t sound electric anymore. It sounds like the carb is sucking just a little too much air and then pulls great. So as far as I’m concerned it fixed the problem!
Can’t thank everyone enough!
The slight hesitation doesn’t bother me too much. It’s almost negligible. It’s a brand new carb.
Hopefully this issue is done with and I’m not getting too excited prematurely!
B. Lowrie
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 63 Skier Quote  Post ReplyReply Direct Link To This Post Posted: July-10-2024 at 12:42am
Do you have an anti-siphon valve on the fuel hose at the gas tank?  If so remove it, clean it, a sticking valve can intermittently starve an engine for fuel.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote blowrie326 Quote  Post ReplyReply Direct Link To This Post Posted: July-10-2024 at 10:46am
Interesting thought. I’m sure there is one and it certainly has not been cleaned in a long time if ever. But wouldn’t there be plenty of fuel in the bowls of the carb already from just idling to when you hammer it to yank up a skier?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 63 Skier Quote  Post ReplyReply Direct Link To This Post Posted: July-10-2024 at 11:15am
Maybe.  I'm thinking like others that ignition is the more likely culprit but on any of these boats cleaning the anti-siphon makes sense so worth doing so anyway.  On mine the symptom was losing power when increasing to higher speed, like might be running well at 28 but throttle up to 34 and surging would begin, so agree it's probably not related to your stumble on sudden heavy load.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: July-10-2024 at 11:31am
So, we know your base timing was increased a little and the boat runs much better.  Not great but much better.  With the timing light hooked up did you check the Total Timing by revving the engine while watching the light?

Marine distributors pick up moisture in normal use.  The distributor weights can rust and stop working properly or the springs inside rust out and break.   If it does not advance properly you can be down 40% on power.   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote blowrie326 Quote  Post ReplyReply Direct Link To This Post Posted: July-10-2024 at 2:13pm
Yes the total timing when revved up was about 34°. I can check the tank valve too
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MrMcD Quote  Post ReplyReply Direct Link To This Post Posted: July-10-2024 at 2:46pm
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