351w no spark issue
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=50748
Printed Date: November-22-2024 at 3:05pm
Topic: 351w no spark issue
Posted By: DockDoc
Subject: 351w no spark issue
Date Posted: July-08-2022 at 2:36pm
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Took the boat out for a ride a couple days ago, started up and ran beautifully as usual. Anchored out and swam for a couple hours then tried to head back and wouldn't start. Starter is firing / cranking but the motor doesn't even sputter, just cranks and cranks. Had to get towed back in. Did some troubleshooting today and confirmed it's a spark issue - i.e., no spark. The coil is probably an upgraded one, as whoever installed it bypassed the ballast resistor, so it's getting straight 12V, for whatever that's worth. Don't really know how to test the coil. I peeked under the distributor cap and the ignition module is looking pretty worn out / corroded. Not sure if that's the culprit. Not really sure where to go from here... seems like it's probably either the coil or the ignition module. Don't know how to test them though. Any tips, other suggestions etc? ------------- 1993 Sport Nautique PCM 351w, no ProTec |
Replies:
Posted By: KENO
Date Posted: July-08-2022 at 8:24pm
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You should probably mention what kind of distributor and module you have if you want any good, specific type information. Since it was a Protec replacement and it sounds like you have a separately mounted coil, I'll guess it's a Mallory distributor with a MBI magnetic breakerless ignition module in it since that was the replacement.in the protec delete kit. A couple of quick general checks would be to test the coil with a multimeter and you should have about 1.5 or so ohms between the positive and negative terminals Then check between the positive terminal and the coil wire tower in the middle of the cap and you should see around 8500 ohms or a high number like that. If it's not an auto ranging meter, make sure you're selected to an appropriate scale to give you a reading  Then using the multimeter or a test light with one lead hooked to the coil negative terminal and the other to ground, watch for the voltage to fluctuate from about 12ish down to zero ish and back up again as you turn the engine over or in the case of the test light, it will get dimmer and brighter as you crank the engine over. If it doesn't show any fluctuation and stays at about 12 volts or zero volts (or the test light stays solid on or solid off) and your coil tested OK earlier, then it means your module isn't working. Kinda general, but with no info on what you have, it's kinda hard to say much more.
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Posted By: DockDoc
Date Posted: July-08-2022 at 9:59pm
Sorry I don’t know exactly but I think it’s a prestolite distributor. Don’t think it was converted from a protec. Appreciate those suggestions ------------- 1993 Sport Nautique PCM 351w, no ProTec |
KENO wrote:Posted By: KENO
Date Posted: July-09-2022 at 6:20am
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After all the Protec talk in a couple of your old threads, I thought it was converted.................that'll teach me to think Here's a picture of a Prestolite with the cap and rotor removed showing the module  The checks mentioned previously should work for you to see where the issue is. Also before checking any of that stuff, check that you have about 10 to 12 volts at the coil positive terminal with the key in the Run position. In the picture above, there should be a .010 gap between the teeth and the black sensor, but I doubt that just decided to get loose and change on you. If you end up needing a new module, those aren't made anymore, but Pertronix makes a module for it. |
Posted By: DockDoc
Date Posted: July-09-2022 at 7:47am
Thanks! That is what I have for sure. So dumb question but does this mean I don’t have points? In other words that module replaces the points system? ------------- 1993 Sport Nautique PCM 351w, no ProTec |
Posted By: KENO
Date Posted: July-09-2022 at 8:12am
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Yep, no points, the module does the job of the points
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Posted By: stepper459
Date Posted: July-09-2022 at 9:35am
I talked with DockDoc just now. Here's the module I have:   Which I ordered when I suspected this one was bad (it sure looks the same to me...)  I'm happy to send that along or you can get one from the internet according to Ken's advice to me a few weeks back:
------------- All boats are sinking, it's just a matter of how quickly. |
Posted By: DockDoc
Date Posted: July-09-2022 at 9:47am
Yeah that module you show there in your pic looks identical (except mine looks badly corroded). ------------- 1993 Sport Nautique PCM 351w, no ProTec |
Posted By: uncle-buck
Date Posted: July-24-2022 at 6:26pm
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DockDoc, don't know where you are in the process. If you haven't secured a new ignition module for your boat's distributor, you may want to give serious consideration to upgrading it to a D.U.I. Did it last year, with lots of help from Jonny Quest, and it totally transformed the performance of my 1990 SN. Have had the boat since it was new and and it literally runs like it did when it came from the factory. |
Posted By: DockDoc
Date Posted: July-31-2022 at 12:07pm
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Just to update this post... it turned out to be the coil! As Keno mentioned I checked with an ammeter and found that the resistance at the large connector going out to the distributor cap was roughly half what it should be (~4500 vs 8500). Slapped a new coil on and it fired right up. Of course, stepper459 had already sent me that pertronix kit and I really didn't like how the old one looked so I swapped that out along with a new distributor cap and rotor just for good measure. Re-timed it and it starts and runs like a top! Appreciate all the help as usual.
------------- 1993 Sport Nautique PCM 351w, no ProTec |
Posted By: KENO
Date Posted: July-31-2022 at 3:57pm
But now I see you have other stuff to worry about
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Posted By: Jonny Quest
Date Posted: July-31-2022 at 5:07pm
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Well done. A "bad coil" is a frequent problem in these older engines. Not surprised you got bit. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |