Help! Runs like crap when warm! |
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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Posted: July-28-2013 at 11:49pm |
Hi guys,
Been a slow start to the boating season for me. 1973 with a 351 PCM. After a few good trips, our last couple have been bunk. we have had an issue where the boat runs great at first (starts right up, smooth acceleration, full power) but after a little while on the water and a few runs, things go down hill. The boat will either stall or stumble out of the hole and will eventually get to a point where it will run rough and the revs will cap out at around 2500 rpm. After cooling off, things are back to normal. We had it in to a shop after the first bad trip where they replaced the cap (apparently the wrong cap was on there), tinkered with the timing and replaced a few resistors. We had her out again today, and bam, same problem. Huge piss off. Boat always starts without issues, even when it is running poorly, and idles well. It just doesn't like to be revved or put under any sort of load. Any advice is appreciated! Derek |
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1973 Nautique 351
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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There seems to be a string of coil problems lately. Search the site and you'll see a few threads.
Yours sounds like a classic case. What happens is the coil overheats and starts performing badly. Most typically say an oil filled coil laying on it's side will cause you problems. I'd get an epoxy filled one. See if Zach at N3 Boatworks (Banner above) can get one for you. If not Skidim etc. will have it. I think Snobsessed recommends the Blaster 2 Epoxy filled coil as a good reliable one. |
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storm34
Grand Poobah Joined: November-03-2008 Location: Dexter Iowa Status: Offline Points: 4492 |
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We've been battling the same problems with Pat's 84 although it won't start after it dies.
Replaced the coil a few weeks ago when it happened and that seemed to solve the problem but it happened again when we got back from GL. Going to replace the resistor and see what happens. Zach and I are thinking the same as Brian. Coil (new) gets hot and fails due to too much current from the resistor. If that doesn't solve the problem I'll get in another boat and go |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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Chris has the luxury of parking a boat and getting in another if need be ;)
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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My alternative is a 12 ft alumnium with an 8 hp outboard. Might be able to drag a kid around on a knee board
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1973 Nautique 351
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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Going to try replacing the coil (can't hurt, the one in there is old).
I have a breakerless setup, and it looks like the resistor is still there. Could this be part of the issue? Or would the resistor be a non factor? Opinion on the MSD 8222? (epoxy filled) |
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1973 Nautique 351
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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The resister could be a factor. But usually these problems occur when the resister is taken out of the loop after a breakerless conversion etc. Are you sure the coil/dizzy is wired through the resister, or is it just hanging out?
How long ago was the breaker-less conversion done? Has it ever run good since? What brand conversion kit did you use? |
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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Conversion was done before I owned it and the resistor is wired in.
Boat has run strong up until this point. |
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1973 Nautique 351
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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Resistors can go bad. Buy yourself a multimeter and check input and output voltage.
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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Have a meter. Before googling, what reading am I looking for on either side?
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1973 Nautique 351
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diggit
Senior Member Joined: August-12-2012 Location: Minneapolis MN Status: Offline Points: 135 |
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I had the exact same running conditions you describe and in my case I eventually discovered I had no ballast resistor in the circuit. Wired one in and it's been golden ever since.
They're cheap so might be worth just replacing it. |
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'93 Ski Nautique Black/Teal
'77 Ski Nautique. Loved it. Let it Go. |
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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UPDATE: Replaced the coil with an MSD 8222. Had to wait for the matching resistor. Ran it with just the new coil, same thing.
Added the MSD 8124 resistor...ran better, but same thing. I then realized that the ignition wire was running right to the + on the coil. Moved that down to the resistor and had a great afternoon on the water today. Also some of the rng terminals were looking like they had seen better days, so I replaced those as well. I think I have this figured out! |
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1973 Nautique 351
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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One more question...The red wire from the dizzy is still straight to the coil...should this run through the resistor as well?
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1973 Nautique 351
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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Hmmm, if you mentioned the name of the ignition conversion, I missed it.
With the Mallory "Magnetic Breakerless Ignition Module", the answer is no. That red wire should not be fed through the resistor. Here's the figure from the Mallory installation instructions. They show it going to the ignition side of the resistor, but the point is, it needs a 12V ignition feed. |
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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Def not a Mallory....I'm guessing (because I didn't install it) that its a PerTronix.
If I have it directly to the coil, it is getting the reduced voltage, correct? Just not sure if it needs to full 12V or not. |
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1973 Nautique 351
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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I think it still needs 12V. See "Ignitor 12 V negative ground" on the Pertronix Installation Manuals page.
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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> "If I have it directly to the coil, it is getting the reduced voltage, correct?"
Yes, and that's not what the diagrams show. You need to identify the make and model to confirm all of this, though. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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As far as I am aware every electronic ignition conversion needs a full 12v feed to the distributor hot wire to operate properly.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Zach the old prestolite? only had two wires purple and black. Purple to the + side black to the - side. If you run a resistive coil remove the ballast resistor if your coil is non-resistor you need to run the ballast resistor. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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Paul, The old ones ran the purple as a resisted feed? Now that you mention it that 82 we just tuned did have a purple wire coming from the distributor.
Above he was talking about how he installed the resistor that MSD provided?? Then also ran the regular resister too? Sounds funny. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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delovett
Groupie Joined: June-02-2012 Location: Burnaby Status: Offline Points: 67 |
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Only one resistor (the MSD one). Used it to replace the old one.
Right now I have ignition, alt and choke to the hot side of the resistor. From that, one wire to the positive side of the coil. From the dizzy, red wire to the positive on teh coil, black to the negative. |
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1973 Nautique 351
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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Ahhh gotcha I wasn't reading everything correctly! Good deal.
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mousecreek
Newbie Joined: February-07-2009 Location: United States Status: Offline Points: 17 |
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Don't overlook the fuel filter. Replacing the fuel filter resolved identical issues for my 79 SN.
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jblocal
Senior Member Joined: September-06-2010 Location: Stuart, Florida Status: Offline Points: 203 |
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Ok so I'm a little confused on the Mallory wiring. For a year I been running my Mallory distrib with no resistor. My coil that came with the Mallory distributor from ski dim says no external resistor required right on it. The wiring diagram here shows the coil + going to resistor side. So do I use resistor even though it says no external resistor required on coil?
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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This is from the Mallory website, instructions for Unilite electronic dizzy:
IMPORTANT Before installing the UNILITE® Distributor, make sure that your vehicle is equipped with an ignition ballast resistor (or loom resistance wire) in the wire between the ignition switch and the coil (+) terminal. Check a service manual for your vehicle to locate the ignition ballast resistor (or loom resistance wire). If your vehicle is not equipped with an ignition ballast resistor, install a Mallory Ignition Ballast Resistor Part No. 700 in the wire between the ignition switch and the coil (+) terminal. Failure to use an ignition ballast resistor will eventually destroy the UNILITE ® Ignition Module. |
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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The important question is how does it run? If it runs well and doesn't give you any problems I'd tend to leave it alone. |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6150 |
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I like Points . But really I was always under the impression the red wire on a Mallory was 12v (it being red). Apparently not. Makes more sense for an easy hookup on a points conversion not having to change anything about the setup. I should make PCM supply instructions with the new distributors.
Now that I sit here and think about it all of the conversion kits for the protec boats I believe come with a ballast resistor. I will have to check and confirm that. |
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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It is 12V. It's too easy to misread the Mallory diagram the way they show it. The red wire to the Mallory distributor wire harness is wired to the 12V ignition switch side of the ballast resistor. The diagram shows it connected at the pole on the resistor, which is apparently confusing (I had to look twice when I first read the diagram). |
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Georges82
Newbie Joined: August-11-2013 Location: Bellingham WA Status: Offline Points: 10 |
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I have to jump in on this topic because I have the same coil overheating problem with my 1982 SN 2001. I have been reading a lot of posts about different issues that have helped me a lot.
I have resolved several ignition issues and finally decided to install a Mallory Unilite I got from Summit racing. I also bought a coil they suggested. The coil was #29217, oil filled with 1.4 ohm resistance, and it said NOT to use a ballast resister. The dizzy instructions plainly said to use a ballast resistor, so I called their tech support and they told me that a coil with 1.4 ohms or more of resistance does not need an external resistor. They told me to take it out of the system. So here I am, first trip to the lake, boat runs great, no hard starting issues, no idle issues, everything is good for about 35 min. when it starts missing and dies, wont start, paddle to dock (again). Take boat home, still wont start, put in spare coil I had at home and boom, starts right up. So I guess my question is what coil to use. I could not find a blaster 2 epoxy filled coil on the MSD web site. I found a epoxy filled blaster with .07 ohms resistance, which I believe would require an external resistor. Is this the one that SNobsessed is talking about? Before I got the Mallory Unilite I had a Pertonix igniter II with a flame thrower II coil and that coil cracked at the tower and left me paddeling after about 45 min of running. Thanks for the help |
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