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Old 08-11-2004, 06:07 AM
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hardycm hardycm is offline
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Engine stumbles at high speed

My '88 PS 190 developed a problem during a weekend trip (of course) recently. The problem is that the engine suddenly stumbles at high speed. The problem seems to be intermittent and doesn't happen at a certain place in the power band. Sometimes it happens while I'm cruising along, sometimes right when I pull a skier out of the water.

I'm not sure if its related, but for the past two seasons I've had a very slight, intermittent stumble during idle. Occassionally this will kill the engine, but not normally.

I'm leaning toward thinking this is an ignition problem, because whenever this happens I smell gas or see black smoke on the re-start (i.e. burning rich). I don't think its the carb - I rebuilt it last year and had no problems other than that slight stumble during idle.

Any thoughts of what all I should eliminate before installing an electronic ignition, and would that fix the problem if its an ignition prob?

Thanks,

Chuck
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Old 08-11-2004, 08:09 AM
atlps190 atlps190 is offline
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Boat: '92 Prostar 190 - 285 HO
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Question

Fuel filter? When's the last time you took a look at it or changed it? Bad gas? Sounds fuel related to me...
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1992 Prostar 190 - 1:1 285 HO
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Old 08-11-2004, 08:32 AM
Dan K Dan K is offline
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I second the fuel relation. Ignition is usually binary, it works or it doesn't. Bad fuel or a clogged filter will act this way sometimes.
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Old 08-11-2004, 10:39 AM
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NatesGr8 NatesGr8 is offline
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I've had a similar problem on a car of mine. It turned out it was just a loose ground connection where the ground cable attaches to the engine. However, the car was fuel injected and not carburated, just thought I'd let you know another possible problem location. So, I would check this after I checked the fuel situation. Good Luck!
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Old 08-11-2004, 10:46 AM
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When was the last tuneup, including plugs and wires(especially the coil wire)? I replaced coil wires on boats that had run 15 minutes before, then wouldn't even start. If it's flakey, you won't have complete combustion and it can kill and when it starts again, the unburned gas just passes through. Do you need to crack the throttle to get it to start?
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Old 08-11-2004, 12:54 PM
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hardycm hardycm is offline
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Yep, I was going to eliminate fuel filter and water separator first -- sounds like the consensus is fuel so I'll focus on that. As far as tune-up, new points & condenser 6 yrs. ago and new plugs about 3 yrs ago is all I've done. As far as the coil, is that part of the elec ignition package or separate?

Thanks for the replies.

Chuck
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Old 08-11-2004, 02:25 PM
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How many hours per year do you put on the boat? 6 years is a long time if you use it much. The wires take on moisture, then the silicone conductor gets brittle and cracks(unless they're solid wires), the whole inside of the distributor gets covered with condensation and corrodes, etc. If the lube on the fiber wedge that rides on the distributor cam dries up, that wears down and then the dwell changes(and not for the better). If the plugs have rusted into the heads, they won't conduct as well as they should and then there's no chance of the spark being as intense as it should be.

Yes, the coil is absolutely part of the electrical system, but if the points aren't adjusted correctly, the coil can't deliver spark with the intensity needed.
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Old 08-11-2004, 02:58 PM
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hardycm hardycm is offline
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Jim, I put 40-50 hrs per year on it. I took the cap off at the lake and looked at it -- there was a little corrosion on the electrodes, but not a ton. I do remove the plugs every year during winterization and they've always looked good -- no carbon rust on the threads, etc.

Your points about the wires are well taken though -- probably time for a new set regardless.

As far as the coil, my question is if I get a new electronic ignition system (the one everyone says is worth every penny), does that replace the coil, or is it something I still need?
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Old 08-11-2004, 08:59 PM
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The electronic ignition replaces the points and condensor, really nothing more. The coil is still needed. You need to check with whoever you get the ignition system from for the correct voltage to the module. I would think it should be 12V. The reason the points need approximately 9V is that they don't handle current very well without burning. The reason the crank lead doesn't go through the resistor is that during cranking, the voltage drops to a level that the points can handle. Then, when the key goes to the "run" position, the voltage goes through the resistor and the points are happy.
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Old 08-12-2004, 07:19 AM
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hardycm hardycm is offline
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Got it, thanks Jim. I checked the fuel filter and water seperator yesterday -- no sign of anything wrong. I draine about 2 C of gas out of the seperator and saw no sign of water. What's next? I'd like to not just start changing parts. Is there a way to check the function of the coil? I've heard they can go bad when they get hot or the engine is under load, so is that the next place to look?
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