Smoke coming from 351 PCM engine yesterday!

lakeaustinag · Jul 14, 2010

I have an '82 Ski Supreme with a rebuilt 351 PCM in it. I installed a new starter solenoid (part at the back of the engine) last weekend. We took it out for a run last night and it started right up so we drove it around for a bit. We stopped for a while to swim and left the battery on to listen to the radio. After about 20 minutes, the wife noticed some white smoke coming from the engine hatch. I opened it up and noticed the smoke was coming from the ignition coil and there was also some water spraying from where one of the wires entered the coil. I have no idea where this water was coming from. I shut off the batter and waited for a bit and the smoke and water quit but the boat wouldn't start after that. We had to be towed back into the dock. Does anyone have any idea what my problem could be? Extremely weird. Thanks.

Lyle29464 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Did you buy the solenoid at a marine store?

Icefire55 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

pretty evident problem no? you have a water leak that sprayed electronics.... find the leak, replace the coil ?

lakeaustinag · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

I bought the solenoid from a marine dealer. How much is a new coil?

Lyle29464 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

I have seen solenoids that had the posts labled for a car. Some inboards ground the solenoid like a car with the bolt that holds it on. Some will not ground this way and you must hook a ground wire to one of the small terminals. I have seen the ground wire hooked to the I terminal and it was correct. I am not saying that yours should be that way. I am just saying some times a rebuilt solenoid can be a problem hooking up. Check your wiring schematic. Your points might be fried also. I would really follow the wires to see if something got mixed up when you replaced the solenoid. Coils are not much but you need to get the correct one. some will get hot if you run them on 12 volts. Check to see if your engine requires a ballast resistor.

haulnazz15 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Coils usually run 30-40 bucks.

Skybreeze · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

I have had this same issue. I turned the boat off and then turned the key back on to lift the motor before putting on trailer. There was a funny sound coming from the engine and the rev counter went off scale. You probably didn't hear this if you had the radio on. The engine had stopped with the rotor lined perfectly with one of the distributor cap contacts and was continually arcing. This would probably burn out your coil. Also check your rotor and cap for signs of wear on one contact. This is a very rear situation and if it happens the next time you turn the key on would usually be to start the engine so wouldn't matter. But because you left the key on the coil was energized.

bruceb58 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Turning on your inition without the engine running and POINTS CLOSED is what did in your coil. Has nothing to do with the rotor lining up with anything as the last poster mentioned.

bruceb58 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Skybreeze said:
Also check your rotor and cap for signs of wear on one contact. This is a very rear situation and if it happens the next time you turn the key on would usually be to start the engine so wouldn't matter. But because you left the key on the coil was energized.

The only time you will get a spark out of the secondary of a coil is if the points are opening and closing which won't happen if the engine isn't turning. No arc means nothing is going to be wrong with the rotor and cap. Even if the coil was firing, what do you think happens while the engine is running?

Skybreeze · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

I don't have points. This is what happened to me and as soon as I flicked the key to misalign the rotor the problem was solved. This can happen and has happened to me. Yes I agree if you have points but unsure as to whether the person having this problem has points or not.

bruceb58 · Jul 14, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Had nothing to do with the rotor itself but the position sensor on the distributor shaft. What was happening to with yours was similar to that of the points being closed since it was causing too much current to go through the coil. If the coils was then trying to discharge and did not have a good path to ground, that will kill a coil in a heartbeat since it since the high voltage field in the secondary can blow through the insulation into the primary windings.

Skybreeze · Jul 15, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Please relise I'm not an expert so value your input. My understanding is that for current to flow there must be a path. For a path to occur the rotor must also align with a dizy contact. Am I right or am I missing somthing

bruceb58 · Jul 15, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Skybreeze said:
Please relise I'm not an expert so value your input. My understanding is that for current to flow there must be a path. For a path to occur the rotor must also align with a dizy contact. Am I right or am I missing somthing

The current flows through the coil way before the rotor aligns with the contact on the distributor cap. Previous to that moment there is current being flowed through the primary of the coil. This develops a huge magnetic field in the secondary. When that current flow stops(ie points open or in the case of your system, the position sensor turns off the electronic switch) and the field collapses causing the coil to want to release its energy somewhere. Even if the rotor wasn't pointing at the distributor contact, that energy will go somewhere.

Skybreeze · Jul 15, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Thanks for the clarification. Due to our discussion it can probably be assumed that he has not wired things incorrectly but marely leaving the key on has caused the problem. Maybe this is why he is going through so many coils and is also why things that are used when engine is off are usually wired on a separate switch panel so they don't require ignition on.

lakeaustinag · Jul 15, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Thanks for all the input guys. I'm not too knowledgable about electric stuff so I have two questions. First, what are "points" and also will simply changing oit the coil solve my problem? Will I be better off next time if I turn the key to the left to the accessory position to run the radio while we're swimming?

haulnazz15 · Jul 15, 2010

Re: Smoke coming from 351 PCM engine yesterday!

lakeaustinag said:
Thanks for all the input guys. I'm not too knowledgable about electric stuff so I have two questions. First, what are "points" and also will simply changing oit the coil solve my problem? Will I be better off next time if I turn the key to the left to the accessory position to run the radio while we're swimming?

Yes it would be better to turn the key to the ACC position, only, most boats I've been on don't have an ACC position. The points they are referring to are inside the distributor cap, there should be one point for each cylinder you have. As the rotor lines up with each point, it sends the current from the coil to that corresponding cylinder's spark plug.

bruceb58 · Jul 15, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Yes...don't turn the key to the on position without running the engine. That is why you are burning up your coil. If you have the original distributor in there you have points. Open up the distributor cap and take a look.

This is what points look like:

lakeaustinag · Jul 17, 2010

Re: Smoke coming from 351 PCM engine yesterday!

Well I just put a new coil on and still nothing happens when I turn the key. To make sure I wired it up right, I put the three red wires on the positive post of the coil. Is that right? What do I do from here?

Smoke coming from 351 PCM engine yesterday!

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