Can Power Pack damage Rectifier ? 96' 40hp Merc. 4cyl

[al r.]

Help... I brought my boat to this guy because it was hard to restart after stopping, it would not idle correctly and had to raise throttle arm up to get to start. First i was told and shown burned rectifier. Now I am told power pack is bad and engine is running on only 3 cyl. I told him it was running fine when i brought it in except for the afore mentioned problem. Is it possible I would not notice the 4th cyl not firing and can this be the problem with my restarting ? Also can the power pack short out the rectifier ?

[sschefer]

Help... I brought my boat to this guy because it was hard to restart after stopping, it would not idle correctly and had to raise throttle arm up to get to start. First i was told and shown burned rectifier. Now I am told power pack is bad and engine is running on only 3 cyl. I told him it was running fine when i brought it in except for the afore mentioned problem. Is it possible I would not notice the 4th cyl not firing and can this be the problem with my restarting ? Also can the power pack short out the rectifier ?

Shorting the rectifier could damage it which in turn would affect the performance of the power pack. The power pack gets its voltage from the recitifer so a shorted power pack could also short the recitifer. However, if either unit is shorted it is unlikely that the engine would run at all.

The voltage at the coil primary winding comes from the power pack so if it is running on only three cylinders then the rectifier is supplying voltage to the power pack but the output from the power pack to the primary winding on one of the coils (for example # 3 coil) or the coil itself could be bad. The clue in this example will be the lack of spark on #3.

I have an idea what it might be but won't guess without proper test results. If you can get him to test the entire ignition system begining with the stator then the problem will be obvious.

[Laddies]

The switch box (powerpack) does not recieve power from the rectifier, check your facts before giving bad info. The most common problem damaging rectifiers in a poor connection in the system.

[sschefer]

The switch box (powerpack) does not recieve power from the rectifier, check your facts before giving bad info. .

You are right, my bad. I'll never post on here again. I am hereby banishing myself from Iboats for life. Goodbye.

[verado7]

exactly the rectifier has no bearing on wether the engine runs or not it's just there to convert ac to dc for running lights and overchargeing batteries .


as far as the switchbox goes - maybe you have more than one issue going on - i would have hime check the stator too anyway - the rectifier and switchbox gets ac voltage from the stator and if it's the problem then you will fry another rectifier and and switchbox - i always encourage people to change them both out due to the expense of the switchbox itself .

["G"]

Many of you are on track and know your stuff. Knowing how the system works is the basis for repair. Here's what I recall from a year or so ago when I worked on one of these... The stator is like a "magneto" in these newer motors and when it acts up you start chasing wires. Yes, the rectifier is attached to the stator coils but that has to do with charge systems and the tach only. In fact the motor will run fine without the rectifier hooked up. The electronic ignition system works something like this; the flywheel magnet turns around the stator which is energized by 12 volts. It sends current to the trigger which sends the electrical charge to the switch box which sends that charge to the CDI for increased voltage then to the coil for a greater charge for the spark plug. Of course timing and flywheel magnet position are all in this mix. The rectifier is not in that mix except to keep the battery charged. The stator gets it's voltage from the battery NOT the rectifier. As for your #4 cylinder not firing, check the coil for that cylinder. They do short out or arc to ground leaving a visible carbon trail if you are trained to see it.

[al r.]

Thanks to all of you for taking the time to help me. I really appreciate it.