Why am I blowing condensors

[Capt.P]

Re: Why am I blowing condensors

Thanks for the response everyone.Ihave a omc manual with wiring diagrams and the whole bit,according to it the resistance should be 2ohms.I measured the volts with the wire unhooked from the coil, engine off.

 

[bruceb58]

Re: Why am I blowing condensors

Hmmm...maybe it is 2 ohms since you have a 4 cylinder engine...probably doesn't use as much current as I thought it would.<br /><br />Since there is no current going throught the resistive wire, there will be no voltage drop across the resistance the way you are measuring it. You should read battery voltage which you do.<br /><br />Now hook that wire back up to the positive side of the coil, undo the negative wires, add your jumper from the negative side of the coil to ground and make another measurement. Make sure you use an 18 guage wire or bigger for this test.<br /><br />Just remember this...it's called ohms law:<br /><br />R*I=V<br /><br />R = Resistance<br />I = Current<br />V = Voltage<br /><br />The amount of current that flows through that wire will cause the voltage drop across that wire

 

[Capt.P]

Re: Why am I blowing condensors

bruceb58 Ijust ran down to the boat and did the test you suggested 2 wires off negative side of coil,jumper from neg side to ground measured volts on pos side 6.5 volts.then my volts are ok?

 

[bruceb58]

Re: Why am I blowing condensors

That sounds right to me. When you engine is running it will be close to 8.5V.<br /><br />Now that you have that figured out, you can concentrate on why the points are burning up.<br /><br />What diesel dave said actually makes a lot of sense to me. Maybe it is possible the voltage flyback blows the condensor and then the points once the condensor has failed.<br /><br />What condition are your spark plug wires?<br /><br />How do you set your dwell? Do you use a meter? If you have the dwell set to high, that can actually cause burnt points because they are closed too long. I never rely on gap...always use a meter.

 

[Capt.P]

Re: Why am I blowing condensors

Thanks bruce that had me baffled, I just couldn't figure out whty I had too much volts when my resistor wire tested ok, all along I was testing it wrong now to figure out why my condensers are blowing.My plug wires appear to be ok it doesn't miss or anything in damp weather.As far as setting the points I always set the gap I just can't get my hands on a dwell meter, could this be the reason.Also my shift interupt was not working but I found that the wires at the plug were loose now it works ok.I have heard of bad condensers I bought both that blew at the same marina wonder if they had a bad batch??

 

[bruceb58]

Re: Why am I blowing condensors

No problem. I am an electrical engineer so all that stuff with voltage drops and current is second nature to me.<br /><br />How did you determine that your condensors were bad?<br /><br />You can pick up dwell meters for around $35. Amazon has them.<br /><br />Normally, the burning of points is cause by the rapid callapsing of the field in the coil and then arcs across the points. The condensor slows down the collapse so that you don't get the arc.<br /><br />If your dwell is too high, it means your points are closed longer, which means current is flowing through your points longer than necessary.<br /><br />What diesel dave was saying is that you have this huge EMF formed in the coil's secondary windings. What if the wires weren't up to snuff and this EMF had no place to discharge. Could it possibly discharge through the primary windings and arc across the points!

 

[olbuddyjack]

Re: Why am I blowing condensors

Or intermitently discharge down the coil wire boot(carbon track) to the coil negative.

 

[Capt.P]

Re: Why am I blowing condensors

The first time I had a problem bruce it took me about 3 days to find the reason , I changed points, ran jumper wires ,cleaned carb, changed coil, set timing every thing I could think of ,I didn't expect the condenser cause it was just replaced.This time I had a spare and as soon as it started missing really bad and couldn't get more than about a thousand rpm out of her I changed it out on the river and whola runs like a kitten again.olbuddyjack what do you mean "discharge the coil wire"Thanks Guys!!

 

[Buttanic]

Re: Why am I blowing condensors

"I didn't expect the condenser cause it was just replaced."<br /><br />Was it a Mallory condenser that caused the problem.<br /><br />I had a new Mallory condenser go bad in a couple of hours. I think Mallory has a problem with bad condensers.

 

[Capt.P]

Re: Why am I blowing condensors

The marina seid it was a mallory condenser but it said OMC on the package.I had 2 of these go.