Ballast resistor? why

[thewallflowers]

I am tracking down why my old starfire wont start. i am only getting about 5 volts to the starter switch and gauges. It looks like someone prior to myself made an attempt to rewire the dash as all the wires are either red or orange. I can not find any info on the ballast resistor as it seems to be in the mix of wires. it is connected to the solenoid where the battery connects and is getting only 5 volts where i think the resistor is. it looks like a gob of glue around a blade then a wire comes out of it. The OMC book shows' it but has no info on it so how do i tell if it is bad? I can jump the new solenoid and turn over the motor and if i jump the coil i can start it. with the key on it will stay running after i take the jumper wire off until i shut off the ign switch. any ideas??

 

[mike_i]

I haven't heard of a ballast resistor but to measure the value of a resistor you need to remove at least one lead from the circuit but you need to know what the value should be. Does the manual state the value of the resistor? Do you have 12v between either side of the resistor and ground? Normally when a resistor goes bad it goes open, which means heat.

 

[Chris1956]

You might tell us the make and year of your engine, and repost in the correct forum for that engine.

Old points/coil ignitions had resistors to drop the voltage to the points to help keep them from burning.

 

[dwco5051]

The fact that it stays running after the ballast resistor is back in the circuit and the jumper is remove pretty much rules out a bad resistor. Check the voltage at the coil when it is running. It should be around 9 volts or so. Since the gauges are also not getting voltage I suspect you have a bad or corroded connection some where elsewhere or a faulty ignition switch.

 

[mike_i]

Isn't that what a condenser is for? They're just a capacitor that absorbed the rapid spike in voltage to keep the points from arcing. I'm going to read up about ballast resistors, I may as well learn something today.

You might tell us the make and year of your engine, and repost in the correct forum for that engine.

Old points/coil ignitions had resistors to drop the voltage to the points to help keep them from burning.

 

[sam am I]

So during starting/cranking on these/some older designs, when the starter's solenoid engages, simultaneously and automatically within the proper type solenoid, an internal connection is made that bypasses the ballast resistor, this "starting connection" sends straight 12V to the coil's + terminal.

After starting (solenoid dis-engaged), the ballast resistor is switched back in series with the coil's + terminal, this then reduces the voltage a few volts normally.

Switching the ballast resister out(bypassing it) assures the coil receives the highest possible voltage(hottest/best spark) that could possibly be sagging(10'ish volts for example) during cranking, switching the resistor back in then when the engine is running keeps it (the "external resistor" required coil) from over heating.

This is of course is only true of a coil that requires a ballast resistor, some use um , some don't, depends on what was installed and if the proper solenoid is also installed, usually they are marked.

With this said yes, you can jump the solenoid and/or bypassed the ballast resistor (just as the solenoid does)......It won't hurt anything.

 

[Chris1956]

Point arcing and point burning are two different things. A condenser absorbs the voltage as the points open to reduce arcing, and immediately feeds that voltage back into the ign coil, helping to generate spark. Condensers are used on magneto and battery/coil/points ignition systems.

Point burning only occurs on battery/coil ignitions. As Sam says, a lot of these ignition systems provide +12VDC to the ignition coils for starting, and then drop it back to +8VDC or so, to help stop point burning.

Transistorized ignitions which is an old term for CDI ignitions originally used points for ignition timing. They reduced the point voltage way down to mostly eliminate point burning. They also increased the voltage to the ign coil to 300VDC or so, to upgrade the spark from 20K volts to 500K volts or so.

 

[ahicks]

Isn't that what a condenser is for? They're just a capacitor that absorbed the rapid spike in voltage to keep the points from arcing. I'm going to read up about ballast resistors, I may as well learn something today.

No. A resistor drops voltage. A condenser stores it (much like a battery). This statement is spot on-
"Old points/coil ignitions had resistors to drop the voltage to the points to help keep them from burning."

 

[thewallflowers]

Lots of info! The boat is a 76 Starfire with an OMC outdrive, my guess is an 800, the motor is an OMC 190, Ford 302. There is a big voltage drop between the starter solenoid and at the ignition switch, 12 V vs 5V. If there was a bad fuse then I should get no voltage which is why I was "guessing" the ballast. I had it working last year when I took it to the lake. It gave me some issues that made me think it was a poor circulating problem. So I changed out the engine water pump and like an idiot I left the battery connected and while putting on the alternator the wrench hit the motor and caused a big spark. I changed the 150 amp circuit breaker but I can not find any other fuses. There is not enough voltage to even run the tilt from the switch. I can jump that and make it go up and down. the book shows the power coming from the battery to the solenoid then to the ammeter, I have a volt meter instead installed before I got it. Then splits off to the ignition switch and the ballast resistor. from the other side of the resistor it splits off to the + of the coil and back to the starter. All this shows 2 fuses somewhere. I know you should be getting 12 volts at the ignition but it's only 5 volts. Time to rewire?

 

[dwco5051]

Without being there and testing I am thinking that replacing the amp meter with a volt meter might be causing your problem. An ammeter is wired in series, a volt meter in parallel. Depending how it was wired when replaced it could very likely be the culprit.

 

[GA_Boater]

Lots of info! The boat is a 76 Starfire with an OMC outdrive, my guess is an 800, the motor is an OMC 190, Ford 302. There is a big voltage drop between the starter solenoid and at the ignition switch, 12 V vs 5V. If there was a bad fuse then I should get no voltage which is why I was "guessing" the ballast. I had it working last year when I took it to the lake. It gave me some issues that made me think it was a poor circulating problem. So I changed out the engine water pump and like an idiot I left the battery connected and while putting on the alternator the wrench hit the motor and caused a big spark. I changed the 150 amp circuit breaker but I can not find any other fuses. There is not enough voltage to even run the tilt from the switch. I can jump that and make it go up and down. the book shows the power coming from the battery to the solenoid then to the ammeter, I have a volt meter instead installed before I got it. Then splits off to the ignition switch and the ballast resistor. from the other side of the resistor it splits off to the + of the coil and back to the starter. All this shows 2 fuses somewhere. I know you should be getting 12 volts at the ignition but it's only 5 volts. Time to rewire?

Thread is moved to the OMC section. Do not start another thread.

 

[kenny nunez]

It appears from what you are describing you actually have a electric shift model not a 800.
The resistor you are describing on the starter is actually a fuse. The epoxy is a sealant. There also should be one on the alternator. You can get what is called a fuseable link from NAPA in various amp ratings. It is a short length of wire and you will have to use crimp terminals to splice it in.
Probably a 50 amp would be enough.

 

[thewallflowers]

Sounds like your right on. The other old boat I own has the 800 sticker on the outdrive and this one only says OMC. I will take my multi-meter and see of that fuse is still any good. I had the alternator rebuilt last year it's a 1 wire type now. It may have gone bad so I will pull it off and take it to the place I had it rebuilt to test it. I believe that the 150 amp circuit breaker that I just replaced is from the alternator. That was on it before and I went ahead and put on the same. I can't get to it till next week so I will update it then. Thanks