Low Voltage to ignition coil

[timothylee]

I have a 1985 SeaSwirl runabout, 3.8 V-6, I'm only getting 8 volts to the ignition coil, what would cause this condition?

 

[timothylee]

I ran a hotwire from the battery to the + on the coil and I was able to start the motor but without it no fire.

 

[Redrig]

It's probably a ballast resistor either in the coil itself or one bolted to the intake manifold

Does the coil wire go straight to the solenoid ?

 

[Scott Danforth]

There is a ballast resister required with points. As points only need 8-9 volts when running. There should also be a wire that comes from the starter I terminal that privides 12 volts during cranking.

If you run 12 volts constantly to points they will burn out

 

[bruceb58]

If you measure with your points open, you should see full battery voltage even with the ballast resistor in there. Have you tried that?

 

[timothylee]

We found the problem, it was inside the starter solenoid, the retainer nut on one of the contacts had loosened and it was preventing the disc from making contact with both terminals thus not sending the full voltage to the coil while cranking, the motor starts great but now I'm having another problem, it also seems to be in the ignition system but we can't figure it out. The problem is intermittent, sometimes it will run great and then it will start running like crap, missing very bad, won't idle and if I can get it go while running at a good speed I can hear and feel a miss that sounds kind of like microwaving popcorn and occasionally it will let go with a startling backfire that sounds like a rifle shot. I have replaced the coil, points and condenser, cap and rotor, plug wires and plugs. The timing is set at 10deg BTDC at 600 rpm idle, the point gap is set at .018, voltage on the coil + while running is 9 volts, what could be causing this problem?

Thank you all for your help.

 

[gm280]

timothylee, I think what you are seeing on your voltmeter is a phenomena of PWM type syndrome. Let me explain. When you read a static DC voltage, you basically get the full reading. But when the engine is running, you are now reading a chopped DC voltage reading and it can still be full DC voltage buy being chopped so fast your voltmeter sees 9 volts instead. If is a type of PWM (pulse width modulation) condition. It is a condition of turning on and off a switch so fast that the reading looks like 9 volts even though you are switching 12 volts. JMHO

Most points are set a 0.020" for most OB point setups. Unless you know for certain otherwise, I would set your to 0.020" as well. JMHO

 

[bruceb58]

Set the dwell with a dwell meter and then set the timing.