Post by mckjake on Oct 14, 2010 21:17:52 GMT -5
Hi.
After many hours of tracking through my electrical system, and a couple of additional hours of reviewing past posts, I decided to throw my problem out here and see if the impressive collective wisdom has any suggestions. I apologize if I'm overlooking something simple that has been explained elsewhere.
The rig: "Mr T" is my '75 650B, with a completely stock setup. So, we're talking the standard points ignition system.
The problem: Up until a couple of months ago, Mr T had been running fine. A little sluggish under load, and a bit of a rough idle with some misfire, but otherwise fully able to rattle along from point A to point B with no problems. Until the day when I was cruising along the highway and it went from a smooth roar, to a steady sputter, to a complete dud. He wouldn't fire with the kicker, and the electric start wouldn't even click. So I towed him home to figure out the problem.
Since then, I've tracked through most of the electrical system and haven't found a good reason for Mr T's lack of life. Here's what I know:
1. The battery is in good condition and charge. It's sitting pretty at 12.6V, and I've been trickle-charging it at 0.5A every so often to make sure that's not the problem.
2. The headlight, brake light, turn signals, and gauges all have power.
3. The electric starter does not even click when the start button is depressed. Prior to the highway episode, it worked fine. I'm guessing that the solenoid got fried when I was overzealous in trying to get Mr T running while on the side of the road.
4. The coils have power going to them via the red/white wire. Voltage measured from the red/white to the negative battery terminal is 12.3V.
5. The primary coil resistance measures 4.2 Ohms, the secondary coil resistance measures 8.1 kOhms. Both of which are within spec.
6. I don't get a spark at either the spark plug (when pulled and grounded to the block, and kicking the engine over with the ignition and kill switch on), or the points (when opening the points by manually turning over via the alternator bolt with the ignition and kill switch on). I have even jumped a wire directly from the battery to the coils, in case I was missing something when measuring the voltage... but still no spark on the plug or at the points.
7. I replaced the condenser pack. Still no spark.
8. I replaced the spark plugs. Still no spark.
At this point, I'm stumped. I thought that I was isolating the coils, points, plug wires, and plugs by jumping directly from the battery to the coil. I've checked all of the connections, and they are good. And the resistance of the coils seems correct. So I should be able to get a spark, right? Could the coils still be fried even if the resistance is measuring correctly? I checked that the points have a solid ground when they're closed, but is there something else that could be preventing them from sparking?
Any suggestions are greatly appreciated. Thanks!
-Jake
After many hours of tracking through my electrical system, and a couple of additional hours of reviewing past posts, I decided to throw my problem out here and see if the impressive collective wisdom has any suggestions. I apologize if I'm overlooking something simple that has been explained elsewhere.
The rig: "Mr T" is my '75 650B, with a completely stock setup. So, we're talking the standard points ignition system.
The problem: Up until a couple of months ago, Mr T had been running fine. A little sluggish under load, and a bit of a rough idle with some misfire, but otherwise fully able to rattle along from point A to point B with no problems. Until the day when I was cruising along the highway and it went from a smooth roar, to a steady sputter, to a complete dud. He wouldn't fire with the kicker, and the electric start wouldn't even click. So I towed him home to figure out the problem.
Since then, I've tracked through most of the electrical system and haven't found a good reason for Mr T's lack of life. Here's what I know:
1. The battery is in good condition and charge. It's sitting pretty at 12.6V, and I've been trickle-charging it at 0.5A every so often to make sure that's not the problem.
2. The headlight, brake light, turn signals, and gauges all have power.
3. The electric starter does not even click when the start button is depressed. Prior to the highway episode, it worked fine. I'm guessing that the solenoid got fried when I was overzealous in trying to get Mr T running while on the side of the road.
4. The coils have power going to them via the red/white wire. Voltage measured from the red/white to the negative battery terminal is 12.3V.
5. The primary coil resistance measures 4.2 Ohms, the secondary coil resistance measures 8.1 kOhms. Both of which are within spec.
6. I don't get a spark at either the spark plug (when pulled and grounded to the block, and kicking the engine over with the ignition and kill switch on), or the points (when opening the points by manually turning over via the alternator bolt with the ignition and kill switch on). I have even jumped a wire directly from the battery to the coils, in case I was missing something when measuring the voltage... but still no spark on the plug or at the points.
7. I replaced the condenser pack. Still no spark.
8. I replaced the spark plugs. Still no spark.
At this point, I'm stumped. I thought that I was isolating the coils, points, plug wires, and plugs by jumping directly from the battery to the coil. I've checked all of the connections, and they are good. And the resistance of the coils seems correct. So I should be able to get a spark, right? Could the coils still be fried even if the resistance is measuring correctly? I checked that the points have a solid ground when they're closed, but is there something else that could be preventing them from sparking?
Any suggestions are greatly appreciated. Thanks!
-Jake
