Pamco install, blowing ignition fuse

[minnesota mike]

Hey everyone. Got an issue to run by y'all.

I'm working my way up to the PMA swap on my '81 650 Special (got stranded last week because the alternator isn't charging adequately - finally biting the bullet). I just got done installing the Pamco ignition, got it wired, started it up (with the electric start), adjusted the timing, everything going just fine.

Then I went and put on the chrome covers, went to start it again, and... nothing. Starter won't turn over. Tried kickstarting... can't get it running. Battery is charged, everything is basically stock on the bike. I checked the connection from the positive terminal on the coil to the kill switch (red/white wire) and it is fine. Kill switch itself is still operational.

EDIT: Finally noticed the ignition fuse is blown. So what could be causing this? I've read over some similar forums but no clear conclusions were drawn, seems to me. I'll check the coil and Pamco tomorrow, per Pete's guidelines.

I appreciate any help.

 

[minnesota mike]

On a related note, is it better to kill the engine with the ignition switch or the kill switch, or doesn't it matter? The documentation for the Pamco ignition says not to leave the ignition on without the engine running, so I was just curious about this.

 

[Derek]

Double check that you don't have any exposed wires, pinched wires and that everything with the Pamco install is tucked nicely. Pull the advance unit and Pamco covers off, replace the fuse and see if it blows again without the covers. If it does, you have other problems, if not you know it's something there.

As far as turning the bike off, your choice but when Pete says "make sure the ignition is not left on with the bike not running" he means the entire/main electrical system (the key switch, not the handlebar kill switch). I always turn mine off with the key, but only because it's mounted front and center and I don't see a reason to flip two switches. Also, that way I know the bike is shut off, a good habit regardless.

~ Derek

 

[minnesota mike]

Thanks Derek. I tried another fuse and idled her for a few minutes, then upped the RPMs and the fuse blew again, covers off.

One thing I've noticed is that with the new ignition the spark seems much hotter than it used to be. If I can use an analogy, she used to start like an old lady getting out of bed in the morning, and now she starts like she woke up in the middle of the night and the house is on fire. I suspect that this could be part of the problem, but any suggestions on diagnosis and/or solutions?

 

[pamcopete]

minnesota mike,

I would check your battery voltage at high RPM. You may have a bad regulator. Also, if your starter wont work with this fuse blown, then you must have other things connected to the fuse? Like, what is connected to the fuse besides the PAMCO?

 

[minnesota mike]

Thanks pamcopete, I went to look at what you suggested, but the fuse is now blowing as soon as I turn the ignition to on. I suspected a short somewhere, so I started cleaning up connections. Then I tested the coil (which is new as of last August) per your steps found on another thread. Measurements are in bold:

1. Using the lowest scale on the meter, measure the resistance between the primary terminals with the wires removed. Should read from 2.5 to 4.5 Ohms. 2.1 Ohms
2. Using the highest scale on the meter, measure between one of the primary terminals and the center core of the coil. Should be infinite resistance. (open) OL
3. Measure between one of the primary terminals and one of the plug wire terminals. Should be infinite resistance. (open circuit) OL
4. Measure between one of the plug wire terminals and the core of the coil. Should be infinite resistance (open circuit) OL
5. Measure from one plug terminal to the other. Should be 15,000 to 20,000 Ohms 12,400 Ohms

So it appears the coil is bad. Could this be causing the issue? I don't want to confuse causation and correlation... could it be instead that a short or other electrical issue (which was causing the fuse to blow in the first place) also fried the coil? I'm hesitant to just throw in a new coil until I rule out other possibilities.

I still haven't investigated the wiring diagram to see what is all on this fuse, but I'll be checking those connections next.

Thanks again.

 

[pamcopete]

Minnesota,

Well, from those readings, I would not jump to the conclusion that the coil is bad. I would first find some way to verify that my meter is OK by either measuring a known good coil, or going to Radio Shack and buy a couple of 5 Ohm resistors and measuring their resistance in parallel for 2.5 Ohms.

The measurement on the high side of the coil may have been influenced by your fingers touching the probes, or the meter could be wrong here as well, so while you are at Radio Shack, get a couple of 10K or 15K resistors and measure those for reference.

Also, what is the part number of the coil in question here?

 

[minnesota mike]

Pete,

Very good point. The part number of the old coil is 17-6803. I have coil 17-6822 (brand new, came with the ignition kit) and that tested out within the ranges specified, which is why I assumed my meter was working ok. Still a good idea to verify.