Ignitor question

[crvc]

I had to pull the engine in my '67 to replace seals on the oil cooler and the flywheel. The first thing I did was disconnect the battery. When everything was done and the engine was back in I turned the key and the #8 16 amp fuse popped. After a frustrating couple of days and 16 popped fuses I'm wondering if the problem could be with either the coil or Ignitor module. I damaged one early this year and it simply quit sending power to the spark plugs. This time it pops the moment I turn the key.

Any ideas?

TIA, kevin

[Piledriver]

Assuming that's using the original ignition feed black wire, make sure you don't have a bad backup lamp/socket/switch issue.

Easy to troubleshoot... unplug things then replug with a test lamp across fuse terminals rather than fuse.
Much cheaper too.

That wire tends to get krispy, which is why I only recommend controlling a relay with it to provide switched power off the starter or alt directly.

[Marc]

In factory configuration there is NO fuse protection to the Term 15 power to the coil (also the choke & idle cutoff solenoid, if equipped, or to the "hot" side of the inline fuseholder between Term 15 on the coil and the backup light switch on the transmission.
I suppose it's a good thing in this instance that someone has Mickey-Moused the wiring in your car so that a fuse blows in the event of a short on Term 15 to the coil. Better IMO to keep the stock layout and add an inline fuseholder up front to protect the main harness from sizzling if something's connected wrong in the engine compartment.
Disconnect all primary wiring from your coil other than the feed wire from the main harness to Term 15.
Connect each other wire in turn, switching the key "on" after each connection. The connection that pops the fuse is where your problem lies....

[crvc]

In factory configuration there is NO fuse protection to the Term 15 power to the coil (also the choke & idle cutoff solenoid, if equipped, or to the "hot" side of the inline fuseholder between Term 15 on the coil and the backup light switch on the transmission.
I suppose it's a good thing in this instance that someone has Mickey-Moused the wiring in your car so that a fuse blows in the event of a short on Term 15 to the coil. Better IMO to keep the stock layout and add an inline fuseholder up front to protect the main harness from sizzling if something's connected wrong in the engine compartment.
Disconnect all primary wiring from your coil other than the feed wire from the main harness to Term 15.
Connect each other wire in turn, switching the key "on" after each connection. The connection that pops the fuse is where your problem lies....

I put in a new complete wiring harness three years ago after a body-off restoration. With no electronic knowledge I followed the instructions exactly. The wiring to the fuse block doesn't match up with the '67 schematic I have but it has worked fine up til now. So the 15 side of the coil connects to several wires: The black wire from the harness, a wire to the back up lights, two wires to the carb and the red petronix wire. If I disconnect everything except the black wire and it still pops the fuse does that mean there's a short inside the harness?

Following Rob&Dave I checked the Petronix coil and an older one. Both had about 3 Ohms across the two terminals. And both had a little under 10,000 Ohms on the VOM between the center and either terminal if I'm reading it right. So that suggests the problem isn't in the coil? I have a third coil in the car now. The car will turn over but so far hasn't fired. But at least I quit burning the 16 amp fuse. My method of testing is to hold a screwdriver that's jammed into a spark plug wire while my wife turns the key. I didn't get a shock. Has my third Petronix module died? If so why would that short the fuse?

TIA,

kevin

[Piledriver]

If you pop off the black 15 terminal wire to the coil and it still pops, it's a harness problem.
Everything else )red to pertronix, backup lights) should branch off from the 3 prong there, so that should only leave the black wire in the circuit to the fuse.

Assuming that fixes it, add one circuit at a time until it pops ot the test lamp glows bright.

What size fuse are you using?

[crvc]

It's an eight fuse block. I wired it the way my '66 schematic showed. So the black wire is coming from the #1 fuse and is 16 amps. #2 to #7 are 8 amps and the last one is 16 amps.

kevin

[Piledriver]

The power wire only feeds 4 circuits if all are used:
Coil,
pertronix red power wire
backup lights
fuel solenoids and choke heater on carb.

Disconnect all of them and reconnect one at a time.

[crvc]

I found the short. I added the black wire to the coil and the fuse didn't pop. Then I added the conjoined wires coming from the carb. I got a blue flame as the connector was within a half inch of the coil. Hmmmm. Then for the first time I looked at the other side of the carb. When I was removing the engine the exposed connector had gotten bent and was touching the carb body. I bent it back and tried again to connect the wires to the coil. No blue sparks, no popped fuse. Success! Luckily I'd left the red petronix wire for last. Reconnecting them with my fingers crossed I was able to start the car. So the problem was never in the coil. It was also not in the starter switch or headlight switch or dome light wires or rear harness. If I had looked, I would have saved myself a lot of grief and about $30 in popped 16 gauge fuses.


http://i77.photobucket.com/albums/j47/k ... G_4025.jpg

[Dale M.]

When ever you have a situation where fuse continuously blows (after 3 rd one) put a test lamp across fuse position, it will light because of current (amperage) draw... When you find condition that makes lamp go out, you have found condition that causes fuse to blow...

Dale