Spark plug wires only fire when partially unplugged

[67D100Pickup]

1967 318

I was adjusting timing for a new rebuilt engine and all of the sudden the timing light stopped blinking.

#2, 3 and 4 wire also dead.

#5,6,7 and 8 wires all work.

For 1 through 4 wires, if I pull the cable off the distributor or spark plug and hold it close it sparks again, and the timing light confirms it and the engine speed increases.

I have replaced the wires and coil.

Electronic ignition.

What is going on?

Jeff

[712edf]

SO the front 4 cylinders don't fire but the rear 4 do??

Routing issue maybe?


Bucky

[PwrWgnDrvr]

Weird *#%^ always happens with EI.

[67D100Pickup]

SO the front 4 cylinders don't fire but the rear 4 do??

Routing issue maybe?


Bucky

Correct. I can't figure out why they fire when I disconnect and hold them close to the distributor or spark plug. Works both ways.

[67D100Pickup]

Weird *#%^ always happens with EI.

Yeah. The front 4 wires are obviously a little longer than the rear.

The same ignition worked for the last 5 years, VERY low mileage, maybe a couple of hundred miles, max.

And it worked fine after the rebuild until yesterday.

Can't figure out why they only work when disconnected.

Jeff

[PwrWgnDrvr]

Did you pull and examine the plugs? If the gap was somehow closed, that would be a dead short and would cause this symptom.

[67D100Pickup]

Yes, that's where I'm at now. Plugs fouled.

It appears the choke was not connected and it has been running with full choke fouling everything.