Hi Folks!

Gotta weird thing going on with this old 318 where #3 plug is not firing. Replaced plug with new, wire with new (and swapped with another working wire from same engine) and cap and rotor for good measure. Still no spark for #3. What the heck else could it be???

S.

 

S -

What kind of ignition, points or electronic?
If you put a timing light on the #3 wire, does it strobe?
IOWs, how do you know it's not firing? Sorry, have to ask.

IF, everything you said is true, the on the only explanation is a lack of plug ground, which is nearly impossible or a short upstream of the plug. My guess is you're missing something more obvious.

Yeah, that's a weird one.

Archer

 

have you checked the compression on #3

 

Yes on timing light...#3 is dark, but it would need a complete circuit to light, correct? Ignition is points with original distributor BTW. Tried a new plug as well. Puzzling.

 

How would compression impact spark firing or not?

 

S -

You're going to have to break it down component by component.

Pull the plug and wire and set up an artificial ground (wire around the threads of the plug to a ground ) and look for spark.

Replace the plug with a ground wire to a chassis/block ground and check again with a strobe.

If there's no strobe on the wire, with the pick up at the dist cap, make sure the rotor is actually contacting the #3 terminal in the cap. Replace the points and condenser.

While unlikely, borrow another distributor and try it.

If all else fails, upgrade to an electronic ignition, they are pretty cheap and work really well.

Oh, was the 318 always this way, or this just start happening?
What else was done around the same time it started.

Again, think ground short. Start the engine at night and look for arcing.

Sorry, this is one of those "you have to figure it out" things.

Archer

 

Thanks all. Put in a new Proform MoPar EI kit which brought it back from a V7 to a V8 in minutes ;-)

 

 

Well to be clear, there wasn't an ECU. Remember, this was an original points/condenser setup that we now have replaced with an electronic setup. Who knows when was the last time the points were serviced...probably over 20 years / 40,000 miles ago... New cap/rotor/wires with only get you so far! :-)