No spark in #5 cylinder

[sneed99]

We've changed plugs, wires, cap, rotor and still don't get spark from #5 plug wire. Engine runs except for #5 cylinder. Clueless as what to check or where to go, any help or ideas would be appreciated. Possibly bad coil??? bad stator???? again any help, clues.....

 

[XJ Eric]

well try tracing it back from the spark plug. Your coil would be bad if you had NO spark whatsoever. You're not getting spark in #5. How'd you test that out? Hold the plug wire near the plug and see if it arcs? Thats that usual, just make sure you're using a pair of spark plug pliers. That arc can hurt. It sounds like the cap plug or wire. You are obviously getting spark to the rest of the plugs if its running.

are you positive the wires and cap are good? The rotor is probly good since you're still getting spark to the other plugs. Sounds to me like your problem is either the plug wire or cap, or all three.

I know you said you changed them, but you KNOW spark is getting out of the cap and rotor because the engine runs, right? So, it HAS to be either the #5 plug, wire or cap. DID you use brand new cap wire and plug when you changed em out? if not that may be your problem. Does sound frustrating though, good luck...

 

[sneed99]

yeah brand new everything, very puzzling, we had a blown head gasket and had the head worked on, installed everything back to spec and don't seem to get any spark out of #5, we pulled the plug out of cylinder #5 and didn't see any spark as we turned motor over and while engine was running with original equipment that is why we went and just got everything new and still have same problem?????? We're thinking this might be what caused the blown head gasket....no ignition in #5????

 

[XJ Eric]

did you pull the plug and look at the electrode while cranking it over?(ground it against the block and insulate yourself from the plug of course, while doing this) If it runs you're getting power to the other plugs, so there can't be anything wrong with the rotor and cap. Try scraping up the inside of the cap for the #5 wire. maybe there's some grease or wax that is preventing good transfer of electricity. You know power is getting to the cap and rotor you just have to figure out why its not going from the rotor through the cap and down the wire to #5. Maybe the plug can't ground to the block? Have you cleaned the threads out on the block? have to be careful not to get any crap in the cylinder but maybe its on the grounding end of the plug. Try switching plug and wire from #5, with say Cylinder #2 for example, and see if you get spark. If you get the wire and plug from #5 to make spark at number 2 then you know its not the plug and wire. It would be somehwhere in the head. Maybe its too gunked up for a good ground between plug and head.:dunno:

You'll have to figure out how to clean it without letting the gunk in the cylinder.

 

[scca28]

Try switching plug and wire from #5, with say Cylinder #2 for example, and see if you get spark.

That line got me to thinking, are you sure ONLY #5 is not firing? Reason I ask is number 2 plug shares the same CPS timing spot on the flywheel. If there is any damage to the flywheel on that position it's possible your #2 is not firing properly as well. The other two positions are for plugs 1+6 and 3+4.

 

[lawsoncl]

Have you tried a new spark plug? They can break up inside and not spark.

 

[Matthew Currie]

The first thing I'd do is get or make a test plug. Just take a little hose clamp, and attach a piece of wire with an alligator clip to the threaded portion of a good plug. Now attach the plug to the plug wire and the clip to ground, and run the engine. This allows you to do it without holding on, and making sure that the plug is grounded well.

You can buy one with the clip spot-welded to the plug body.