spark test where to ground?

[81white911]

If i pull the spark plug cable and leave the original plug in the block, and use a test plug with a ground wire wrapped around the threads. Can i ground it anywhere or is there some special place. Ive tried the intake header, the bracket on the engine fan cowling. I occasionally get a nice bright spark, but not consistantly as i crank the engine.

[sballard]

It shouldn't matter as long as it is conductive metal and grounded. I would think that the header is fine. For this test I image you are looking for any sign of spark.

For those of you who have never done this, DON"T TAKE THE ORIGINAL PLUG OUT. Find a spare plug to test. I remember watching in horror as an ignorant mechanic set my girlfriend's boat on fire by taking the original plug out, hooking it up to the wire and grounding it next to the open hole. When she cranked the engine, the flame that shot out of the combustion chamber was impressive! It even set the mechanic on fire - what a lesson!

[81white911]

just not getting a spark every rotation, Does anyone know if coils have intermittant failure ? or due they just die.

[jtfreels]

An alternative test, do you have a timing light? If so just hook it up as you would to test timing have someone turn the engine over.

When the timing light never went off I kinda new I wasn't getting any spark.


Jay

[RWebb]

Originally Posted by sballard

It shouldn't matter as long as it is conductive metal and grounded. I would think that the header is fine. For this test I image you are looking for any sign of spark.

For those of you who have never done this, DON"T TAKE THE ORIGINAL PLUG OUT. Find a spare plug to test. I remember watching in horror as an ignorant mechanic set my girlfriend's boat on fire by taking the original plug out, hooking it up to the wire and grounding it next to the open hole. When she cranked the engine, the flame that shot out of the combustion chamber was impressive! It even set the mechanic on fire - what a lesson!

hey - I know that guy. Sparky.

[ischmitz]

Originally Posted by 81white911

just not getting a spark every rotation, Does anyone know if coils have intermittant failure ? or due they just die.

you should see spark every other rotation..... remember it's a four-stroke with a 720 degree cycle

[81white911]

i was told to take the cable off the center of the distributor and hold it near the engine to see if i get spark and isolate any distributor problems. maybe i should put a spark plug on the end and ground it. Something about holding it sounds sparky to me.

[81white911]

intermitant spark off the coil cable, the CDI is shipping for analysis repair or replacement.

[rnln]

wow... scary. I have seen people do it this way all the time and I did it several times too.

Originally Posted by sballard

It shouldn't matter as long as it is conductive metal and grounded. I would think that the header is fine. For this test I image you are looking for any sign of spark.

For those of you who have never done this, DON"T TAKE THE ORIGINAL PLUG OUT. Find a spare plug to test. I remember watching in horror as an ignorant mechanic set my girlfriend's boat on fire by taking the original plug out, hooking it up to the wire and grounding it next to the open hole. When she cranked the engine, the flame that shot out of the combustion chamber was impressive! It even set the mechanic on fire - what a lesson!

[BK911]

Originally Posted by jtfreels

An alternative test, do you have a timing light? If so just hook it up as you would to test timing have someone turn the engine over.

When the timing light never went off I kinda new I wasn't getting any spark.


Jay

+1

IMO the best way. No need to disconnect anything, only takes a couple of seconds, and is relatively safe.