Checking Amount of Spark?

[Fishinpedia]

Ive been trying to get my Johnson 150hp started for more than a week now. I have good gas going in. Thanks to ChampioNman I now know that the gas is moving through the carbs with no issues (gas flows from the drain plugs easily) I have checked my spark and I see spark when i ground a plug to the head. However someone else asked me if my spark would "jump a 7/16 gap" This I have no idea about. I dont even know how I would check for that.

Can someone tell me how I can check to make sure that I have a good strong spark and not a weak one?


My motor is a 2000 Johnson J150PLSSC

[Covurt]

I believe you are looking for an inline spark tester. I have one that has like a clear glas jar that you can see the spark. I've seen others that are open.

[ChampioNman]

It's called a spark board You connect it to all 6 wires and ground it to the block nd crank the engine checking to see it you can jump a 7/16" gap.

[SEAHORSE]

One quick check you can do to make sure you have enough spark for starting is to break off the ground strap on a known good sparkplug. Now the spark has to jump from the center electrode to the side of the plug which makes about 1/4" gap. If the ignition system can jump that 1/4", then it is strong enough to spark the plugs while under compression. Test for spark with all 6 plugs installed in the motor as that will give the same cranking rpm as when starting normally. You should ground the remaining plugwires to avoid overloading the coils with an open circuit while testing.

[Fishinpedia]

One quick check you can do to make sure you have enough spark for starting is to break off the ground strap on a known good sparkplug. Now the spark has to jump from the center electrode to the side of the plug which makes about 1/4" gap. If the ignition system can jump that 1/4", then it is strong enough to spark the plugs while under compression. Test for spark with all 6 plugs installed in the motor as that will give the same cranking rpm as when starting normally. You should ground the remaining plugwires to avoid overloading the coils with an open circuit while testing.

Seahorse can you give me more detail on how to do what you are telling me? I know next to nothing about outboards but am tryiung to learn

[omcforever]

"One quick check you can do to make sure you have enough spark for starting is to break off the ground strap on a known good sparkplug. Now the spark has to jump from the center electrode to the side of the plug which makes about 1/4" gap. If the ignition system can jump that 1/4", then it is strong enough to spark the plugs while under compression. Test for spark with all 6 plugs installed in the motor as that will give the same cranking rpm as when starting normally. You should ground the remaining plugwires to avoid overloading the coils with an open circuit while testing."

The term ground strap for people that dont know a lot about motors means the tiny piece of metal on the end of the plug from the side of it thats covers the center electrode that is bent to set gap...break it off. You just need one.

[fly by night]

Great information here! I learned something new in that post from Seahorse. Championman, where do I find one of those testers you just showed a pic of above? Thanks for the good information guys!

[ChampioNman]

https://www.google.com/search?q=outb...w=1366&bih=634

[316jughead]

The term ground strap for people that dont know a lot about motors means the tiny piece of metal on the end of the plug from the side of it thats covers the center electrode that is bent to set gap...break it off. You just need one. [/COLOR][/QUOTE]

Otherwise known as the outer ground electrode.

[fly by night]

Thanks Champ!