What does this test tell me? - UPDATE

[Scuda11]

Hi there. I have been reading that I can run my engine, and remove each spark plug one at a time to see how it reacts. <br /><br />What exactly is it telling me, and obviously I can't put the boot back on when the engine is running right? So should I do one at a time, then start it, starting at the TOP right cylinder?<br /><br />Thanks!<br />1983 200 hp Johnson.

 

[petrolhead]

Re: What does this test tell me? - UPDATE

Yes you can pull the boots off and push them back on while it's running, you won't get a shock through the rubber. If you pull one off and it makes no difference to the engines running, then it tells you that plug wasn't sparking in the first place, so then you know to look further and find out why.<br />If you pull a boot off and the engine slows and runs rough then you know that plug was OK.

 

[Scuda11]

Re: What does this test tell me? - UPDATE

Awesome, thanks PH!

 

[Dhadley]

Re: What does this test tell me? - UPDATE

You can remove each spark plug WIRE one at a time. That will tell you if its running on that cylinder or not. <br /><br />You should use a plastic set of pliers. Its a rather shocking experience otherwise.

 

[Scuda11]

Re: What does this test tell me? - UPDATE

Thanks Admiral. As I have said earlier, electricity in any form and I are not good friends, so I will heed your advice.<br /><br />Thanks!

 

[JB]

Re: What does this test tell me? - UPDATE

If the engine does not drop rpm when you pull the spark plug boot, IAL, it means that cylinder is not making power. Could be spark, could be fuel, could be compression.<br /><br />Good luck.

 

[Namcali]

Re: What does this test tell me? - UPDATE

I think it will shock you if handled by bare hands. It won't kill you though, however, I wouldn't recommended. The magnitude is about 25000V but the current is very low.<br /><br />The alternative method is to use the timming light. Common, there are some better ways to test it.<br /><br />Nam

 

[petrolhead]

Re: What does this test tell me? - UPDATE

It certainly won't hurt to use some form of isulative protection when you pull the boots off, but I never have in 30 or so years of messing about with engines, and have never been shocked.<br />Maybe I'm just less conductive than some guys?

 

[stairliftoheaven]

Re: What does this test tell me? - UPDATE

i would use rubber gloves and rubber boots but then i'm welsh....

 

[Scuda11]

Re: What does this test tell me? - UPDATE

I am going to wear ALL of those things mentioned. I hope I can see ok.<br /><br />I will send pics of my outfit. <br /><br />

 

[kennedyt]

Re: What does this test tell me? - UPDATE

There is another area that applies. If you want to conduct checks on the engine when you have it on the trailer and don't have a test wheel installed or a test tank available, you can simulate puting the engine under a load by pulling all the plugs except for 1 and check each cylinder one at a time with less potential of hurting engine as you rev up.

 

[Dhadley]

Re: What does this test tell me? - UPDATE

Hydra Sprt 25, if youre suggesting running the motor with a plug out ya gotta be careful. With the motor running and a plug out, gas will come out the spark plug hole. That coil is still going to produce a spark that has to go somewhere.<br /><br />Be careful!!

 

[Scuda11]

Re: What does this test tell me? - UPDATE

Think I will stick with one at a time, sorry Hydra, I am just not that safe. lol

 

[sledhead041]

Re: What does this test tell me? - UPDATE

What type of engine are you doing this on? One Ing systems can be harmed by doing a cyl. drop test like this. A better way of testing is to use a piece of vacuum line from a car (the high carbon type) and putting that on the plug terminal and then putting the boot on the hose. the engine will start and run like that and then you can use a test light that is grounded and touch the other end of the test light to the hose to take the voltage off of the sparkplug.

 

[self taut]

Re: What does this test tell me? - UPDATE

just thought i would add a bit of info here not really related to the test you plan to conduct but a useful piece of info non the less.working on choppers with the army i learned alot about electrical systems.one of the facts they taut us in ait is that as little as half an amp can kill you.how many amps does your plug wire have running through it?

 

[Scuda11]

Re: What does this test tell me? - UPDATE

I'm not sure, but would I just do better by starting up, pulling one plug, listen for change, shut off, replace plug, go to next, etc, etc?

 

[Scuda11]

Re: What does this test tell me? - UPDATE

^^

 

[blgrams]

Re: What does this test tell me? - UPDATE

Just a thought from someone who has been playing with electricity for a living for 25 years. It is usually not the electricity that permanantly hurts you at low power levels such as a spark plug or household voltage. what usually hurts you is what you do when you react to a shock like falling off a ladder or off a boat with a running motor <br /><br />Bruce

 

[kennedyt]

Re: What does this test tell me? - UPDATE

Didn't mean pull the plug.....meant pull the wire.

 

[merc_500]

Re: What does this test tell me? - UPDATE

he knows.<br /><br />good luck let us know how it goes!