Proper Way to Use Spark Tester

[rgballard]

I purchased a spark tester from Autozone, to test my motors. I have yet to see a spark jump the gap? I hook the one end in the plug wire boot and ground the other end to the frame. Then I pull start the motor. I have tried this on my 15hp (which does run) and I still don't get a spark?

Am I using this device wrong?

 

[CatfishMN]

Re: Proper Way to Use Spark Tester

Hi. Couple questions:

Did you buy the spark tester because you suspected no spark? if so, you may have taken a step in diagnosing the problem.

How far do you have the gap set? Bring it very close and try it.

When you say you are attaching it to the frame, can you be more specific as to where?

Others will jump in as well.

 

[wilde1j]

Re: Proper Way to Use Spark Tester

If you attached the ground end to the lower housing, it's likely plastic and you wouldn't get anything. You need to be connected to a good metal ground.

 

[Joe Reeves]

Re: Proper Way to Use Spark Tester

Depending on the ignition system (you didn't state what engine you have)..... set the gap to:

For a magneto or automotive ignition system: 1/4" gap.

For a solid state ignition system dating from 1968 to 1972 (dist cap under flywheel): 1/4" gap.

For a solid state ignition system dating from 1973 to present: 7/16" gap.

Test should be made with the spark plugs removed. The spark should be a strong blue lightning like flame.... a real SNAP!

Tester should be set up with one end of the tester connected to a spark plug lead, and the other end of the tester connected (grounded out) to the powerhead itself.

 

[rgballard]

Re: Proper Way to Use Spark Tester

I have a '56 30hp Johnson. I attached the grounded end to the one of the cylinder head screws (also wiggled it making sure it was getting a good connection). I have tried setting the gap from 1/4" to almost no gap and still don't get a spark. I did purchase the spark tester as a way to diagnose problems with the motor not starting. After using a multi-meter I diagnosed the components in the magneto (points, coils, wires) and replaced all the bad components and now I am wanting to test for spark, but I don't get any results. I suspect that I am not using the tester properly (having never used one), so that is why I ask.

I think that maybe I just am not getting the grounded end of the tester properly seated. Also I have found it difficult to watch the tester and try to pull start this beast. Any suggestions for that? I think the wife might have to come and help (if I can talk her into it, pray for me).

 

[Joe Reeves]

Re: Proper Way to Use Spark Tester

Get a buddy to help you.... he can crank the engine while you watch the spark. Perhaps you do not have the magneto components set just right.... see the following and do the tests for continuity:

(Magneto Capacitance Discharge Coils - Continuity Test))
(J. Reeves)

Check the continuity of the ignition coils. Remove the primary orange wire from whatever it's connected to. It may be connected to a powerpack screw type terminal, a rubber plug connector, or it may simply plug onto a small boss terminal of the coil itself.

Connect the black lead of a ohm meter to the spark plug boot terminal, then with the red ohm meter lead, touch the ground of the coil or the powerhead itself if the coil is still installed.

Then touch (still with the red lead) the orange wire if it's attached to the coil, or if it's not attached, touch the primary stud of the coil. You should get a reading on both touches (contacts). If not, check the spring terminal inside the rubber boots of the spark plug wire. Poor or no continuity of a coil is one reason for s/plug fouling.

(Magneto & Driver Coil Alignment)
(J. Reeves)

To align the coils properly, have the metal vertical portion of the coil yokes aligned with the inside edge of the bevel that exists on the top portion of the aluminum seat upon which the coils sit. This creates the proper distance between the coils and the flywheel magnets. Faulty alignment creats friction and the yokes of the coils heat up, turn blue and expand.

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

 

[rgballard]

Re: Proper Way to Use Spark Tester

Thanks for the info Joe, I have tested the individual components, but was looking for a way to test them all hooked up so I knew that I installed them properly.

 

[Wishiniwuzfishin]

Re: Proper Way to Use Spark Tester

If you're connecting the ground to a painted bolthead youi may have to file some paint off for a good connection. If you have a continuity tester or an ohmmeter you can use them just to find a good grounding spot.

Also the darker environment you work in for the test.....the better. Night is an ideal time to do it. It can be hard to see a good spark in bright sunlight.

 

[bob johnson]

Re: Proper Way to Use Spark Tester

darkness helps.....but id try this take one plug out, and leave one in...attach the clip for ground to the metal tip of the spark plug.....cant go wrong with that ground.. and plug the other end into the plug wire and pull it over....

and maybe believe you dont have any spark period,

then start going down the diagnostic chain.....make sure you have the kill switch hooked up...if it has one


bob