B&S has no spark....

[centerline]

B&S I/C platinum 19.5hp (2 cyl.) lost spark to the plugs..

engine model 42E707
type............2631 E1
code............9906025B

the engine has about 25hrs on it and is in like new condition except that it stopped running. this same thing happened about 2 weeks ago, but then it magically regained spark somehow, but it wont now..

after getting it running 2 weeks ago, we used it for about 30 minutes without any issues at all, it ran great. when we were finished it was put away as usual. when we tried to use it 3 days ago, it would not run or show any signs of trying to run, no backfire either, but it will only crank over....... fuel delivery is good, and the air filter is clean, but there is NO spark being generate

what I have done to bypass all any and all safety lockout switches is to disconnect ALL wiring from the engine except the battery wires to the starter.....
AND I have replace the coil/armature with new, thinking that it must have failed (replaced it twice actually, thinking that the new replacement was faulty) AND new spark plugs, but still cannot generate a spark.
I have even disconnected the ground/kill wire from the coil to insure there is no hidden grounding coming from it to the coil... still no spark.

I have worked on small engines most of my life and have never seen a problem like this, as most small engines will run by default if they are cranked over, and they NEED the coil to be grounded to stop running... I can see no reason there not to be spark to this engine, and have used up all my ideas as to where to look for the problem.

....if the flywheel sheared the key, it should still create a spark, but just be out of time....
....has the flywheel itself lost its ground to the engine somehow? the flywheel shouldnt have to be grounded itself because its only the magnet on the flywheel passing the coil that generates the spark from the coil...
....the coil base itself does have a good ground.
.....the presence of air and fuel make no difference at this time.

I have had a B&S tech tell me how to test the coil, but according to their way of testing, all the coils ive tried are bad/faulty, which makes me wonder if they told me wrong....
they said to check the ohms from the ground/kill terminal on the coil to one of the sparkplug leads and see if it shows 5 to 20 ohms... if not its faulty.

on my original coil, I get no reading from the kill terminal to the plug leads OR from plug lead to plug lead... on the first replacement coil I had, it was the same. on the new coil I CURRENTLY have, I get a reading from plug lead to plug lead, but NOT from the kill terminal to the plug leads....

can someone give me the correct procedure for testing a coil, and a suggestion or two as to where I may find the problem with this simple system... Thank you

 

[Rivets]

There are no tests which the DYI can preform on today’s coil, due to the Hall effects sensor embedded in the coil. In fact some coils can be damaged if even a small amount of current is allowed to pass through in the wrong direction. If I remember the ignition systems on these old L-head twins, there should be a kill wire running between the two coils. When you checked for spark did you remove the kill wire from both coils, on just disconnect the wire from the kill circuit going to the key switch? Also, try setting your air gap at .008”

 

[Scrubcadet10]

The opposed L heads only use 1 ignition coil with 2 plug wires and a. Single kill wire.

 

[bertsmobile1]

Modern coils all contain a chip that replaces the points so they are now called "Modules" and are 4 times the price they should be.
IT is called a Hall Effect Trigger
Because of his very few can be tested off mower without very expensive test gear.
As no parts of the module is repairable it s a moot point to the consumer.
It either works or won't work & requires replacement.
I tried to check using the numbers you have posted but they appear to be wrong.
IF it is an side valve opposed twin then t has a double ended coil and these are very sensitive to the plug & the plug gap
With a double ended coil each plug is a ground connection so usually both need to be grounded or you do not see any spark.
Also the sparks are very weak at cranking speeds ad you need some sort of tester rather than looking for flash at the plug.
I use the one with a red / orange tube because it is easier to see in daylight.
Modern plugs do not have glaze on the center electrode and modern fuel is conducive so it could also be a bad plug allowing the spak to run down the insulator & not jump the gap.

 

[Scrubcadet10]

I assume your engine is rotating fast enough? Just reading through my repair manual for the twin,says 'Magnetron ignition requires at least 350 RPM to produce spark.

 

[Its Me]

A quick and easy free way to test remove the engine shroud, remove the coil, sandpaper or file the two bosses that stick up to hold the mag on and then sand the bottom of the coil that mates to it, they must ground by surface contact, will not ground through the threads, with you cover off and remove the kill wire to rule out anything that could be bringing it to ground, test for stark, a few of the past ones that I have worked on that was the problem and especially the low cost push mowers, think it through, Joe