Mower won't turn over

[excalibur2]

ahhh, ok. Not sure if it makes a difference but I removed the magneto completely off the machine and I bench tested it with a small ohm meter that takes a small cell battery, like a watch battery.

 

[bertsmobile1]

No you have not tested anything.
All you have done is shoved a probe in and got a number which has no meaning whatsoever.
There are two sets of windings in a coil and you gave one number further suggesting you don't have a feintest idea of what you are doing.
The circuits in the meter transform that 3 V into thousands of volts so the battery size is irrevelant.

 

[excalibur2]

"There are two sets of windings in a coil and you gave one number further suggesting you don't have a feintest idea of what you are doing."

Of course I don't know what I'm doing, this is why I posted the issue on this forum in the first place, but at least I'm giving it hell in the process!

Anyway, pulled connector to magneto off and cranked over, yes I am getting spark. With connector back on no spark. So the only safety switch I have not replaced is the reverse switch but I'm doubtful that has much to do with it.

 

[bertsmobile1]

I really am not trying to sound superior, but what works best is people ask you to do something and you do what you are asked to do then report back the results.
There are 2 benefits in doing things that way.
1) people who like to do things for themselves get a clear idea about how to go about the task
2) others who are following the thread who know what to do will chime in if the person rendering the help makes a mistake or misses something.
There is a funny sort of ettique where one person will take up a problem and the other techs just watch from the sidelines unless they feel something requires an itervention.
Everyone is more than happy to explain why you get asked to do something , however most who post don't really care why, they just want to go out and mow asap.

In this case you are now where you could have been a lot earlier had you have just tried it with the plug disconnected.

The reverse switch earths out the magneto when the PTO is on.
So next step is to turn the PTO on & off a few times . make sure it is off then try for a spark again.
Good news is the magneto is not fried. apparently they are not bad with a strong garlic sauce :laughing:

Now the kill circuit is a different animal.
The kill circuit works by connecting the wire you just removed to ground and to make things really complicated, there is a few of them all working in parallel but they do that in pairs
In the starting mode
Reverse + PTO ( not in all cases )
Brake + PTO
In mow mode
Brake + Seat
Reverse + PTO
Seat + PTO

So now grab they multimeter and check for continuity
Work backwards from the magneto wire.
test both side of each plug with the switch in both on & off positions.
Then pull the plug off the switch & test the wires in the plug again

Also remember that this is a ground circuit so it will be either open or ground but a short to the frame, pinched wire etc will not blow a fuse so you also have to test each wire, from plug terminal to plug terminal.
It is very common for this wire to strip where it passes through or under the heat shield around the cylinder which is doubly hard to find because every time you touch the wire, it changes.
Do all the testing with the wire off at the magneto end, remembering some of the switches with 4 wires on them can be live

 

[excalibur2]

Ok now here's a twist - I'll get spark with small black wire connected to armature only when seat safety switch plunger is in the UP position. Press plunger down { as if a rider were on the seat} and no spark. Seems this is working the opposite of the way it's supposed to. With seat switch disconnected from harness I get continuity with plunger down but no continuity with it up, which is the way it's supposed to work. Now if I plug it back into the harness it works the total opposite way.

Shown here is continuity with plunger not depressed, as if rider were OFF mower seat, as it should read on a properly working switch





And shown here is continuity with plunger pressed in, as it should. So when reinstalling the switch into the harness connector it's working the total opposite way. Strange.

 

[excalibur2]

Now I am getting spark with spark plug grounded to head with seat switch both in and out. Negative battery cable also heating up a bit. Has to be a ground issue somewhere

 

[bertsmobile1]

If the wires going into the ground terminal look grotty & corroded then there is a good CHANCE that there is significant corrosion inside the terminal.
You can try a jumper lead from the battery neg to a good grounding point. close to the starter.

As stated before the seat switch is not in circuit while the engine is cranking as you have now verified.

The worry is if the engine is cranking and the magneto is firing is the engine running ?
If not try a little fuel in the carb, starter spray is easiest to use, just don't overdo it.

 

[excalibur2]

I cut off the ring terminals on each end of the neg cable. One looked clean, the other end dirty and oxidized. Crimped on 2 new ring terminals, will put back together tonight. Will also clean area underneath solenoid mount for better ground. Now that I have spark, I have not tried to actually start the engine just yet - I'm first trying to determine why i'm getting spark { with spark plug out of head, grounded to block} with seat switch in either up or down position before i put everything back together. One minute the seat switch works the opposite way as it should be, next minute spark in both positions. Just one of those things where i gotta find out why, for my own sanity lol!

 

[excalibur2]

Ok I couldn't wait so I just reconnected the neg cable with the newly crimped ring terminals. Fired right up! Now, if I could just figure out why the seat switch will allow the rider to start the engine in either position. Being it will START now I should just leave it alone. One thing I did do first thing this morning is remove the internal spring grounding clip inside the harness connector where the seat switch plugs into. The 2 blades on the switch were hard going into the harness connector at times and it seemed these 2 internal spring loaded grounding prongs were interfering with a snug fit of the switch. My gut feeling says the manufacturer added this grounding clip to prevent everyone from bypassing the seat switch by simply unplugging it from the harness. When working properly, with this device in, if you disconnect the seat switch, the 2 clips spring back and short out the circuit and prevent starting. Being I had spark in either position before removing this clip, I'm thinking a new harness connector is in order.

 

[bertsmobile1]

BECAUSE THE SEAT SWITCH IS NOT PART OF THE STARTING CIRCUIT
So it will start with the seat switch in any position.
However if you let the parking brake off without being in the seat it will kill the engine.