No Spark on B&S 6.75HP Motor

[forest813]

Just a short history with what happened and what I've done. When mowing I hit a large stone hidden in the grass which ended up breaking one of the mounting bolts on the bottom motor sump. The blade hub was ceased on the shaft so it needed to be heated to remove. A new sump replaced the broken one and when all was assembled to do a test run, the mower would not start. I changed the coil and spark plug and bepassed the kill switch but still no spark. I don't know what else to check. Is it possible that the fly wheel may be faulty which helps with the spark?

 

[DaveTN]

Yes, that's the first thing I would check. You can remove the top cover and
look down at the flywheel and see if it's partially sheared. It should get spark
even if the key is sheared, it just won't run. The key just keeps the timing correct.
The coil generates the spark from the magnets going past. You can also unplug
the kill wire from the coil and then check for spark.

 

[forest813]

The kill wire was unplugged with still no spark.

 

[DaveTN]

I don't see how the compression could be affected, but what kind of PSI are you getting?
Just curious. Do you have another coil to test it with? Weird things happen at the same time
occasionally. The coil could have just gone out.

 

[forest813]

The coil is new.

 

[bertsmobile1]

A few sayings you should think about
1) If it works then fix it till it dosn't
2) if it ain't broke don't try to fix it
3) only fix 1 problem at a time
4) the last thing you replaced will be the reason why it does not work now

So why did you decide to replace a coil that was obviously working in the first place
Put the old one back in the same position that it was in before you removed it
Most likely when replacing the sump you got the crankshaft & cam shaft out of time

 

[forest813]

Bertsmobile, are you a back yard mechanic or a journeyman? Should the engine be out of time, which it isn't, it would still produce a spark

 

[Rivets]

Forest, are you really asking your last question? You obviously have not been around this forum much and if you have you would now be ashamed for asking if Bert was a backyard mechanic. He’s got more know in his finger nail than a backyard mechanic like you. You owe him a big apology.
Second, if you were more mechanical and less DIY you would realize that after hitting that stone would have sheared the flywheel key. You said you broke a mounting bolt, so why replace the crankcase cover, unless that was also damaged and you didn’t tell us. When someone says check this or that, your response is like “I don’t know why you would say that, read my post”. My suggestion to you after you apologize to Bert is that you start over, first open the engine and check timing, then go through a normal troubleshooting procedure on testing an ignition system. Finally, I’m not a journeyman so you can also question my ability to post this and start hating me now.

 

[VegetiveSteam]

The coil is new.

New parts have been known to be defective. If you believe the spark plug and coil are good, the flywheel is the only component left in producing spark.

 

[bertsmobile1]

Bertsmobile, are you a back yard mechanic or a journeyman? Should the engine be out of time, which it isn't, it would still produce a spark

For decades I have always maintained that people should take what s posted in forums at face value rathe than hero worship because some one says they know what they are posting about so the fact that I run a repair business should not matter sa I can be just as wrong as the next man

The only information we have to work on is what you post
From your original post

When mowing I hit a large stone hidden in the grass which ended up breaking one of the mounting bolts on the bottom motor sump

So a reasonable assumption would be that the magneto was working quite fine before you hit the rock
So the burning question is why did you decide to replace it ?
As I said, "If it ain't broke don't fix it "

You said the sump was broken so you replaced it which is fine but that should have made no difference to the magneto which does not need to be touched to change a sump, a job I have done a dozen or so times .
IT requires a gasket or two to set the crank end float + an oil seal if you do jobs properly and depending upon the sudden stop damage may even need a new cam or governor as they can be broken in a dead stop.

Now the only thing that comes to mind is you bought one of those $ 10 "service kits" of evilpay, scamazon or feces book which contained a magneto coil retrieved from the scrap metal merchant because it was defective

I am still mystified why you replaced the coil
The timing key in the flywheel will usually break but that just takes 3 minutes to dress the key slot with a warding file and a new $ 2.00 key

Now because I work for myself I do not have to work for nasty aggressive or insulting people and this is the reason why I keep on turning down very lucreative offers from the local mower shops and why I am now popping over to your profile & enabling the "ignore " function
So you can enjoy throwing a tantrum ( which will do nothing to get your mower running ) while I enjoy not trying to work through your problems .