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12hp Briggs & Stratton won’t start

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Discussion starter · #21 ·
Brad said:
Are you sure there is fuel getting thru the carb? Getting thru the jets?
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It's possible that it's not. It was running just fine the last time it ran, I engaged the PTO, it stalled, and never started again. It won't even fire with starting fluid sprayed directly into the cylinder. It took me until just now to even consider it could be a bad spark plug.
 
Discussion starter · #25 ·
So tonight I put a new spark plug in and verified I have spark, there was a burnt spot in the coil wire that I covered with heat shrink. Still no go it doesn't even sound like it's trying to fire, is there such a thing as a weak spark?
 
#26 ·
Weak spark would be yellowish in color at the plug gap. I would think even with weak spark and a new plug it would give a little indication of trying to start with a little fuel or quick puff of ether sprayed into the cylinder. With the information given and everything that was checked I think timing would be the only thing preventing at least an indication of life.

At this point I'm curious if whatever was attached to the PTO moves freely? Do you remember if the motor suddenly stopped when the PTO was engaged or did it bog down to the point it stopped? If it was sudden were there any squeals from the belts or did everything spin a little then come to a stop? Did you pull the flywheel off to check the key?
 
Discussion starter · #27 ·
nojgib said:
Weak spark would be yellowish in color at the plug gap. I would think even with weak spark and a new plug it would give a little indication of trying to start with a little fuel or quick puff of ether sprayed into the cylinder. With the information given and everything that was checked I think timing would be the only thing preventing at least an indication of life.

At this point I'm curious if whatever was attached to the PTO moves freely? Do you remember if the motor suddenly stopped when the PTO was engaged or did it bog down to the point it stopped? If it was sudden were there any squeals from the belts or did everything spin a little then come to a stop? Did you pull the flywheel off to check the key?
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The drive shaft going to the deck moves freely as do the blades. When the PTO was engaged it bogged down and stalled like sometimes happens if you engage a PTO at low RPM’s. It wasn’t a sudden stop. I have checked the flywheel key and it was intact with no damage. The coil bracket is good and tight so I don’t think it moved and changed the timing, but it certainly seems like a timing issue.
 
#29 ·
I assume it has a kill terminal on the magneto coil. Did you try it with it disconnected?
Then try it without carb, just spray a little starting fluid in intake. It should do something, even if it backfires (timing off).

Sent from my SM-S205DL using Tapatalk
 
Discussion starter · #30 ·
fuddyduddy1952 said:
I assume it has a kill terminal on the magneto coil. Did you try it with it disconnected?
Then try it without carb, just spray a little starting fluid in intake. It should do something, even if it backfires (timing off).

Sent from my SM-S205DL using Tapatalk
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When I bought this thing the wiring was an absolute mess. The only thing I currently have hooked up is the starter/generator in order to start it. I removed the rest of the wiring before this issue cropped up.
 
#33 ·
I have reread the entire thread several times and cannot provide any other solution other than swapping parts to find the issue. As dave_r and 38racing have stated not enough spark under compression I believe would point to condenser which is like $10. Magneto should be fine since it seems to be picking up the orientation of the flywheel. If that doesn't do the trick I think a cheap carb is like $40 which considering all the time and effort doesn't seem to bad at this point to rule that out even if you don't expect to continue using it. No matter the outcome please let us know how you make out or if you decide to swap it out for something else.
 
Discussion starter · #34 ·
I’m going to pick up a new condenser today. I ordered one through work yesterday, my cost was like $7. I’ll give that a try first, if that doesn’t do it I’ll pull the carb off and see what I get with starting fluid. If that works I’ll move on to the carb itself.
 
Discussion starter · #37 ·
ickma said:
I believe the proper spark plug is J19LM. I've been using an E3 FF-10 to get mine working.

When you turn it over do you hear a lot of noise from the front shroud? I had a problem with mine grinding
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I have an E3 plug in there now that cross referenced from the J19LM. I haven’t had the front shroud on since this issue started. But it was not rubbing at that time.
 
Discussion starter · #38 ·
Well it's been over a year but I got the tractor back from my buddy that was storing it for me. I cleaned and adjusted the points and put new connectors on the wire from the magneto to the points and the wire on the condenser and it fired right up.

I'm pretty sure the issue was the wire connector on the magneto wire.
 
Discussion starter · #39 ·
And it's down again. I put it on a trailer and hauled it 30 miles home and now no spark no matter what I do. In the process of troubleshooting the only wires I have on this thing are the wire from the coil to the points and the condenser wire. The coil is new, the points are a year old and the condenser is a year old. Neither have more than an hour or two of run time on them. This is driving me insane since it was running great yesterday.
 
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Kyle M.
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