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jerrycmorrow

Active Member
Have a john deere js30 mower. Purchased a craftsman/briggs&stratton 190cc. 8.5 ft-lbs engine (2017) from BrandNewEngines and after it sitting around in weatherproof storage for about 6 months i installed it this spring.
Used it 3 times on a large yard with good amount of rocks and it ran perfectly. The last time using it the blade kissed a buried rock and mower died. Havent been able to get it started since.
This is what ive done so far:
1 - checked spark with in line tester. No spark. Checked tester on known good mower - great spark.
2. - pulled flywheel to check if the flywheel had slipped on the crank. The flywheel is perfectly aligned with the keyway. The key is straight with no indication of torque damage
3. - checked valves for opening/closing. No seen issues. Didnt check valves against TDC; probly should
4. - pulled magneto to check resistance
Primary windings are 1.8 ohms (0.4 - 1.5 spec’d)
Secondary is 10k (2.5k - 15k spec’d)
5.- kill wire shows 0 ohms
6. - plug wire resistance from plug connector to magneto is 0 ohms
7. - reinstalled magneto after cleaning it and where mounts on engine - no spark
8. - tested and replaced spark plug with new plug
9. - tested compression - 95 psi ( note this is a new off the shelf engine so is probly not broken in)
10.- checked spark - no spark

Only other thing i can imagine is the crank twisted inside the crank case. Gonna check valve timing against TDC

anyone got anything? Thanks for any help. Jerry
 
Jerry, if there is no spark, focus on that for now.

0 ohms means a short to ground. a flashing 0 usually means open. Get to know your meter by seeing what it reads with the probes touching each other. Check the kill wire again. Pull the plug and check the gap. if the crank was damaged and the connecting rod broke, it could have gone to the top of the stroke and smacked the plug. It also takes compression to run an engine, if you hae a compression tester check. if you don't have one put your thumb over the plug hole and pull the cord. See if it pushes your thumb off the hole. You can also use the pull cord with the plug in it to see if you can feel compression. All that said, parts that are moving at 3000 RPM don't like to stop suddenly. Most commonly I would expect anything of mass to want to continue in the path it was on.
 
jerrycmorrow said:
Have a john deere js30 mower. Purchased a craftsman/briggs&stratton 190cc. 8.5 ft-lbs engine (2017) from BrandNewEngines and after it sitting around in weatherproof storage for about 6 months i installed it this spring.
Used it 3 times on a large yard with good amount of rocks and it ran perfectly. The last time using it the blade kissed a buried rock and mower died. Havent been able to get it started since.
This is what ive done so far:
1 - checked spark with in line tester. No spark. Checked tester on known good mower - great spark.
2. - pulled flywheel to check if the flywheel had slipped on the crank. The flywheel is perfectly aligned with the keyway. The key is straight with no indication of torque damage
3. - checked valves for opening/closing. No seen issues. Didnt check valves against TDC; probly should
4. - pulled magneto to check resistance
Primary windings are 1.8 ohms (0.4 - 1.5 spec’d)
Secondary is 10k (2.5k - 15k spec’d)
5.- kill wire shows 0 ohms
6. - plug wire resistance from plug connector to magneto is 0 ohms
7. - reinstalled magneto after cleaning it and where mounts on engine - no spark
8. - tested and replaced spark plug with new plug
9. - tested compression - 95 psi ( note this is a new off the shelf engine so is probly not broken in)
10.- checked spark - no spark

Only other thing i can imagine is the crank twisted inside the crank case. Gonna check valve timing against TDC

anyone got anything? Thanks for any help. Jerry
Click to expand...
Have you looked at the contact point where the kill wire makes contact when you release the handles? Is it still making contact when you have the handle pulled back? Have you pulled the kill wire off the coil? Worth a try. I assume that you checked the gap when you looked at the woodruff key. I have learned from experience that sometimes you can’t detect that the flywheel has moved just by inspecting the key without removing the flywheel. But, a misplaced flywheel should still make a spark, it would just be mistimed. I don’t know why the coil would have been affected by suddenly stopping the engine but a no spark condition certainly is consistent with a bad coil. Bottom line: I suspect your spark is grounding out.
 
Oddjob said:
Have you looked at the contact point where the kill wire makes contact when you release the handles? Is it still making contact when you have the handle pulled back? Have you pulled the kill wire off the coil? Worth a try. I assume that you checked the gap when you looked at the woodruff key. I have learned from experience that sometimes you can’t detect that the flywheel has moved just by inspecting the key without removing the flywheel. But, a misplaced flywheel should still make a spark, it would just be mistimed. I don’t know why the coil would have been affected by suddenly stopping the engine but a no spark condition certainly is consistent with a bad coil. Bottom line: I suspect your spark is grounding out.
Click to expand...
After submitting my text i tried disconnecting the kill wire and had bright spark. Looks like it still makes contact when the handle is pulled back. Not had a chance to dig in to that system yet but it appears that the contact point is my prime target. Thanks much for your response
 
Oddjob, its fixed. You were correct concerning the spark grounding out.
The bracket through which the cable controlling the kill switch goes mounts on the “vertical” part of the handle. It is made out of plastic. Really a weak program. That bracket mounts to the handle with a plastic piece into a hole on the handle and also has a concave shape that supposed to keep the bracket aligned with the handle. That bracket pulled out enough to allow just enough slack in the cable to keep the contact point from clearing the ground.
Ive never seen this before.
Hope thats understandable. If not ask questions.
 
jerrycmorrow said:
I fixed the bracket with a hose clamp
Click to expand...
Good job! I love hose clamps. Have fixed many things with them, including a temporary fix for the water supply plastic pipe to my house, the loose steering column on a VW Cabriolet, and the oil drain hose on a John Deere RX75. When I lived in England and went to an auto parts store to buy some, I learned that they are jubilee clips and were invented in the 1920’s in England.
 
jerrycmorrow said:
Oddjob, its fixed. You were correct concerning the spark grounding out.
The bracket through which the cable controlling the kill switch goes mounts on the “vertical” part of the handle. It is made out of plastic. Really a weak program. That bracket mounts to the handle with a plastic piece into a hole on the handle and also has a concave shape that supposed to keep the bracket aligned with the handle. That bracket pulled out enough to allow just enough slack in the cable to keep the contact point from clearing the ground.
Ive never seen this before.
Hope thats understandable. If not ask questions.
Click to expand...
I suspected that the cable or kill mechanism had suffered when the engine came to a quick and violent stop. Glad you got it solved.
 
Oddjob said:
I suspected that the cable or kill mechanism had suffered when the engine came to a quick and violent stop. Glad you got it solved.
Click to expand...
Just to complete my earlier troubleshooting i did check valve timing against TDC. This was before getting to the kill switch. At least now i have fairly complete list of what is right on this mower
 
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