Paul_B Posted August 4, 2005 Posted August 4, 2005 My 16HP briggs motor that is out of a 3416H will sometimes run rough and sounds like it it's missing when it gets hot. Also, tonight it wouldn't restart after I shut it down. I had to wait about 30 minutes before it finally would start. Cooler days it seems fine. The cooling fins are clean too. The motor had new points and condenser last year. Any ideas what might be wrong? UPDATE: I replaced the points and condensor and the problem is gone. It ran perfect at higher RPMs and I mowed my back yard with no problems with it being in the mid 80's. Upon inspection of the old points and condensor, the connection between the screw terminal and the point's contacts was loose. I also checked my old condensor with a multimeter. It checked out to be open, but when I checked the night it quit, it was shorted.
dirtsaver Posted August 4, 2005 Posted August 4, 2005 Lean burn condition due to sucking air around intake or carb(throttle shaft or welch plug?) Leaking head gasket? Weak ignition coil breaking down when it heats up? Just a few ideas.
D-17_Dave Posted August 4, 2005 Posted August 4, 2005 Easyest thing to elliminate is still the points and condeser. A condenser is apt to get moister in it from just sitting out in hummid weather. This will heat up and short it out when hot. If this doesn't do it then check your valve clearance and change the coil. If your handy w/ wireing, you could rig a automtive coil off the points to help narrow the problem down. Then switch back to the internal coil when you have found the problem. Or changed to problem coil.
Paul_B Posted August 5, 2005 Author Posted August 5, 2005 I'm going to wire up an external coil and see if that helps. I don't think it's fuel related since it was getting gas when I tried to restart it.
MrSteele Posted August 5, 2005 Posted August 5, 2005 I'd lean toward either the condensor or a bad coil. Have a spare coil handy? Or, try the automotive coil and see what happens. You'll likely find that to be the problem. If not ignition, check the exhaust valve clearance.
BrianP Posted August 8, 2005 Posted August 8, 2005 Paul, My 10hp 3410 Simplicity has just developed the same problem. It began happening about 3 weeks ago. One thing's for sure, the problem isn't fuel related. After a brief period of cranking I have fuel dripping out of the bottom of the carb. Also, when I pull the spark plub wire and hold it away from the top of the plug there is no spark...at first. After a few seconds it starts sparking and tries to fire. Then when I put the plug wire back on and fire it up it runs like a champ for as long as I need it without missing a beat once. Last Saturday I dropped $25.00 on a new coil with built in resistor. Same problem. What's frustrating is that the only pattern I can find is related to the machine being hot. I let it sit for a couple of hours and it fires right up. I was going to work on the points, but maybe the condensor is to blame since the weather here in SC has been quite humid lately. Maybe some others here can weigh in with a more definate solution. Brian
johnmonkey Posted August 8, 2005 Posted August 8, 2005 I've seen many discussions and the problem was clogged or blocked fins under the shroud. That means pulling the engine. JH
jbird243 Posted August 9, 2005 Posted August 9, 2005 I have had several old engines do the same --- coil would stop working correctly after the coil heated up --- I think heat would increase the distance between cracked wires. A cold defective coil may test ok but fail when it heats up. Always do basic spark tests with and without the spark plug.
Paul_B Posted August 12, 2005 Author Posted August 12, 2005 I mowed with it last night and after mowing for 20 minutes, it just shut off and wouldn't restart. Also another observation is at lower RPM's it ran OK last night before it acted up. At higher RPM's it kinda missed. Saturday I'll have time to see what the culprit is.
Paul_B Posted August 14, 2005 Author Posted August 14, 2005 It was the points and condensor. See my original post for details.
Vinnie_A Posted August 15, 2005 Posted August 15, 2005 Can you buy points and condensor at an automotive store for a Simplicity 725, if so what do I ask for. Are these common with any auto points and condensor?
Paul_B Posted August 15, 2005 Author Posted August 15, 2005 quote:Originally posted by Vinnie_A Can you buy points and condensor at an automotive store for a Simplicity 725, if so what do I ask for. Are these common with any auto points and condensor? They are different than that of the automotive ones. Some parts stores sell ones for lawn mowers, but not all. You'll need your engine model number to figure out which set of points and condensor to buy. A good lawn & garden parts place should be able to get you what you need with no problem.
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