Briggs backfiring and stalling out

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  #1  
Old 01-03-06, 04:19 PM
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Thumbs up Briggs backfiring and stalling out

I have a 15 hp B&S on a John Deere Sabre riding mower. The engine starts and runs a couple of minutes then backfires a couple of times and stalls out. After it cools down it does excaltly the same thing. I have replaced the spark plug. Could the problem be what I think is called the iginition coil?
 
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  #2  
Old 01-03-06, 09:46 PM
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need a little more info, don't think its the coil right yet, side valve or over head valve? whats the year of the engine? if its old enough, could have points, but it does sound like the carb, black smoke when it does backfire?
 
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Old 01-03-06, 09:51 PM
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something in the carb maybe?
 
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Old 01-04-06, 03:10 AM
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Sticking float valve...?

Hello all, V8driver & Cheese. Sounds like a sticking float valve? I imagine the carb needs a good cleaning anyway. Like V8driver said more info will help. Can be a combo of issues. Your at the right place...these guy's are good! Ron
 
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Old 01-05-06, 12:59 AM
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It does sound like the coil is bad. There are no points on that engine to worry about. Try loosening the fuel cap in case the tank is developing a vacuum. If that doesn't do it, I'd think about putting a coil on it. If it smokes, or gas is dripping from it, then that's another story, and the carb may be at fault. Otherwise, I'd look at the coil.
 
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Old 01-05-06, 04:09 AM
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Two minutes is an odd amount of time for the symptoms to develop. At two minutes the engine is not yet at operating temperature...generally when the coil will begin to fail, or, immediately upon start-up, if indeed troublesome. Also, this time lapse is not typical of potential carburetor issues...this would show up immediately or when overly hot (intake manifold overheats and creates a vapor lock). At two minutes, the first thing that comes to mind is the fuel cap or fuel pump. Here's the steps I would take at my shop: 1- Have an inline spark tester (Briggs part# 19368) ready. 2- Run the engine until the moment it fails. 3- Immediately install the tester, plugging in the spark plug lead and grounding the tester to the engine and check for sufficient spark at the tester. NOTE: Having a second person would be helpful. If good spark at the tester, ignition is good. If not, post back and we'll address that. If good, loosen the fuel cap, (listening for a burst of air entering the tank) and try to restart the engine and run (with cap loose) for as much time as pinpoints or eliminates the cap as the suspect problem. If you still have trouble at this point then you will want to remove the fuel line at the carburetor fitting, have a catch can (coffee can works well) ready, crank the engine over and observe whether there is sufficient fuel flow from the fuel pump. Try these and post back with your findings as well as your engines' ID numbers.
 
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Old 01-05-06, 04:37 AM
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I better stick to 2 Cycles

The coil was the last place I would have looked but after I think about it...it kinda makes sence. I guess the Carbs with the anti-backfire device is what I was baseing my thoughts on but it also is an electrical issue not a carb issue?Keep educating us. The clueless, Ron

Originally Posted by cheese
It does sound like the coil is bad. There are no points on that engine to worry about. Try loosening the fuel cap in case the tank is developing a vacuum. If that doesn't do it, I'd think about putting a coil on it. If it smokes, or gas is dripping from it, then that's another story, and the carb may be at fault. Otherwise, I'd look at the coil.
 
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Old 01-05-06, 11:49 AM
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I thought about that solenoid too Ron. The reason I dismissed it is that the engine does start. Typically, if the solenoid is creating a problem, it won't start at all. Since the engine starts, the solenoid is opening, allowing fuel to pass.

The backfire when it dies points to either ignition or fuel restriction. If the engine starves for fuel it can backfire. The 2 minute run time is a bit short for blaming on a faulty coil, but I'd check that pretty quick. If not, the 2 minute time might be because the carb bowl is not filling fast enough, and the engine runs out of fuel. Once you let it sit awhile, the bowl fills back up and you can start it again...until it runs out, etc... That's where the fuel cap, fuel pump, and possibly a collapsed fuel line could be at fault.
 
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