Riding mower intermittently dies

bdm1978

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I am a new member and would appreciate any help available. I have a 1992 Dynamark mower (model d4316) with a 16 hp b&s vanguard engine. It has ran perfectly until recently when it has begun to die intermittently. It will always immediately restart, and run smoothly from 5 seconds to 10 minutes before it dies again. Because it runs and dies so smooth I am assuming it is an electrical problem. Have good fuel to carb. When it dies, it's like you turned the key off with no sputtering, just shuts off. Have checked switch, solenoid and safety switches and all have checked o.k. Is it possible that it could still be one of these mentioned, possibly only breaking down intermittently, or do I need to look toward the engine at coil or something else? Once again, thanks for any help possible.
 

ILENGINE

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This one could be fun. It is possible is could be a fuel issue with something shutting off fuel flow temporary like a ping pong ball. Sounds more like either a intermittent short to ground shutting off the engine. Or a loose/corroded connection some place in the wiring harness.

Possibly an ignition module issue, but those don't normally start back up. They have to set a few minutes. But then again I have seen those things do weird things. Easiest way to check that is to install an inline spark tester, and then go mower you lawn. When the engine is dying check to see if it still has spark.
 

SeniorCitizen

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To eliminate about 99.99 percent of the electrical as the culprit, disconnect the mag ground wire at the engine and give that a try. To kill it, with the ignition switch in the off position, touch the mag wire back to its terminal.
 

bdm1978

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To eliminate about 99.99 percent of the electrical as the culprit, disconnect the mag ground wire at the engine and give that a try. To kill it, with the ignition switch in the off position, touch the mag wire back to its terminal.

Thanks ILENGINE and SeniorCitizen. I will try the electrical fixes first, as I have a hard time thinking it is a fuel issue concidering how clean the engine stops and will always restart immediately.
 

bertsmobile1

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Pull the cover and check the magneto wire carefully.
On a engine of that age good chance it has chaffed a small hole in the insulation, or it could have hardened & cracked.
 

bdm1978

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Thanks for all the input. Spent most of the morning testing safety switches, key switch, solenoid and checking wiring (which all tested o.k.), I decided to go ahead and change solenoid because of age. I also bought a new battery since I had been jump starting old battery. Had 12.79 v at starter with switch on and starter would not turn over. New battery is 280cc. Put my portable jump start to battery and motor started right up and ran for about 5 seconds. Unhooked kill wire at motor and tried it again and it ran perfectly. I will check more into that asap. My question is about the battery. Could I have gotten one that has good voltage but low amperage, or is this a problem that I have created by frequent jump starting and now my starter needs more amps to start?
 

ILENGINE

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Make sure the ground wire is clean where it connects to the frame, and tight.
 

SeniorCitizen

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Not familiar with your engine but if it has overhead valves and a built in compression relief i'd be checking the clearance on them. Normal cranking amp draw is closer to 150 amps than the 280 your battery is capable of.

Your new battery can be load tested . Usually a free test.
 

bdm1978

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Make sure the ground wire is clean where it connects to the frame, and tight.
Thanks ILENGINE for the reply. I actually did run a ground wire from neg battery post to engine block. Wouldn't even try to turn over.
 

bdm1978

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Not familiar with your engine but if it has overhead valves and a built in compression relief i'd be checking the clearance on them. Normal cranking amp draw is closer to 150 amps than the 280 your battery is capable of.

Your new battery can be load tested . Usually a free test.

SeniorCitizen, engine is a 16hp vanguard twin cylinder approx. 22 yrs old. Runs perfect when started. Ran gnd from battery to block with no change. Will have battery stress tested before going deeper in engine. Thanks
 
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