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bekrause · Jun 22, 2008, 05:46 AM

After running for about an hour, the engine begins to cut out intermittently when mowing and/or driving up a slight incline, almost as though it were running out of gas. Sometimes it dies - I'll bring up the deck and put in park, and it starts right up almost every time. If it sets for an hour or so and cools off, I can mow for about 15 to 30 minutes before it gets hot again and repeats the process. Ignition problem?

ksr · Jun 22, 2008, 06:21 AM

Is it only when mowing on an incline that it does this? Does it actually die or do you shut it down when it starts to run rough?

It's possible the ignition module is going. Do you have the tool to check for spark?

bekrause · Jun 22, 2008, 01:31 PM

Originally Posted by ksr

Is it only when mowing on an incline that it does this? Does it actually die or do you shut it down when it starts to run rough?

It's possible the ignition module is going. Do you have the tool to check for spark?

Hi KSR,
Thanks for the reply.
It begins to do this while mowing on an incline after it has run for about an hour, and is hot. It does die if I don't stop moving, or at least mowing. It seems as though the more stress put on the hot engine, the more it acts up. It runs fine for the first hour or so. I don't have the tool to check for spark, at least I don't think I do... what is it called? And what are you actually checking, the amps or the volts, or both? If I had a manual for the motor this would be easier, but they usually don't come with the mowers.

ksr · Jun 22, 2008, 05:31 PM

Ok. I was an engineering tech for Tecumseh for about 7 yrs. then moved on to Briggs. An ignition module is electrical parts solidified in a "plastic" module. A spark "checker" is a spark plug of sorts that you hook the ignition coil up to, like it would set on to the plug. Then you ground it, to a head bolt or other non painted part of the engine and you can see how strong or weak your spark is. (Keep your fingers free while doing this or you may get the jolt of your life!! ) (This is a two person operation, as you need someone to crank it over, and someone to see how strong of an arc you get.) This will help you determine if it is an ignition issue or a fuel (vapor lock) issue. Yes, it may be a bit putzy, but it will help you determine the exact problem vs. throwing parts at the issue. One thing you could do is put the spark checker on at start up so that you can see how strong of an arc you get at start up, before it gets hot, and then check it again when the issue rears it's ugly head. This will let you know if it is an igntion issue or a fuel realted problem.

ksr · Jun 22, 2008, 05:37 PM

You could also use your spark plug, just un-screw it from the head and use something insulated to ground it to, and have someone else turn the engine over. Do it when the engine is cold and when it is hot to see if there is a difference in the strength of the arc. Make sure!! Whatever you use to hold the end of the plug to the head bolt is insulated, or else you will get a jolt!! If the color/intensity of the arc looks the same hot vs. cold, it's not an igniton issue, but possibly a fuel issue. If I had to guess, I'd place money on vapor lock.

bekrause · Jun 23, 2008, 07:04 AM

Originally Posted by ksr

You could also use your spark plug, just un-screw it from the head and use something insulated to ground it to, and have someone else turn the engine over. Do it when the engine is cold and when it is hot to see if there is a difference in the strength of the arc. Make sure!!! whatever you use to hold the end of the plug to the head bolt is insulated, or else you will get a jolt!!! If the color/intensity of the arc looks the same hot vs. cold, it's not an igniton issue, but possibly a fuel issue. If I had to guess, I'd place money on vapor lock.

Thanks KSR,

One note, I considered the vapor lock possibility and loosened the cap almost off, but still had the same problem. By the way, I'm assuming that a spark checker can be found at most auto parts stores, or do you prefer something else somewhere else?

ksr · Jun 23, 2008, 12:56 PM

You should be able to pick one up or just take the sp. Plg. Out and put the boot on it, let it rest against the head, so it grounds out, and have someone crank it over. The spark checker looks like a sp. Plg, but it has an aligator clip on it so it can hold it self in place.

bekrause · Jun 24, 2008, 06:36 AM

Originally Posted by ksr

You should be able to pick one up or just take the sp. plg. out and put the boot on it, let it rest against the head, so it grounds out, and have someone crank it over. The spark checker looks like a sp. plg, but it has an aligator clip on it so it can hold it self in place.

Thanks Again KSR,

I wanted to mention that I noticed that the gas line (neoprene hose) is very close to the motor block from the gas filter to the carb. It has always been there, and it is possible that this problem may have been there from day one, (May 2000), but I had not normally run the engine long enough to get it that hot. I'll try to get it away from the block and see if that helps. Otherwise I'll have to try to adjust the carb after getting the manual. I will check the spark first though. I was told by a lawn mower repair person locally that this particular motor had some issues with the overhead valve adjustments... sounded unusual, but thought you might know.

Timothy.159 · Jul 13, 2011, 01:01 PM

Hi, I had the same problem with a 16 hp tecumseh engin in my lawn mower. A friend of mine told me that he had problems with thee valve seats on old briggs and stratton engins lifting when the machine got hot. He told me to try taking the head off and removeing the vavles and if the engine has Valve seats, take a ball peen hammer and hit in the center of the valve seats until it is level with the top of the engine block. I tried it roughly a month ago and haven't had any problems with it since.