Lawn Tractor B&S 19.5hp died mid mow... wont start.

[jimkerr12]

Hi all,

I have a Craftsman 42" lawn tractor (not sure of model, cheaper one) with a Briggs and Stratton 19.5hp / 500CC motor. Been using mower regularly for 3-4 years. Yesterday, started with no problems and set out to mow, got about 15 minutes in when it started running a little rough, and loud. I slowed it down a bit to see if it would correct itself, but it only got worse. Stopped the blades and let her idle for a few minutes. It sounded like it was mis-firing... like a continuous series of small backfires until it finally chocked out, almost like it ran out of gas. Immediately tried to start her back up and she wouldnt turn over, starter engages and tried to turn, just didn't have enough power. Now I know my battery is weak, but I am almost certain this is not my problem..

I replaced fuel filter / spark plug / cleaned carb, everything seems fine... If i remove the spark plug she will crank, and I confirmed spark. If i put the plug back in I cant get it to turn over. If I try to turn the (not sure of name) round part on top with the screen I can, but it is very hard to turn. I have tried to jump start with my truck and get same results..

I am lost here and have no clue what is wrong. ANY help or ideas are appreciated!!

Thanks!!

 

[Rivets]

Pull the dipstick and see if the crankcase is overfilled. If it is, small the oil, to see if it smalls like gas. This will rule out a few things and give us a better place to start.

 

[jimkerr12]

Oil level is perfect, may have a slight gas smell to the oil, or at least an almost sweet smell, not quite like oil should smell...

 

[Rivets]

That rules out carb problems for now. The next thing I would be checking is valve clearances. Do you feel confident in doing something like that.

 

[jimkerr12]

That is probably outside of my abilities... I can tell you that It just attempted to start, It fired a couple of times and the entire thing shook violently...

 

[Rivets]

Time to stop and re-evaluate which direction to go. I recommend a repair shop.

 

[Brad66]

Make sure you haven't lost some or all of the motor mount bolts. This wont cure your non-start issue but when you say it jumps violently that makes me suspect that your engine isn't secured.

Be warned that when you jump your lawnmower with your truck there is a high probability that you will burn the starter out. The cranking amperage on your truck battery is way too high for those little mower starters.

 

[jimkerr12]

Thank you both for your replies..

Motor mounts present and accounted for. Now, as clueless as I am, it seems that (to me atleast) something must be locking up the exhaust side of things, If it sputtered out and died, and I cant turn it over unless the spark plug has been removed then maybe pressure not escaping properly through exhaust. Could this be what rivets was suggesting when he mentioned valve clearance??

Also, i forgot to mention previously.. The spark plug I replaced was BLACK.. lots of carbon buildup....

Thanks again for all your replies!

 

[jimkerr12]

OK.... Update...

Pulled the valve cover and noticed (excuse if my terminology is incorrect) the rocker arm was not connected to the push rod or the intake valve, it was hanging in limbo... Pulled the rod out of the hole and it was shape like a banana. I am guessing that is not the way it should look. I am going to replace the rod over the weekend, but if anyone may know what could have happened, please enlighten me!!

 

[reynoldston]

Be warned that when you jump your lawnmower with your truck there is a high probability that you will burn the starter out. The cranking amperage on your truck battery is way too high for those little mower starters.

Cranking amps has nothing to do with burning out the starter. 12 volts is 12 volts no matter how big the battery is.