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B&S 18.5 spark and fuel no start

#1

J

JPalmer

Hi! I'm new here, hope y'all can help. I was given a Troy-Bilt 42 inch Tuffy. 18.5hp B&S OHV single cylinder. Getting spark (grounded plug against engine,) and getting fuel (plug was wet from trying to start.) I've used it once since it was given to me. Took awhile to get running due to old gas, but have run all of that plus a half tank new gas. Stalled yesterday. Spins strong. Started to adjust valves and found that bottom (I think exhaust?) valve barely opens. Rocker arm hardly moves to compress spring. Went ahead with adjustment but still won't start. Any ideas or advice? Thanks!!


#2

I

Ifixdit

JPalmer said:
Hi! I'm new here, hope y'all can help. I was given a Troy-Bilt 42 inch Tuffy. 18.5hp B&S OHV single cylinder. Getting spark (grounded plug against engine,) and getting fuel (plug was wet from trying to start.) I've used it once since it was given to me. Took awhile to get running due to old gas, but have run all of that plus a half tank new gas. Stalled yesterday. Spins strong. Started to adjust valves and found that bottom (I think exhaust?) valve barely opens. Rocker arm hardly moves to compress spring. Went ahead with adjustment but still won't start. Any ideas or advice? Thanks!!
Click to expand...

If you have a valve that is not opening I suspect you have a bad lobe on the camshaft.


#3

J

JPalmer

I was suspecting that, but wasn't sure if it would just be all of the sudden like that. It was running fine then just stalled. Didn't choke down or anything, it was like I turned the key off. It's a beater of a mower, but cuts really nice and even.


#4

R

Rivets

I would check the valve clearance again. If you have set it right it should not change if adjustments were correctly done. Set both valves at .006" with the piston 1/4" past TDC on the compression stroke. Cam lobes do go bad, but you want to make sure that there is not something else wrong before opening up the engine. Have you checked for a sheared or partially sheared flywheel key? You will have spark, but at the wrong time.


#5

J

JPalmer

I went over the adjustments several times since I noticed the bottom valve not opening all the way, but I will go over my steps. Firing at the wrong time sounds like a good possibility, but still doesn't explain the valve issue. Oh and thanks for the help guys!


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