zts 7500 running on one cylinder

[bsblhater]

hi everyone. when i put my zero turn up last week it was running perfect as it has since i bought it new 5 years ago. it appears to be running on one cylinder. i have checked the plugs both are dry and have spark and appear in good condition. i did a compression test on both cylinders i have 125 lbs on each. checked air filter and cleaned it. unplugged hose from fuel pump to carb it is pumping gas. it will sit and run on one cylinder fine but sounds very strange. the cylinder facing the rear of mower is the one not working. i determined this by letting it run several minutes and feeling the plug and cylinder. it is cold. i fear i may have a plugged exhaust and it does not look easy to remove to see if iam right. any ideas would be appreciated. oil level is near add mark and was changed at the beginning of the season. my next move is to buy 2 new plugs even though i pulled both of them and they look good and had spark.
thanks
jim.

 

[pugaltitude]

How did you check spark?
The only affective way is to use a spark tester.
A spark tester loads the coil to full and tests it as if under compression conditions.

If still sparking then its might not be drawing fuel into the cylinder to allow it to spark and fire.