B&S 625EX fouling plugs, guzzling fuel.

[cprodave]

This engine on my TroyBilt TB200 mower is suddenly fouling plugs and doubling fuel consumption. Was previously mowing whole lawn in 1/2 tank fuel. Now it uses more than 1 tank to complete the job. RPM'S cycle up and down more now vs. before. Oil level remains fine, possibly slight overfill but has been this level for more than 1 year h
I will check Compression and also Spark (using adjustable gap tester). What should values for each of these be? Also as I disassemble and do visual inspection for "smoking gun" what should I look for? Stuck or partially stuck Intake Valve, etc?
Thanks in advance. Brand new plug after only 1 hour runtime is very black.

 

[ILENGINE]

What does the air filter look like and have you replaced it recently.

 

[slomo]

Sticking carb needle and seat comes to mind.

NEVER over fill the oil. Keep it exactly at the full mark only. Check oil prior to every mow. There is a reason they put the full mark where it is.

Most car engines the crankshaft gets into the oil and causes foaming which are air molecules inside the oil. Air doesn't lubricate very well. See where this is going? On engines with oil pumps, causes more issues like cavitation.

slomo

 

[cprodave]

I removed about 2 ounces of Oil to get back to within Fill Range. I always keep the cooling fins etc clean (although this was a good reminder). I removed the carb, disassembled it--didn't see any obvious sign of Stuck Float but soaked the carb in Isopropyl overnight, blew out all passages and reinstalled. Replaced Air Filter. Still had a problem. Removed/disassembled Carb, found I had the Float Pin partially seated, that was definitely binding up the Float. Reassembled. It ran much better, no longer guzzling fuel although RPM's cycle a bit more than I remembered previously. Big difference in Fuel Consumption--seems to be back to normal. Thanks to All.

 

[Scrubcadet10]

be sure your engine oil doesn't smell like gasoline before you run it anymore.

 

[Hammermechanicman]

Sticking carb needle and seat comes to mind.

NEVER over fill the oil. Keep it exactly at the full mark only. Check oil prior to every mow. There is a reason they put the full mark where it is. Most engines the crankshaft gets into the oil and causes foaming which are air molecules inside the oil. Air doesn't lubricate very well. See where this is going? On engines with oil pumps, causes more issues like cavitation.

slomo

I better take off all those oil dippers on the ends of connectiong rods.

 

[cprodave]

Mower is running fine now. Thanks for the inputs, especially to check for Fuel in the Oil. Oil does not smell like gasoline. I checked Oil "necking" between thumb and Index finder--seems fine, i.e. Oil is not thinned. I had a neighbor who accidentally put gas in his mower's Oil Fill. That did not end well. He is not very mechanically inclined lol.