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I hope someone has an idea for me. I have a 2018 RTZ L54 KH FAB that is driving me crazy. It suddenly runs very rich with black smoke and misses. I have changed the filters, plugs, fuel filter and pump, coils, checked it didn't skip timing, checked valve lash, and new carburetor with new solenoid all to no avail. Strange thing is when I disconnect the kill wire from the coils and shut off the ignition it runs better. Not good but better. Help

Check air filter for replacement. Pull dipstick & see if you have gas in oil.

mechanic mark said:

Check air filter for replacement.

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Replaced it already

mechanic mark said:

Check air filter for replacement. Pull dipstick & see if you have gas in oil.

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No. Oil is good. Can't find anything mechanically wrong

Grassman69 said:

No. Oil is good. Can't find anything mechanically wrong

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I did however find I have no continuity on the ignition switch between L and A2 in the reverse position. Any thoughts ?

Grassman69 said:

No. Oil is good. Can't find anything mechanically wrong

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He meant pull the oil dipstick and SMELL it for gas.

Pressure test carb. Specifically the needle and seat here. Carb needle should hold 7psi for 30+ minutes with a WET needle. Spray some PB Blaster on the needle first.

All those "new" parts will require testing.

Hope you are keeping your old parts. Most are probably good.

slomo said:

He meant pull the oil dipstick and SMELL it for gas.

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I understood and did just that

One question out curiosity. Does the ignition switch itself graphics on it of a mower in reverse? Someone could install the wrong switch.

But this has nothing with the running rich problem.

Are the valves moving proper? Time to pull the valve cover and see. Push rods where they belong?

There are 2 TDC strokes on a 4 stroke engine. Could of set valves wrong.

Something is getting missed. Or some "new" part is not working proper.

I checked and adjusted the valve lash. It was almost perfect anyway. I agree, I'm missing somthing and darned if I can figure it out !

UPDATE. I found the problem and I feel really stupid. The new carburetor came with the wrong gasket which allowed it to suck gas directly from the bowl. Installed the correct one and it runs like a champ

do a cylinder balance test.

sgkent said:

do a cylinder balance test.

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He already got it running.