16 HP Vanguard blow black smoke at start-up/under load

[RAM56]

Just started last few uses. Just a puff of black smoke at start-up, ran fine, backfire at shut-down.
Now Black smoke at start and under full load. Today can't maintain rpms with load and black smoke under load.

Exhaust pipe is very sooty but dry, plugs heavily fouled.

Hope it's only a carb problem (rich) and not more serious. 20 year old unit with lots (unknown) hours.
Where to start?

Model 303447
Type 0447-01
Code 94030311

Thanks

 

[ILENGINE]

I would start with a good carb cleaning, and go from there.

 

[gregjo1948]

Make sure your choke cable is adjusted correctly and your air intake is clean. Try running without air filter. gregjo1948

 

[RAM56]

Will do tomorrow, Thanks.

 

[RAM56]

Thanks for the advice. Found a video showing how to disassemble and clean the carb. Got it done and reassembled.
New plugs, filters, fresh gas and it runs fine.