I have a 2006 gravely 48z, with a 19hp Kawasaki engine, model no. FH641V with 535 hours on it.
It’s been running lean And getting harder and harder to start requiring a full choke, followed with partial choke even after it’s warmed up. If I back off the choke after being warm, and give it full throttle, it will run but it surges even backfires.
I cleaned the carb finding one clogged jet on left side, cleaned it, reassembled it- but have same issue. So I drained the gas and removed some water in the tank. Ran fresh gas again, replacing the inline filter but it ran the same, less backfiring though.
Carb is tight, no air leaks on engine side or intake side - even tested for it by spraying starter fluid near the carbs while running and no rev changes were noted.
Your problem favors a progressive fuel starvation. Everything from the tank fitting to the carburetor is suspect.
The fuel lines and line fittings will trap debris and starve the engine for fuel. 90-degree line fittings are the worst about this. Lines are often taken for granted to be good, but they collapse internally creating a blockage.
Have you made sure there is no intake to carburetor warpage? Overtightened bolts will warp the intake mounting face for the carburetor. Most can be releveled with a block and fine sandpaper.
Next item that is often overlooked is the pulse type fuel pump. They have the 2 fuel lines, but also a crankcase pulse hose that will crack and split with age. If it is cracked or split the pump will not work efficiently.
Address those items first and let us know what you find and if you could correct the issue.
