Nissan 99 runs good one day bad the next

"The type is an NS9.9C. Change

"The type is an NS9.9C. Changed the fuel, cleaned the fuel filters, checked the plugs. Adjusted the carb setting to closed, then one and a quarter turns back then tweeked it to perfect from there. It hums... Next morning, it's back to it's old tricks. Try to put it to half speed in neutral and it wants to die. I get the same results for reverse and forward. The thing will start on turtle throttle setting and run all day... and everytime. I have manual and electrical start, and an external tank.I use it to power my sailboat near shore and the dock, and it has to be dependable. Any suggestions?
Thanks... Steve"

Sounds like a fuel system prob

Sounds like a fuel system problem. Get out your service manual and work your way through that system.

"I actually ended up tearing a

"I actually ended up tearing apart the carb, cleaning it and checked the float... and was a little dissappointed to find every thing very clean. With everything I did, I now find the carb setting at about 1 3/4 from closed position seems to work fairly well.With the cavitation forming in the garbage can that I'm trying the engine in, I find it hard to carry a constant rmp, so I guess I'll have to try it at the lake.

Wish me luck... Steve"