Re: new Nissan 4hp failure
Welcome to the world of buying mail order: No warranty card filled out, no PDI, no discussion with the customer about operation of the motor. This is an instance where a bricks-and-mortar dealer may have served you better, by giving you a PDI (pre-delivery inspection) and counseling you on the proper use of the motor. For your nearest "real" servicing dealers, see
http://www.nissanmarine.com/search/index.html They should be able to help you, and (depending on the date of sale) may be able to do that PDI at no cost to you.
It sounds like you have a problem in the low-speed circuitry of the carb. While there could possibly be a bit of manufacturing debris in the fuel system that was accidentally left there by the factory, odds are (since it ran well initially) that you did not run the carb dry at the end of your previous session. That is critical on any modern carbureted 4-stroke (of any brand), as the EPA now requires emissions so low, that the passages are so narrow, that today's poor gas tends to varnish up those passages as it evaporates. The rule is to run the carb out at the end of every day. That way, there isn't any fuel in those passages to varnish up. After a week or 2 of sitting with fuel in the carb, the damage is done. In most instances, a thorough carb cleaning (requiring complete disassembly of the carb and a 4-hour soak in carb dip) will correct the problem. Of course, damage caused by poor fuel is typically considered operator abuse, so the work may not be covered by warranty.
Also, always run fresh fuel. If you expect that the gas may sit for 30 days, add a good stabilizer, such as K-100, to help delay fuel spoiling. While that won't help varnishing, on these small internal tanks, it can help the fuel stay fresher longer.
