Nissan NSF4 starts then dies

[Dickytom]

Today. Motor started fine then died. Topped off with fresh gas and started again. Got out into cove and it died again. After several dozen pulls, still would not start. Pulled choke out and it started but ran rough and died as soon as pushed back in. Got back to the slip and started with choke open and let it idle for a few minutes so closed choke and it ran for a while and died. Would not restart without choking.

Just got motor and ran it for almost an hour to get across the lake a couple of weeks ago. used it yesterday for about half an hour with no problem. The only thing I've done to it was take off the cover to blow out and vacuum out a bunch of dirt dobber nests. That was yesterday before using it for half an hour.

Any ideas?

 

[pvanv]

Re: Nissan NSF4 starts then dies

If the motor requires choke to run, it's likely too lean. That being the case, you likely need to clean the carb. If you are not comfortable with removal and disassembly of the carb, see a dealer for assistance. In the future, you must always run the carb completely out at the end of the day, to reduce the varnishing that causes that too-lean condition. If you ran the motor a couple of weeks ago, and did not run the carb out, that's a big clue that the carb is varnished. Today's fuel leaves a lot of residue as it evaporates. The very small passages of the modern EPA-rated carbs clog more easily than carbs of yesteryear. The two situations combine to clog up the tiny passages in the carb.

Also verify crankcase oil level. It must not be over full. Not even a drop. Likewise, make sure you are using fresh fuel -- not more than 30 days old. Most of the gas you buy today will be E-10, which does not age well. If in doubt, dump it out, and run it through the car or whatever.

 

[Dickytom]

Re: Nissan NSF4 starts then dies

Thanks. I'm comfortable removing the carb and cleaning it but my experience is limited to automotive. Is it just a matter of disassembling, soaking, blowing out, and reassemble?

 

[Sea Rider]

Re: Nissan NSF4 starts then dies

If that carb is lightly warnished remove plastic, rubber parts before, spray carb clean on all parts and fuel pasages. Disassemble, clean, soak, blow out, and reassemble is correct. If carb is still factory adjusted and working well, before removing idle mixture screw from base, measure the height from top screw to base with a vernier tool, reinstall when finish cleaning, that way will maintain factory adjustment

Happy Boating

 

[pvanv]

Re: Nissan NSF4 starts then dies

In order to do a proper and thorough cleaning, do a complete disassembly (including jets and emulsion tube nozzle), followed by a 4-hour soak in real carb cleaner (available in 1-gal cans at the auto parts houses), followed by a spray out using generic carb spray. Then do a careful reassembly, paying close attention to float height.

These carbs do not have removable mixture screws. The EPA has mandated that a plug is pressed into the cavity where you would normally access the screw. Because of that, you can't "fudge" by enriching the idle some on a too-lean carb. You must do a proper cleaning in order to restore proper air/fuel mix.

The hard plastic bits stay on the carb during cleaning. Just the soft/rubber items (and float, of course) come off. If you find white aluminum oxide residue in the carb, those parts that are affected should be replaced. In a worst-case scenario, get a new carb. If doing that, consider that you can upgrade to a 6 hp motor (50% power increase) by merely changing the carb to a 6 hp unit for a little over $100.