18 Nissan 2 Stroke Falloff at WOT

[JCN]

I ran my 18 Nissan 2 stroke recently for 1/2 hour without any problems then all at once the RPM's fell off at WOT and it continues to do so at any RPM above Midrange. The motor starts and idles fine and runs great through mid-range, getting my boat on plane, then "bogs down" once I push to WOT. Any ideas here as to a cause or where to begin?

 

[pvanv]

Re: 18 Nissan 2 Stroke Falloff at WOT

What is the model? Sounds like time to clean the carb... but could a restricted fuel filter or weak fuel pump. Troubleshoot fuel delivery and clean the carb first. Then let's see what we have.

 

[intrepidvoyager]

Re: 18 Nissan 2 Stroke Falloff at WOT

fuel supply or bad fuel ...... bad fuel in tank ...ok at first but then h2o mixes with fuel ...problem ..... also check fuel water separator and fuel lines ...blockage in squeeze bulb etc ...make sure you are not creating a vacuum as in tank vent ... if problem persists ...either dirty carb or fuel pump.

take carb (s) apart and blow carb cleaner thru every hole incl main jet mixer.....make sure choke is not causing problem ...... if problem gets better replace the carb ...if not replace the fuel pump. ..... if problem gone ...yahoo:

 

[intrepidvoyager]

Re: 18 Nissan 2 Stroke Falloff at WOT

re looked your symptoms ..."bogs down" sounds ominously like fuel pressure.

the fact that it was running at WOT kind of iliminates advance ...but check anyway ......also make sure (engine off ) that your throttle plate will open completely and is not binding somehow.....

most "will not go to full RPM" problems are either advance or fuel pressure.

try pumping the bulb just when it starts to bog to see if it picks up ......then its the pump for sure.

can you take the fuel pump apart ( don't know your specific engine ) if so clean it out ...you may have some dirt in the one way valves. you can get an electric fuel pump from a wrecker for next to nothing and use that to supply fuel to the carb ....good to have around for moving fuel anyway !!

Good luck!