As A64 mentions, at this point we do not know if it is even a 4 stroke
or a 2 stroke motor
, so any guesses are completely that.
When we know a model number and an age then we can begin the stabbing in the dark in earnest!
About the only universal troubleshooting I can suggest for both motor
types is to use an ignition timing light on the spark plug
lead while running and just look at the flashing it does. It will be rhythmic but if a sputtering under power is caused by ignition the change in the pattern of the timing light is quite obvious.
You can narrow down fuel issues by giving the engine
a couple whiffs of starting fluid when it is struggling. If it blazes to life then you can start inspecting the fuel delivery
system. If it is a 2 stroke
you can also give short puffs to isolate vacuum leaks
, especially crankcase seal issues.
In the meanwhile, all we can really do is wait patiently for some engine