Posts: 3480
Location: Elk River, Minnesota | Hiya,
A pull of the plugs could tell a bit here. If they are running dark, it is receiving too much fuel. If running white, lean.... This is just a quick start to begin isolating the issue...
I would start with some of the easy, preventative maintenance things as mentioned above: Fuel filter and plugs. If he is running a fuel/water separator, that would be something to swap out as well. If there is no change, see if you can use a separate tank and hose and take the motor out and retest. If no change, then the problem is isolated to the motor. If performance goes back to normal on the separate tank, the problem is fuel line related.
In many cases, what you describe can in many ways be a tell tale sign that carbs are in need of work... Not sure if your's is efi/throttle body or not, but if it is carbs, that would be my next thing to go to after changing out plugs and fuel filter, check for leaks, and no change in performance.
This is just a start, and hopefully with the couple of quick things, performance will come back.
Steve |