Evinrude 50 starves on full throttle.?

Question

I have an old Evinrude 50 which has been running fine until recently. I got the powerpack and water pump replaced and was advised that the motor was in great conition for its age and is running about 165 psi per cylinder. I had it on the water today and at full throttle it seems to starve for fuel. I replaced the plugs and all fuel hoses and it's still the same. It idles fine and seems to have a problem when placed into gear. Any ideas? I' realise that it will probably need to go into the workshop but was hoping i could grab an opinion before I do.

Answer 1

Obvious things to check include replacing the fuel filter (if you have one), and condition of the carb. If you can, run a tank or two of very high detergent Top Tier premium gas like Shell V-Power Premium or Chevron Techron Premium through the engine, to dissolve gum. These fuels have 5x times the detergent of normal EPA mandated fuels, and do a good job of cutting varnish and deposits in the fuel system.

Ignition timing can also cause poor top end performance in 2 stroke engines, as can exhaust issues, and both can mimic fuel leaning condition, as intake velocity drops due to increased back pressure, and the effective mixture actually is leaner than optimum.