View Full Version : Yam 40 HP F40 4 Stroke sputters at 1800 RPM

08-09-2009, 08:53 AM
"I have a 2003 40 HP 4 Stroke that sputters, dies back in RPM when it throttle up to 1800 RPM or so and keeps doing it till around 2500 RPM. Idles great, runs wide open great but just cruisng at these RPM's it tries to stall. New water seperator, new gas, carbs rebuilt just before I bought the Whaler in June. Fuel lines look good and sealed. Seems to run smooth through the problem RPM's when I flush it on the trailer not under load.

Any ideas????"

08-10-2009, 03:16 PM
"check fuel pickup check valve in tank, primer bulb, fuel line quick disconnect for leaks of fuel or air, check fuel pump, drain carbs onto clean white rag to see what's in the float chambers, with drain plugs out, pump primer bulb to flow fuel through carb/past float needles. Good Luck!"