ORIGINAL: simonr23
i have a nitro sport w/ pro.15. today i was driving it around and it startes to hesitate when accellerating mildly after about 1/3 of a tank. on the next tank it was hard to start and then wouldnt rev out for about 1/4 tank. then in just an instant it seemed fine again for about 1/2 tank. finally it started hesitating when accellerating till it ran out of fuel and i gave up for the day. any ideas what could be causing this? motor compression seems fine, carby well tuned, not running lean either. thanks for any help.
The inconsistencies you describe are a common symptom of an air-leak. Replace all lines first off. Blow through the new pressure line while keeping the line that feeds the carb sealed off, that way you can make sure that the tank isn't leaking. Also ckeck to make sure your cooling head and carb neck are tight. If this still does not fix it, you will have to pull the engine and seal the carb neck and back-plate with some type of gasket sealer like RTV (you can get it for 2-3 bucks at any auto parts store)...