What would cause the primer bulb to stay indented? When I crack the carb (break the tank seal) it will restore nicely. Nevertheless, it will not restore normally. Engine is fuel-starved (but if you give it a vigorous shake, it will catch and fun on for a moment.

Steve, July 2008

Sounding more like a diaphragm fault....

phil_saunders@bigfoot.com

Phil Saunders, July 2008

Phil, Joe.... Thank you. Will puddle more. Another clue: Engine runs well until it has used about an eighth tank of fuel. Primer bulb will restore (slowly) in that time.

Steve, July 2008

After checking feed pipes (unlikely if breaking the diaphragm seal sorts it), replace the following in this order (costs pennies) ;-

1) Replace primer. It may be 'soft' due to age.
2) Replace carb diaphragm. (holed, or work-hardened)

If still no joy, there will be a stuck ball valve in the carb body (the only moving part apart from the throttle valve). Some sharp taps with a hard object on the carb body will sometimes make it free up. As a last resort, try carb cleaner (carefull - prolonged exposure will melt the plastic). Failing that, you will need to replace the carb.

phil_saunders@bigfoot.com

Phil Saunders, July 2008

sounds to me like the screen btween the tank and carb is blocked did you try removing it to see if its blocked?
if so and its not blocked one of the tubes is blocked by dirt or old oil bulid up

JoeP, July 2008