Carb 'leaking' through impulse hole

[mikerecike]

Pressure testing a Walbro WT 170 for a friend and air is escaping through impulse hole on side that mates with block and cylinder. New one on me. New carb kit and Welch plug (could he have damaged something with Welch plug change?).Scratching my head.

[GardenKit]

For air to be getting into the pulse bore it has to be passing the pump diaphragm somehow. Have you definitely got the pump diaphragm and gasket the right way round?

[spudulike]

For air to be getting into the pulse bore it has to be passing the pump diaphragm somehow. Have you definitely got the pump diaphragm and gasket the right way round?

 

Spot on, I have seen the area around the cover screw pierce the pumping diaphragm. Use a magnifying glass and a bright light to inspect the diaphragm.

 

It may also be a slight leak around the gasket. Use a little oil around it to seal it and try again!

[mikerecike]

Thanks Barrie and Spud - will take a shufty

[spudulike]

Just had an Echo come in with one of these WT carbs and fuel was pissing everywhere. Took the carb off and big air leak from the impulse line.

 

Took the pumping diaphragm cover off and found the pumping diaphragm was missing the part that does the pumping so am assuming the gasket is used in another model of carb and had been fitted incorrectly.

 

Fitted a spare gasket etc and the saw is a runner again.