I need to know what size O-Ring is used when modifying the pump to go from the Walbro 255 to the Walbro 400/450?

Not getting any fuel pressure and it seems the supplied O-rings are ineffective







Thanks!

 

no pressure? What kind of sock do you have on it? Could it be that your hitting the bottom of the tank and blocking the inlet?

 

put the stock one back on. The supplied sock blocks the inlet.

 

I had a feeling, glad you figured it out.