Rebuilt Petcock, super tight

I am having the same issue. The o-ring is too big. It will barely turn. Now it won't turn off when on Res or On. I have taken it apart 3 times. It works as it should while sitting on the bench. When I hook everything up and run it it starts flowing while on Res or On. It has a rebuilt kit on it. Any suggestions?

I think I figured it out. The diaphragm was not seated correctly - it was kind of off center so it looked like the seal was not complete. I followed the instructions on rebuilding to make sure the passage was properly aligned and that seemed to seat it better. Anyway, I re-assembled and checked it out. No leaking when on Res or On. I went back to the old O-ring as the new one is too big. No leaks and it turns easier so I will stick with it.

One more thing - If I understand this correctly the vacuum pulls the diaphragm away from the seal part so it flows fuel when on Res and On?

tri650 wrote: One more thing - If I understand this correctly the vacuum pulls the diaphragm away from the seal part so it flows fuel when on Res and On?

yep

Update: Had a chance to install the OEM O ring this weekend. It was a better fit for sure, but was still tight. I was able to polish the drum area with my dremmel and got the fit near perfect.