Hot start problem resolved due to failed check valve in the DMCH fuel pump

[kings1527]

This is where I get mine:
http://www.mcmaster.com/#metric-o-rings/=p3nifs

I use 1.9 mm X 3.8 mm but I think the stock size is 2.0 mm X 4.0 mm. Either works but I guess the smaller one gets more seal since it has less surface area. Viton is a little harder then Buna-N.

Thanks perfect, thanks for the info Dave. So that'll be the size for the smaller o-ring. Do we know the size for the bigger o-ring? Or does that one prove to not be much of a factor for holding rest pressure when compared to the smaller o-ring?