Return line to fuel tank

Hi Jack,
Was wondering when you'd get back to that project....seems you are making good progress.

Yes on tapping that port for return.
Industrial and gen set engines have the fuel pressure relief valve mounted at that location with return to the tank. The transfer pump just has a direct feed (no relief valve housing) like the tractors.

By golly, that was fast! Thanks, OM.

I think I can make a fuel line adaptor without the pressure relief and a return line fitting with the relief from the D2 pump fitting faster than I can run down real D311 parts. I just didn't want to do either until I was sure it would work. Everything else on the front of that engine is modified. Why quit there?

No reason why not.....and probably just as well that you make your own as it's none to clear in the parts book for the either the D311 or D315 but clearly shown in the operators manual.

Jack, modern Cat engines have fuel return lines but the older machines didn't have them unless the fuel tank was mounted where the fuel level could get below the fuel pump. Industrial engines could have the tank mounted anywhere so they all had a return line. The return line will return any air picked up by the suction line to the tank and provide Constant Bleeding.
Later Bob