Fixing to install, 2nd gen lift pump on my 1991.5 CTD and went and ordered all the parts-pump, fuel line, gasket, spacer, and seals from Case today.(thanks BC847 for a great write up). Saved about $40 vs going to Cummins. Anyway, ready to order the Sim-Flow bypass regulator and it is prompting me for fuel line size of 3/8" or 1/2". All the existing fuel lines are in place on my truck and/or factory. Which size do I need 3/8" or 1/2". Also what if any additional fittings will I need for the regulator.

 

3/8" will be plenty.

 

Where are you ordering the regulator from?

 

x2, i have been looking for the Sim-Flow regulator that was talked about here i the past and am having a hard time finding anyone who carries it any more.

 

Try www.vulcanperformance.com he told me yesterday he makes them up as per order for either size line.