Gas Powered Roof Pump and Metering Valves

Recently purchased a 6.5 gpm roof pump AR-25 with 1" suction line, does great batch mixing. But will not build pressure when tied in to my 1/2" DYI metering valves with 1" manifold. All fittings are tight no air leaks . Do I need bigger metering valves ?

Yep, 3/4” or 1”. I believe 1” is what a lot of guys use. Not on the soap though. Well that’s on the bigger gas pump, so….yours is smaller. Not positive on that.

what engine are you running?
Im currently looking to build a roof pump using the 6.5hp predator eng

Briggs & Stratton. Vanguard. 6.5hp. With A/R 25 pump

Do it, you will not regret.
I have exactly this setup with predator 6.5.
Works perfectly.
I use it at 2800 - 3000 rpm.
Have it for almost 2 years and no issues.
I have 3/4 inlet and return hoses from my 55 gallons drum.
Im still using batch mix , but will upgrade to a DIY proportioned soon.