fuel pressure

[dec010974]

hello to all. im having a problem with keeping fuel pressure @ 6 psi. my setup is a 1971 c10, with a carbed lq4/th400. the regulator is set @ 6 psi. my msd 6010 ignition box has pill #6. im also using the stock in cab tank, with a new 3/8 in. sending unit, while running a holly blue fuel pump and regulator. when im ready to start the engine i push the throttle/gas to squirt fuel into the carburetor. when i crank the engine, its run until the fuel runs out. eventually my fuel pressure drops to 3 psi. this happens all the time(fuel pressure drop). when the engine is cold, fuel pressure starts at 6 psi and then drops as the engine runs and shuts off. what could this be? before i sell off my kids to fund the rest of my hot rod project, i would like to trouble shoot this problem but just dont where to start. if you can, please chime in and help a c10 trucker out. im totally open for suggestions.