I recently installed a 4bbl intake and a Holley 4160 on my trucks, with a stock output mechanical fuel pump. From reading things that the stock pump puts out too much pressure, I installed a regulator (Holley 12-803), and on one of the out ports I put a fuel pressure gauge to monitor pressure.

When hot, I only have 3 psi at the gauge and the clear inline filter barely has any fuel in it. I originally thought it may have been some of the bends in my system, so I re bent and re plumbed all the 3/8 hardline and fuel hose. No dice. Got maybe 1/4 psi difference at the gauge.

When I start it, I maybe get 4 psi but then after 1 minute idling, it drops off again.

I'm thinking its a bad pump, because I also have another fuel filter before the pump and it stays full of fuel, but the one just before the carb just goes dribble dribble.

But I am also wondering, do I need to have my gauge in series with pressure? Is fuel flow like electricity? Do I have it hooked up wrong?

Here's a picture of my regulator set-up. Top=from pump, left = output 2 (gauge), right = output 1 (to carb)

 

A regulator shouldn't even be needed with a stock mech. pump (unless you're running an Eddy carb), the stock pumps only put out about 5-8psi.

My first guess would be faulty pump, or possibly a bum regulator.

 

Your gauge is correct.

 

Got a new pump in the geh-rage actually. Thanks for the input gang