I have twin 502 mags, later models with cool fuel on the side of the block, just replaced the fuel pump and regulator on one. Getting 70 psi at the rail, return line isn’t clogged and vacuum line isn’t pinched. Has anyone had this happen before? Don’t really wanna pull the motor to replace the regulator again. Any advice would be appreciated greatly

Did you put on Mercury parts or ? after market parts are like a box of chocolates

oem parts

Poor location design by Merc, are you testing pressure at the schrader valve and the gauge is accurate ? if so Id say you have a bad reg.

The problem might be the screen item 16. If the screen clogs up, there is no return
Most remove it
Screen

I agree with all Dodge. Anytime I get a high-pressure scenario on any motor, I check the screen on the return line 1st. It should be right under the regulator on most motors

if not,then the regulator was made by the guy who cast's sb's sbc exhaust manifolds.lol

yup. Fk’rs cant even engineer and cast sbc chevy exhaust manifolds.
True statement