Got a fuel pressure enigma that is baffling 1972 Monte Carlo with a 402 the car has run flawlessly for 3 years on a rebuild ( 9to1, small cam, fact intake and exhaust manifolds) at about 3500 rpm, the car falls on it's face and pops out the carb...classic fuel starvation. Changed the fuel pump( stock) and problem still persists. Hooked up fuel press gauge- 4.5 psi at idle and at 3500-4000 rpm under load, press goes to zero and pops out the carb. Changed the pickup and sock in tank, all new now. Problem is still present. Inspected the factory 3/8 steel fuel line- all good. Blew fuel and vent lines with compressed air, no blockage noted. Checked the fuel filter in carb (one of the first things checked) no dirt, changed it anyways.
Carb is factory Rochester rebuilt by jet performance in cal. Idles and accelerates perfectly.
This car ran perfectly and pulled hard to 5500rpm for three years, ran low 14's consistently.
Any ideas would be appreciated