Hello, on my 1992 454 motorhome, when i turn the key to on position the fuel pressure builds up to about 12 psi, I can hear the pump coming on then after two seconds roughly the pump turns off and the pressure drops back own to zero. I pinched off the fuel return line and it still does it. I pinched off the feed line after it builds up and it still drops after the pump turns off.

My sources say that pressure should stay up even after two hours. Well, the pump is brand new, the regulator is new and so is the fuel pump relay! The car runs fine. So my sources say there must be a leak either outside or inside the tank but if so why when I pinch off the feed line does pressure still drop?

Any ideas anyone? Thanks for your input ahead of time.

Spanish Guitarist San Francisco Bay Area