I have a mechanical gauge on my vp44 test port and a electrical westech comming form the fuel filter cap. The hose from the cap to the fire wall where there is a isloator mounted, then the wires to the gauge in the cab. I just put the isolator on the fire wall from having it mounted to the fuel cap(from genos). This is a new isolator the other was giving erratic reading. My question concerns the pressure when I shut off the truck, now it takes almost 1 minute fro the pressure to get to zero. Why? Is it any cause for concern or is due to the extra lenght of fuel line to the isolator? Thanks.

 

Mine drops back to zero as soon as the gauge is turned off. It's slowly returning fuel back down the line into the tank. I really wouldn't worry about it if the gauge if working correctly.