I have a 1986 350 vortech mercruiser that uses a holley marine electric fuel pump. I've been having power issues on and off over the last 2 years. This year it really started to act up. I installed a auto meter marine fuel pressure gauge that uses an electrical sender. When idling up to 2000 rpm,s the gauge shows 5psi. As increase rpm's the fuel pressure drops off till it reads nothing. I idle the engine back down the pressure starts to come back up again. I finially narrowed it down to the anti-syphon valve in the fuel tank. I removed it and replaced it with a regular fitting. The fuel pressure now stays a constant 5 psi under all loads and rpm's. I assume the valve can't handle the flow required by the electric fuel pump. Is there a special valve to use for an electric fuel pump? There was no dirt or anything in the valve. The ball seems to unseat easily with slight pressure.
