1989 Mercury 80hp 3 cyl

[Glastron1987]

Is this a Mercury fuel pump or aftermarket? I would only trust a Mercury fuel pump.

The zero pressure was on a brand new non-merc fuel pump. So sounds like you're right to trust only the Mercury one.

So the test at the lake proved that the rebuilt Mercury pump had corrected a problem. It ran fine on the external tank at all speeds and sustained it.

When I hooked it up to the internal tank it failed again. So obviously there is still a problem with that system somewhere. I started with replacing the ball and immediately adjacent lines. Recently I had already replaced the pickup tube in the tank and the anti-siphon valve. This all seemed to pump by hand OK, but several locals are telling me to remove the anti-siphon valve entirely... even though it may be brand new they are bad news.

Anyone else have an opinion about anti-siphon valves?

[rock]

Unless your motor is lower than the fuel tank remove it.

Rock