turbom700

You should never have vapor lock issues if your return fuel to the tank, wont matter where the pump is mounted.

BUP

iTrader: (9)

Still will have the issue of heat soak / fuel boiling off especially at the electric fuel pumps that are mounted very close to the engine on a 115 to 120 degree day very high water temps with a marine engine offering no cool fuel and no water check valves after engine shut down that causes a no start condition hours later on the water.

Electric fuel pumps hate to pull fuel they rather push fuel and stay primed. Once the fuel boils off some electric fuel pumps check valve will stick. Just saying. Fuel pumps in the tank is the best way to avoid some of these problems. Wakeboard boats / engine apps have been doing this now for years offering no cool fuel and electric fuel pump(s) in the fuel tank.

There is a reason why Merc mounts their Gen 2 and newer Gen 3 cool fuel and electric fuel pump(s) very low is because the bilge itself is the coolest area temp wise in the entire engine compartment.

The VST was a bad design and mounted on top of the engine - 2 mistakes with that system right off the bat..

Good post # 10 about running the blower and trying to get incoming air to your fuel pump also mounted low and not on the engine - the coolest area of the engine compartment - the bilge. Some of these HP aftermarket electric fuel pumps do a better job than what the OEM installed.