My 1996 7.4 mpi has the dredded vapour lock issue, it has the vst tank and no cool fuel tank. So whats my best option here, The 1996 has the mechanical fuel pump on side of engine. Some say to add a electric fuel pump and filter ( 6 to 8 psi ) from gas tank to mechanical fuel pump line. Also a return line to fuel tank. Would this electric fuel pump setup work and what else do i need to stop the vapour lock. Thanks
electric fuel pump by
Carter P4389K Universal Marine Electric Fuel Pump Kit 6 psi (max pressure)

Are you sure it's a '96? I have two '96's and neither have the pump on the engine block but rather the mechanical lift pump sits on top of the sea water pump housing.

Removing VST Fuel System - 502 MPI

Need to add fuel booster pump for 454 mag mpi, what psi?

Keith

You are correct,its the mechanical lift pump sits on top of the sea water pump housing. Yes it a 1996 454 lx mpi 330 hp. I read your posts and links. There is a kit on ebay i'm going to get / electric fuel pump 6 to 8 lb pressure from tank to filter to the mechanical pump. Question how do i run a return fuel line to tank or do i need to? Thanks for your help.

Before you go into modifying the system check the VST itself. There is a diaphragm inside the top cover of the VST that will deteriorate over time and create a situation that APPEARS to be vapor lock but IS NOT. This is an easy and relatively simple fix.

I have not done the conversion but I see some run the return fuel line to the fuel filler hose rather than the tank.

Keith