I'm an old carb guy, so excuse my ignorance.
Does merc use a fuel cooler on all their EFI motors? How about other manufacturers.
I'm asking to see if an EFI system without a return line to the tank is going to have issues without a cooler.

if you aren't runing the return line to the tank but just back to the filter that fuel is going to be very very hot in short order w/ no cooler. i would run it back to the tank even if it HAD a cooler

I have cool fuels on my 502mpi's and still get some vapor lock on 100* days.

all the late model engines that dont use a VST tank use a fuel cooler and return the fuel back to the filter.

Yeah, I was thinking that would be the case.
Unfortunately this is a strait IB setup. There's about 15' of bulkheads, stringers, flooring, a bed, head with shower sump, etc with limited access between the motor and the fuel tank.
And judging by their prices, Merc is REALLY proud of their cool fuel setups.

All you need is an inline cooler, similar to a p/s cooler. You will need at least a 2" X 8" to keep the fuel cool. Ideally, you want to run it to the tank, but it doesn't seem possible. You could also do a small tank to pull from to help give the fuel time to cool down. You would only need about a 2-3 gal. tank. You could return to it and let the engine pull from it. You would still need a cooler, but you shouldn't have any vapor lock problems with it.
Eddie

Did the VST setup ever work well? Wasn't it basically a carb bowl/needle valve with an EFI pump in it?
I'm actually asking this for a different reason. I put an LS2 EFI motor in a 68 vette, no sump or baffles in the fuel tank. I'm thinking the a VST setup might be a "bolt on" solution to fuel starvation/slosh without having a custom tank built.

Damn, I just did a search and found this. I thought I was the fist one to think of this idea...
http://www.vetteweb.com/tech/vemp_07...tem/index.html