You would be better off to run the return line back to the tank and forget about the fuel cooler.
Eddie

so the fuel cooler is after the regulator and only used with no return line? So your saying if i put a return line to the tank i dont need a fuel cooler anywhere in the system? sorry i need more explaination or pics lol, im a visual kinda guy. thanks for the help

Tear off all the fuel system including the mech. pump and install the biggest water seperator/filter you can find then the A1000 then a inline areomotive filter. Next you will need a Tee to run one line to the aux. injectors (if you use them) and one to the back of the fuel rail where you can adapt into one of the exiting merc. lines. You can use the other rail fitting if you braze a steel AN fitting on after cutting the hose part off.

After all that you can mount a 3 or 4 port efi reg.( mallory makes a nice one) and bring the two return lines (one from the rail one from aux.) into the body and put the fuel pressure sender in the spare hole. Then out and to the tank. Simple no doable yes. If your serious I can mail you my old fuel fitting to you as I changed out to a new rail.

I'm trying to remember if there was something I had to do with the raw water pump braket when I took the mech. off or was it when I went to a Gen. 6. man I'm getting old.

You should not run a return line back to the tank. Not Coast Guard approved and IMO a really bad idea. Why would you want to take a chance at building up vapor pressure in the fuel tank ?? We are talking boats here, not cars !!! Whole different set ups.

Every EFI engine I build and install(and that is a lot) have a return line running back to the tank. Most boat builders that install an efi engine other than a Merc. run a return back to the tank. I don't know about it not being Coast Guard approved. Not trying to argue Smitty, but I have done this more times than I can count. Nortech, Hustler, Skater to name a few all run the return to the tank. It is the best way to go. With the larger engines and fuel pumps, you have a problem keeping the fuel cool at low speed since the pump moves the same amount of fuel as it does at wide open. The pump has no idea what the rpms are and it pumps the same.

That is correct Conquest, if you run a return to the tank, you do not need a fuel cooler. The tank will cool the fuel. It really only heats up when it is run in a constant loop, like when it is returned to the filter head or suction side of the pump.
Eddie

Running the return back to the tank made my system much more trouble free...vapor locking issues are gone. As far as Coast Guard approval, I can't see why the system would be any more dangerous than a fuel supply line...my boat has the fuel tank vented to the out side of the boat, like most boats. Even though the fuel cooler "isn't needed", why not employ it on the return line?! Say your tank is low, you could heat up 5 gallons of fuel in a jiffy. Fuel coolers on the return to the tank are now standard on the Duramax and I'm sure others. I've done no quantitative testing on this, but the cooler is already there, if you feel it flows enough fuel for your application, I would use it. I'm sure that Jim @ AZ-Speed has plenty of expertise, I just don't think many of his customers benefit from it. Take Care, Dave

I think more important on the saftey aspect is to run the fuel pump relay off of the org. electric pump wire or run thru a oil pressure switch.

sounds good im not going to run a fuel cooler, my VST doesnt have one to begin with so no need to spend more on that if i dont need it. right? and im not going to run the aux. or enriching injectors either, so im guessing i dont need to TEE of the system, right midwest? thx for the help

i was talking with my dad at christmas dinner and we were trying to figure out a way to make the actual return bung on the tank with out taking out both tanks? any ideas or ways you have done it?

I've done several. They are still running fine after 5-6 years with zero supercharger related problems. Of course setting them up with the new fuel system will work very well as long as you use a wide band 02 and tune it on a dyno and the water.