My vst's and mechanical pumps are now gone..Mechanical pump block off plates are on after changing and adding oil to water pumps Fuel rails will come off this weekend and will be shipped to Eddie Young. Will post pic's of process of installing new Aeromotive pumps, filters etc.. But of course this is all predicated on if freaking Ohio can get over -5 deg. Days like that are made for watching offshore boating on YouTube...and drinking cocktails.

I have 1999 502 Mpis with cool fuels and it vapor locks every once in a while if I run it hard and shut it down right away. I have heard about the return line on a few threads but no one has specified what line, where it is hooked up, or how it was run. Can some of you guys take some pics please or specify exactly how this was done? I would appreciate it.

Guys with cool fuels have options unlike those of us with vst's, With cool fuels I think one is a kit from Merc that has some sort of check valve for the cooling water or something.. The other is a plug and play auxiliary elec. fuel pump,,again by merc.. If you search on here you'll find a ton of info.. I can only comment on the VST corrections and even that is a work in progress..guided by EFI gurus. If your issues are minimal the merc options may be quicker and cheaper,,

I'd rather not add anything else electrical, like another pump. Like I said, not a huge problem for me but being in south Texas the summers get a little steamy. Id like to avoid issues in advance if I could and the return line sounds like the best way. I just need to know where the return line connects to the engine. Is it in the cool fuel pack somewhere? Or do you have to hook it up to the fuel rail somehow. I've seen the part that cp performance has and that looks like the best way. Just need to know where to run it on the other end.

My suggestion would be contact Eddie Young of Young Performance., he's gonna have the answers your looking for.

http://www.mercruiserparts.com/Show_...ilter+and+Rail

Fuel line '20' is your return line from the regulator (A) that goes to your fuel separator housing. What is being said to do, is to unhook that end of hose #20 at/and fitting #9 and install a pipe plug in the separator housing to cap off that port. Now add a section of fuel hose to to the end of the fuel hose you just unhooked, and run that new hose to your gas tank, either by connecting it to an unused port on your fuel tank if you have one (should be in area of where the motor feed hose is) or if no unused port, then by insetting a Tee fitting in your main fill hose and connecting the new hose to it. Or if you can replace your sending unit with one that is made for a diesel, as those have an extra port welded to the sender mount to run a fuel return hose to.

At least that's my take.

Awesome. Thank you

Here was my fix. I posted it before. No more vapor lock, no more $85 vent valve, no more washing down #8 with raw fuel, and gas from the vst gets routed back to the tank.

Some tech data-

The mech pump has 1/4" NPT ports
The hard lines are 3/8" tube
The VST has 5/8-18 inverted flare ports
The fuel rail has some proprietary o-ring fittings and a retainer plate

Summit Racing has all the fittings and adapters needed to connect these ports to hose or hard line.

Hi. I'm having a vapor lock problems. I wanna install the check valve on the fuel railing. I just don't know what check valve I should use and where to install it. Can you give me advice please? Or link to the site would be the best.

I modified my VST tank few months ago and thought the problem is gone but now with the hot Florida summer it came back. I think gasses are gathering in the fuel rail because it won't even start unless it's cooled down. Please help.