I am retrofitting a carbed 502 to a used stock 502 MPI set up. I have read that some people have had issues with vapor lock on boats equipped with the VST tank.

Would installing a small PS cooler and plumbing the return fuel line thru it and back to the VST be worth a shot? I know the preferred way would be to rig a return line to the tank, but it just isn't practical with three tanks.

thanks in advance for your replies

Steve

it depends on what you want to believe. if you believe that the fuel from the tank being too hot is the issue, then maybe. i can't see how that is likely to be the case. ive never measured it but i would be hard pressed to believe that the fuel is hotter than ambient... but maybe i suppose. and , honestly, the greater fuel density of cold fuel is a good deal anyway. having said all that, i believe most boat vapor lock issues are manifold and fuel rail temp related . the intake manifolds roast and the fuel rails get hot enough to boil the fuel in when they sit and heat soak... thats the problem, i believe.

you solve that with good ventilation. i think the fuel cooler deal is more about using the fuel as coolant for the fuel rail
( greatest delta T ) and trying to cool the components that way...

but thats just a theory.

No I do not believe that the fuel from the tank is the issue. I think the heated fuel is created from two problems: one, as you stated is the engine heat cooking the fuel. Secondly, the fuel going around in circles at low engine speeds, (no wake zones on hot days) getting hotter everytime it passes through the fuel pump. That's why I thought a small PS cooler might do the job.

I have thoiught about this myself. I think it is a great idea and would work well in regards to cooling the fuel and hopefully take care of vapor locking as well.

Good luck and keep us posted on the results.

I converted my factory cool fuel system years ago with a small 100$ oil cooler to increase capacity,works great,Smitty

I took mine off and returned to the tank to free up some room. Do you think I should put it back on in my application?

this is what I had in mind



http://marineengineparts.com/shopsit...roduct104.html

That looks exactly like what I used,Smitty

The answer to your question is this, if it's working fine right now by just sending it back to the tank then you are golden. If it vapor locks or acts up then put it back on. I know in my application at wot NO fuel is being returned to the tank,Smitty

I'm scared of WOT!