Is the vapor separator canister really needed?

[b5blue]

  Vapor separator canister on big blocks, I ran my 6 pack for years without one but installed one when I set the fuel system up to correct. Now I'm switching to a CH4B intake and Proform 750 with a Carter M6903 fuel pump and thinking if it's not needed why keep the extra plumbing.  I'm not using headers and never had any vapor issues in 20 years. Anyone have long term advise from experience?      (I'm just simplifying anywhere I can.)

[Dino]

I put 4000 or so miles on my car without the canister.  After upgrading to the canister and bigger fuel line + return line and putting another few thousand miles on it, I can honestly say the difference is...just not there.   

Never had issues without the can or with a single 5/16" line.  I simply upgraded because my lines needed replacing sooner rather than later, but I honestly doubt it's making any difference at all.

[green69rt]

The car would probably run fine without the return line 99.99% of the time.  I think the vapor separator is insurance that you wont have trouble that other 0.01%.  I'll be driving in Texas on hot summer days, maybe in heavy traffic.  My car will have the return line.  There is no maintenance so not a big deal to me to have it other than the initial cost and installation.  I have heard that folks on this site have had problems with them, usually installed wrong, or the return orifice is missing or too large so it robs gas from the carb.

The problem I see is that if you don't have the return and nothing goes wrong then you would think you never needed it.  But, if you have it, and it's doing its job, how would you know?  Again, you might conclude that you don't need it.  It's that 1 in 10,000 chance that you get vapor in the gas line and you don't have the separator that you think "wish I had it" when the car stumbles or dies.

[cdr]

green69rt is correct!!!!! especially need if your car has a/c, the little i ran my car last summer without a return, in traffic it would fuel surge from boiling fuel in the lines, when new engine goes in it will have a return.

[Sublime/Sixpack]

Take this for what it's worth; I had problems years ago with the fuel in my '69 Super Bee's fuel line turning into vapor (I'd basically run out of fuel at WOT at the top of first gear and into second). I added an electric fuel pump near the tank to resolve the issue, which it did for the most part. But eventually I tired of the noise of the electric pump so I pulled out the single 5/16" fuel supply line, installed a 3/8" supply line, plus a 1/4" return line, modified my fuel sender unit to accept the larger fuel line and return line, then added a fuel filter (that is similar to  Mopar's fuel separator) just before the mechanical pump. It worked so well that I was able to do away with the electric pump. And have never had a vapor lock problem with this car since.

Went through a similar scenario with my '68 Coronet 318 2 bbl. car. On a hot day after sitting at a red light for a minute or two when I'd take off the car would sometimes run out of fuel (vapor lock). I added a return line, modified my fuel sender to accept it, and installed a fuel filter with the additional nipple on it for the return line. No more fuel vapor lock problem.

Unless today's gasoline (at least where I live) is under pressure (EFI set up) it tends to turn to vapor quite easily when hot. I'd keep the return line and fuel separator. 

[b5blue]

Thanks for the feedback!