Curiosity question for everyone.... What was the first year for the fuel return line evaporation emissions control? My 70 El Camino has the fuel pump with the 1/4" return line for the fuel. I have always been led to believe that the first year for this type of emissions control system was 1971. My final assembly date of my 70 El Camino is the 4th week of April. Anyone have any insight on this ?

Brian,
I think in '70 the presence of a return line was determined by which engine option your car was ordered with.
My 3-70 ATL manufactured Malibu with a 350/auto has none.

'69, 395/325 w/ Calif Emmisions had it.

Brian, I remember this being talked about before but not sure of this.I believe for "70" the return line and long style fuel pump were used starting in Feb of 70 in the Big Blocks. Jim.

my '65 has a fuel return line

Jim,

Its entirely possible as my car is an April 70 car with a big block. I know my 71 Buick GS conv. with the GS 350 motor has the return line on it also. Again, since I wasn't certain, I figured I'd ask the pro's on this Q&A forum. graemlins/beers.gif graemlins/thumbsup.gif No harm in asking.

My 70 SS396 has a build date of 4/06 and it also has a fuel return line. Hope this helps.

Had to be before Feb - my 70 SS is Jan third week - had the long fuel pump with the return. It may have been sometime in Jan - any one else with earlier cars who can add to this?

Thks

Rich

Rich, All 70 396-454 A/C cars should have the long fuel pump and return line. Also your 70 SS is a Calif car, and I believe all CA emissions cars had it. Some plants used the 40768 long pump as early as Jan 70. Most all used it after late Feb 70 on.

I posted an informative reply on this topic somewhere on this Tech Forum. Try a search on LS6 vent return line.

70 with bigblock, return line, no emissions (canister) lines at all. Built in Feb. None of that matters anymore cause its getting all new stainless tube tech lines, a rock valley stainless tank with tpi pump and a Ramjet 502 :D

I always thought the return line was to combat vapor lock. I fail to see what it could do for emissions if you don't have a vapor canister. My 69 camaro had the return on the fuel filter. It's been plugged at the tank since the 80's. I've never seen a requirement to have it installed. Back when I cared about passing a CA smog test. I went to different shops looking for loop holes to get mine to pass. Each shop had a different book with different footnotes. smile.gif Figured out I could swap the thermo air cleaner from the Camaro to the El Camino so I wouldn't need to buy an air injection setup. Just depended on the shop.