Unmolested 1971 EEC system??? - If it matters, 402/400TH with A/C

[71CHEVYSHORTBED402]

Finding it somewhat difficult determining the factory EEC configuration for my 71/402/AC project truck. I'll be reconnecting it with the rebuild.

For what it's worth, the story is I bought this truck in 89 with 90K miles. Other than paint & a missing stove pipe, to my knowledge the truck was truly "unmolested" less unseen repairs, which there couldn't have been many.

In 1993 we R/Rd' the engine rebuild and removed the vapor canister & A/C. If I recall, the A/C was working less a possible charge. At the time we installed a valve on the end of the vapor line. I can't say if the vapor canister was connected per factory, but if I had to guess it was.

Unless I'm off me rocker (quite possible), since then the vapor line has been connected to the fuel pump. Can't say for certain, because I often used a mechanic (oooops, wasn't raised around a wrench).......I think the original fuel pump was a single port from the tank, and since then it was replaced with a dual port pump for a return line.


Anyway, some questions please & appreciate any responses. The first image is how I found my fuel tank. It's consistent with the second image below (for A/C, non-A/C, both?)..............Course there may be factory variances.

1. I was informed because this is an A/C truck the sending unit should have had two lines to minimize vapor lock. My other truck (72 A/C) has a dual line fuel sender, but the vapor assembly and canister was removed. That and the tank is unlike my 71.............Anyway, if the sending unit is supposed to have two lines, I'm assuming both run through the cab floor. Beings there are just two holes in the cab floor, can you describe how the tank is connected to the vapor canister?

2. On the flip side, I'd be a bit surprised to learn my sending unit had been replaced at some point. That and by the looks of the filter sock (yikes). My gut says the fuel sender is correct for this truck (doesn't mean it is). To me that would mean there was never a return line. One 3/8" line was run from the tank to the fuel pump, & one 5/16" line was run from the tank to the vapor canister.

My 1971:



Matches this (A/C, non-A/C, both?)