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'71 Unconnected lines and capped tank connections

2558 Views 7 Replies 5 Participants Last post by  suprdave1
I searched on Gas Tank connections and have read most of the posts, but I haven't found a satisfactory answer to my question.

Today, I installed new shocks and springs on my Chevelle and as I was doing the work under the car, I remember seeing in the documents provided with the car that the fuel tank had been replaced about two years ago. I noted that there are connections on the tank that are capped and the only connected line is going to the engine area. I'm assuming this one connected line is the line providing fuel to the engine. There are other lines on the car just above the differential that are disconnected. I haven't traced these yet, but my review of posting on the forum indicates they are probably going to a canister behind the backseat or in the trunk.

I've only had the car for two weeks and the engine is a Blueprint 383 stroker and has only been in the car for about a year. The motor runs and performs great. After I bought it, I filled it with gas and parked it in my garage a couple of nights. My wife and I noticed a gasoline odor occasionally. This is a concern since my gas hot water heater is in a closet with vented doors off the garage. I also recalled the previous owner parked the car in a carport but told me he had noticed when filling the tank that as he took off the gas cap that the tank sometimes builds pressure.

I'm thinking I need to connect the unconnected lines above the differential to the connections that are capped on the tank, but I do not want to foul up the fuel system that is currently functioning properly.:unsure:

I'd appreciate any guidance or input from some of you experienced Chevelle owners. I'm thinking you might actually help me avoid an explosion in my garage. I'm not parking it inside until I get this issue resolved.

I'll look forward to your responses. As always it is most appreciated.🙂👍
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Do you still have the charcoal canister in the engine compartment? It would be behind the left headlight.

Can you look at the front top of the tank and tell us how many fittings you see coming out of the tank? On a 71 or 72 you will see 1 on the right front, 1 in the center, and one on the left front. There will also be a 3/8 fuel line running from the top of the tank, from the fuel pickup/sender tube, to the engine.

Do you see a series of 4 pipes coming from the axel hump area ahead of the tank just above the rearend.? They lead to an area behind the back seat.

Let's see what you have. There are a few ways to tackle this. Some will offer some relief, but the best setup is the full 71-72 vapor recovery system.

Currently, it sounds like you are not running any type of vent. You can build pressure or vacuum depending on conditions. The pressure can force fuel past the needle and seat of the carb when parked hot. The smell will be coming from the engine area and is most noticeable if you have an open element air cleaner. This will also lead to starting issues in hotter weather.

View attachment 699507
I have just restored my 1971 Chevelle. I installed a Pro Flow fuel injection system. I did not need the vapour lines or the charcoal cannister, so I took them out. I capped all the vent holes in the tank and rear cannister with rubber vacuum caps and put on a vented gas cap. I also made sure that where the filler tube meets the gas tank is sealed because when I installed the new tank I had to make adjustments. No gas smell and all works as it should. Now if you are using a carburetor then you probably need the vapour lines so the steel lines are an easy install and do things as shown on the drawing . The line from the charcoal cannister to the carb may require revision.
71-72 Fuel tank vapor line kit.
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