help! stovepipe separator - with diagrams

[myraley]

Hi guys. I have trouble with acceleration off idle sometimes and so I started looking at the fuel pump, and then the fuel lines and I realized most of the lines had been cut and capped off. I also realized I have this fuel seperator thing back by the rear driver side (not far from the gas cap). I looked at the assembly manual, and it looks like I ought to still have all these lines connected. Can somebody help me out? What does this do? Is in necessary? and what about the return line from the fuel pump? That would have gone to this separator but it is capped off too. Is that important? Here is what the lines looked like originally.

[myraley]

And here is what I have now. As you can see, everything except the line from the tank, to the pump, to the carb has been cut and capped off. Why? Why did the previous owner make things so hard for me???

[89 crew]

p.o.'s make things hard because they don't know any better. The up side to this, is we get a lot of good trucks because people mess them up on stupid things like this.

[myraley]

I know what you mean, but man, I wish the list had been shorter. Parking brake cables, distributor, heck, windshield wipers. And then I've to figure out whether to fix it or not, like this fuel line thing. I'm thinking I should at least re-connect the return line from the fuel pump, but since it goes to the separator, that means having to reconnect all the lines. Say, there isnt charcoal or anything inside this separator, is there? I read about the canister with charcoal that some cars had, but they didnt have that in 72- 75, did they?

[89 crew]

I have no idea. you could take it off and see if it weighs more than a plastic can should. if it is full of charcoal it should be excessively heavier.

[71RestoRod]

The stovepipe you are describing is a vapor tube. It's part of a vapor recovery system that was introduced in '71. It is actually a good thing to have hooked up. It is an emissions device but passive in that there is no pump robbing power from the engine. The engine burns the vapor that would otherwise be released to the atmosphere. It's no big deal to disconnect the system the way the PO did as long as the gas cap is replaced with a vented cap.

Your diagram is missing one component, the vapor canister, which mounts on the front of the right fender next to the battery. If the PO didn't disconnect and cap off the vacuum line from the carb to the vapor canister you might have a vacuum leak going on, but there are obviously a lot of things that could be causing the hesitation you're describing.

I might be wrong, but I don't remember a return line on the fuel pump. It might be capped off because it's simply not the correct pump. The second hard line was for vapor recovery and routed back to the vapor tube.

If you're interested, the following link provides a plumbing diagram and past discussion regarding the vapor recovery system.


http://67-72chevytrucks.com/vboard/s...d.php?t=187860

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[jaros44sr]

Good information, RestoRod. You've convinced me to go back and hook up that part of the system that was not hooked up....J.

[myraley]

That is good info! I'm going to connect mine up too, but I also dont have the canister up front. Can I leave that part out, as I have an aftermarket Holley carb anyway and dont have a way to connect it to the carb? Or is it necessary for the separator to work properly? If so, I will route... which line to it? The return line?

[71RestoRod]

You need the canister to hook it up. You can buy them new through LMC and I'm sure other vendors but pricey @ ~$100. Junk yard is your best bet and the replacement filter for it is cheep. There are three lines that go to it, all different sizes. The smallest line goes to a ported vacuum on the carb and controls a valve in the canister. The medium sized line hooks to a tee in the PCV inlet and the large one routes down the frame to the vapor tube.

[myraley]

Hmm. The only ported vacuum I have on the Holley carb is going to my distributor advance. The PCV connection shouldnt be a problem... I looked in my assembly manual for a diagram of this canister and hose routing and couldnt find one. Can you draw up a diagram or do you have a page from a manual that shows this routing? I'm gonna have to get creative. Oh, or can you take a photo of your engine compartment? That would help me. Thanks!

[tdkosta]

I don't know if this picture is going to help at all, but I think this is the canister you wanted a photo of. It is located right next to the battery.

[JayDubBlazer]

Is there a different canister you can use so you don't have to run a return line all the way back to the from on the vehicle?