alright, swapped out the in pump sending unit from the 90 GTA. Swapping in the 1982 carb sending unit. It has four lines in it. Obviously one is for the fuel pickup, two are just open right at the top of the unit, like for vents, and one is for a vent with a check ball kind of thing. I am hooking up the pickup one to new fuel line I am running, and I am to assume that i need one for vent. Should I use the one with the check valve and can I just run a line up and backwards and leave it open for vent. I left the stock vent line open at the front of the car on the MeanYellowZ and it was fine, so wouldnt this be the same thing, just vent back by the rear of the car. If I should use that line for vent, then I can just plug off the other two line openings right, the two that just open up right at the top of the tank.

any answers?

 

You could plug all of them and use a vented gas cap, or yes, vent one at the back and plug the other two.

 

bttt, anyone else?

 

The vented gas cap is great, but you probably want a vent off the tank as well to aviod gas burping up while fueling.
The deal with the check ball, might be the return line. The two other line at the top of the unit are the vent & vapor. The vapor is to catch residual vapor for emission purposes.(I think it runs to your charcoal canister)
If it helps, most fuel cells on race cars only have a vent & pickup.
You might want to use the return line if you will have previsions for it. ie. regulator or fuel pump. It takes a little stress off your fuel pump.
If you ever see Nascar, you'll notice that they have the vent exiting the rear, and a guy with a catch can to grab fuel burping out as the dump 22 gallons in 15 secounds.

I hope that helps a little.

Ron


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'82 Trans Am
'81 Camaro Z-28
'94 Vette LT1 Coupe

 

for some reason i am thinking the check valve one would make a good vent because it appears it would close itself off in the event of a rollover

anyone else????????????!!!!???!?!?!

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Currently own: 2001 Xtreme, 85 IROC, 87 S10
pics of my old 86Z:
Camaro1 Camaro2 Engine
More at: My Directory
Email: MeanYellowZ@hotmail.com Aol/IM: RCY1980

 

Again, I think that check valve is for the return line so It would only flow into the tank, not out. They do put a little filter looking deal on my '82. It's right next to where the four lines couple from the tank to the car.

Just do what I'm going to do, and drop in a real 22 gallon fuel cell. They have a big 'o' check ball, to keep fuel from coming out of the filler neck. I'm not sure what they use to stop fuel from coming out of the vent. Oh well, I'll find out when I get around to buying and installing one.



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'82 Trans Am
'81 Camaro Z-28
'94 Vette LT1 Coupe

 

fuel cell idea sounds great except the hatches in these cars suck and we already have a sub, NOS and a battery back there.



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Currently own: 2001 Xtreme, 85 IROC, 87 S10
pics of my old 86Z:
Camaro1 Camaro2 Engine
More at: My Directory
Email: MeanYellowZ@hotmail.com Aol/IM: RCY1980

 

Sorry to dig up an old thread but just thought you might like to know. If the one with the check valve is 3/8" it is the vent to atmosphere and has the white plastic valve under the tank when installed. This is to bleed off excessive tank pressure and prevent fuel spill in a rollover. Vented gas caps only let air in, not out. Why would there be a charoal canister if the tank can bleed pressure through the cap? The short open 5/16" line is the return and the 1/4" line is for the emissions charcoal canister.