Jonathan Dyer

iTrader: (5)

Hello. This pic was taken looking up at the fuel lines just forward of the rear axle (driver's side).

There appear to be four lines from the fuel tank. One to the carb, two to the evap. canister, and the last to the white plastic doodad circled in the pic.

Anyone know what this is and if I could remove it and use it as a return lne for a fuel injection system?

Thanks,
Jon

knapper79

Its a breather filter for your gas tank. It is used with evap/purge emission system. If you have removed your evap emissions then you can use it as a return.

Jonathan Dyer

iTrader: (5)

Thanks for the response. Any idea where in the tank this winds up? I'm wondering here about air bubbles in the returning fuel being sucked back into the feed line. Presumably, both vent and evap. lines would need to be above the fuel level to function? If so, why wouldn't the evap. lines be sufficient to vent the tank? Is the vent there as a redundancy against a clogged up charcoal canister?

Finally, I have two evap lines, only one of which is connected to the charcoal canister. The other is capped off. Would this be another possible option for a return line?

Sorry for the amount of questions at this time of night!
Thanks,
Jon

knapper79

Jon,
The vent line opens in the tank right after it enters through the plate. If i remember correctly, it has a check ball to not allow fuel to exit through that line.
In these vehicle, the lines coming from the fuel tank are configured for one fuel supply, one return line, one to evap canister, and one to vent.
The evap canister does have a vent under it. This comes into play when the purge valve is opened, then the fuel vapors trapped in charcoil are sucked in, the vent on the evap can filters the air that purges the canister.
The vent/filter located back by the tank is to allow the vapor to be removed from the tank and "stored" in the charcoil evap can without creating a vacuum in the tank. This is very typical of early design evap emissions. Some very early systems actually just vented through the gas cap. Newer designs do not have an open vent to the atmosphere that is not controlled by a valve.
The capped line in your engine compartment was not meant to go to the evap can. there should be only one line from the tank going there. I would personally want to keep a vent for the tank. This will reduce the chance of creating a vacuum in the tank which can cause strain on the fuel pump and potentially affect fuel supply, depending on your engine fuel needs/configuration of course. If you are not running emission systems on your vehicle, the best idea would be to use either the capped line (which I believe to be the original return line) or the one going to the evap can, or even both (both would only be needed if you are running a fuel injected fuel pump, with a return regulator for carb, on a carburated car).
I am no expert on Fbodies, I actually am just working on my first one now because the wife wants it. However, I do have an undergrad degree in Automotive Tech and am an ASE Certified Master Tech. So all my information is from my experience/training.
I had to trace my lines frmo the tank forward to determine which went where since I bought my TA without motor or any emissions components in it.
Hope this helps, let me know if you have any other questions.

89-bird

Looking at your picture you have three of the four lines going to the tank , one is fuel feed , one is fuel return , and the other is for the evap. If you look at your fuel pump if it is factory style pump the larger line is for fuel feed and the smaller is fuel return . Even if you are not running the factory pump the small hard line near the pump is the return line .

Jonathan Dyer

iTrader: (5)

Thanks guys. This should help alot.
Jon

89-bird

You're welcome and good luck .

five7kid

iTrader: (14)

Looks like all 4 to me. The 4th is the one with the vent valve (no filter).

89-bird

Yeah all four tank lines are there I should have said three of the four hard lines going to the tank .