what is??

[NickSpider]

I am in the process of changing out the fuel pump and all the fuel lines. In the trunk next to where the electric fuel pump goes there is a white plastic piece that has fuel lines running through it. Is this another fuel filter? How many fuel filters do I need?

[So Cal Mark]

what year? if it has more than an in and out line it's probably not a filter

[baltobernie]

You didn't state what year and model you have, but it sounds like the three-way valve that controls evaporative emissions in the fuel tank. They are very fragile and not available in the aftermarket, so don't go gonzo tightening hose clamps or mounting ears on this item. Sometimes they get plugged by debris; there is a tiny orifice on the rear (facing forward) allowing air pressure in to compensate for the gasoline volume being consumed by the engine. Take note of the orientation when removing this item from its mounting holes; there is an "in" and "out" nipple, and it is possible to incorrectly reinstall without first marking "up" or similar to assist you.

[NickSpider]

You didn't state what year and model you have, but it sounds like the three-way valve that controls evaporative emissions in the fuel tank. They are very fragile and not available in the aftermarket, so don't go gonzo tightening hose clamps or mounting ears on this item. Sometimes they get plugged by debris; there is a tiny orifice on the rear (facing forward) allowing air pressure in to compensate for the gasoline volume being consumed by the engine. Take note of the orientation when removing this item from its mounting holes; there is an "in" and "out" nipple, and it is possible to incorrectly reinstall without first marking "up" or similar to assist you.

1975 124 1800. It is a clear to milky thing that is screwed to the side of the trunk right next to the fuel pump, On fiat parts warehouse they call it a two way valve, what is the significance of this? Do I need it? Where can I purchase a new one, since the one i have is cracked?

[baltobernie]

We're talking about the same part; I guess the correct name is "two-way". You need it if you have all the evaporative emissions equipment installed and working in your car. I'd try Bayless for a salvage part.

[NickSpider]

We're talking about the same part; I guess the correct name is "two-way". You need it if you have all the evaporative emissions equipment installed and working in your car. I'd try Bayless for a salvage part.

i am in the process of removing all the emissions components...air pump and all hoses and valves attached. So from your statement is sounds like I will not need it if these components are no longer functioning?

[mdrburchette]

The fuel system on these cars are sealed so that valve aids in keeping the pressure correct for the fuel tank. You have lines going to a canister that is mounted in the left quarter panel. This separates the fuel and fumes. The fumes then travel to this two way valve and to the evaporator cannister in the engine compartment. I don't think it would be wise to remove that valve.

[perthling]

I don't think it would be wise to remove that valve.

If you have (for example) replaced th original tank with a replacement out of a Euopean coupe or similar, then you lose the additional vent pipes on the top left of the tank. So to allow the tank to vent (ie expand and contract and not burst) you can either drill a small hole in the centre of the filler cap, or put a little hole (or tap to a fuel filter etc) in the overflow return tube.

Once the emissions control stuff is removed the canister in the left rear of the trunk is only giving you the ability to vent the tank effectively. With the original tank you could just run one of the vent tubes to a fuel filter or similar, mounted high up under the wing, to save yourself some weight.

Agricultural I know, but it works.

[So Cal Mark]

Perthling, do you really want the tank vented inside the trunk? It seems like a good way to fill the area with fumes

[launieg]

I apologize if I am further confusing this topic, but I am certainly puzzled. For my 81 FI, the manual shows two valves between the tank and the charcoal canister (which is in the engine compartment). The first valve has three lines to/from the tank and another one heading over the the cannister. This valve is very obvious, located above the tank in the wheel well.

In the manual, this is labeled as "vapor/liquid separator". I can see that one tube allows fumes and vaporized gas to come up from the tank and then the liquids are shunted back down the second tube to the tank, while the fumes rise and head over to the cannister through the upper (fourth) tube. But why a third line going up/down from the tank? Does this somehow equalize the tank pressure? What is its purpose, or do I have a wrong picture of what is happening?

Then, the second valve (labeled as the "two-way valve") is further along toward the canister. What does this do? I could see it possibly being a one-way valve (check valve), preventing flow back toward the vapor/liquid separator", but how and why is it "two-way"? By the way, I cannot see this valve in my car. Is it hidden away?

Again, I realize there must be variations depending on year, but I would truly like to understand what is happening, so I can test for "working right". I am now worried about tank pressure, not to mention fumes going in wrong directions.

Sorry about hijacking this topic in my own interests, but maybe some of this stuff is common to all years. Does somebody understand this stuff thoroughly?

[manoa matt]

That check valve is located above the rear axle. There are also several rubber lines that connect sections of hard line by the drivers side rocker panel, check these for leaks.