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1978 280z what is this Filter Looking in fuel line?

February 20, 20196 yr

Vapor vent or one way valve, I see my confusion now, my unit blows through in either direction. Thanks guys, you solved a problem that I didn't know I had.

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February 21, 20196 yr

comment_568965

On ‎2‎/‎19‎/‎2019 at 7:20 PM, grannyknot said:

most of my 280z knowledge comes directly from Bruce.

Too... much... pressure.......

You guys don't need me here. You got this! :beer:

But just because I'm here, here's a couple other threads that talk about that check valve:
https://www.classiczcars.com/forums/topic/60827-where-is-the-fuel-vapor-check-valve-located/?tab=comments#comment-558365
https://www.classiczcars.com/forums/topic/58221-starting-problem/?page=5&tab=comments#comment-528408

12 hours ago, grannyknot said:

Vapor vent or one way valve, I see my confusion now, my unit blows through in either direction.

It's supposed to blow through in both directions (some check valve, huh). The trick is that it's supposed to blow through EASIER in one direction than the other:

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February 25, 20196 yr

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comment_569345

On 2/20/2019 at 6:34 PM, Captain Obvious said:

Too... much... pressure.......

You guys don't need me here. You got this!

But just because I'm here, here's a couple other threads that talk about that check valve:
https://www.classiczcars.com/forums/topic/60827-where-is-the-fuel-vapor-check-valve-located/?tab=comments#comment-558365
https://www.classiczcars.com/forums/topic/58221-starting-problem/?page=5&tab=comments#comment-528408

It's supposed to blow through in both directions (some check valve, huh). The trick is that it's supposed to blow through EASIER in one direction than the other:

ive given up.. i dont know where to buy a replacement? do you guys know? thanks

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February 25, 20196 yr

comment_569386

20 hours ago, cclxxxz said:

ive given up.. i dont know where to buy a replacement? do you guys know? thanks

You don't need it for engine operation. It's an emissions device. Edit - the following statement is wrong >>> Any check valve will work.

Cool. I've discovered a new trick.

Edited February 26, 20196 yr by Zed Head

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February 25, 20196 yr

comment_569389

If this is what you are speaking of, from what I remember. Fast woman found one on ebay for a diesel, "sam the dieselman"

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February 26, 20196 yr

comment_569413

That one is for fuel. "280" is looking for the vapor line check valve.

Actually, I was wrong in my earlier comment. Not any check valve will work. How it works is shown in the FSM drawing. Two way, like CO said.

It's kind of redundant as far as the fresh air flow backward to the tank since the gas tank cap has a vent also. If you do change it to a check valve make sure that it lets air out. The filter that's on there is probably the best "fix" until you find a real one.

But it's not really going to affect engine performance.

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February 26, 20196 yr

comment_569455

Yeah, I'm not exactly sure why then needed that device in there at all in the first place.

When the fuel vapor expands, you want it to push into the carbon can. It will do that with just a hose. When the fuel vapor contracts, you want to prevent a vacuum on the fuel tank, and there's already a check valve built into the filler cap that will prevent that.

I haven't looked into it, but I'm unclear why they thought they needed that fancy unbalanced two way check valve at all. Maybe they wanted to run "a little bit" of positive pressure in the tank to help out the fuel pump?