evaporative emissions renewal

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miker
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evaporative emissions renewal

Post by miker » Thu May 09, 2019 1:40 pm

I have never touched my evaporative emissions system, and I suspect it is not working. I develop a vacuum in the gas tank after a long drive, there is a woosh! when I open the gas cap.

All the bits are there, but I suspect the check valve (even at $110, unavailable).

Has anyone retrofit their '77ish to the later system? Those parts are available, and pretty inexpensive.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
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bartigue
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Re: evaporative emissions renewal

Post by bartigue » Thu May 09, 2019 3:37 pm

Sure, it's really straightforward. Look at the system on the 79 - not all the vacuum lines, just the tank/canister stuff, and it's very simple. The "pull through" type canister they used in the later years does a good job and you won't end up with the tank pressurization issue.
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Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
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miker
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Re: evaporative emissions renewal

Post by miker » Wed May 15, 2019 4:51 pm

I have the two diagrams side by side (before/after 1978). The valve I have is listed as "check valve/pressure relief valve" and the simpler replacement is just a "check valve". Is there something else in the later system that serves as a pressure relief, e.g., would I need the later canister? The last piece, the separator, seems much simpler in the newer system.

Midwest Bayless suggests that I might just have collapsed vapor hose, since they are original. I recall that when I changed all the active fuel lines, I avoided the vent lines because KD said that nylon check/pressure relief valve is really fragile at this age.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
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davedecker4
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Re: evaporative emissions renewal

Post by davedecker4 » Sat May 18, 2019 11:08 pm

Yes, if redoing the system you should replace the hoses with new ones that wont be collapsed, cracked, swollen or leaking.
That would be the most important part.
Dave Decker
a 'couple' Fiats and Lancia's
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miker
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Re: evaporative emissions renewal

Post by miker » Wed May 22, 2019 9:54 pm

Does anyone have a photo of the trunk area with a 78+ evaporative emissions setup? I have the new parts, but I'd like to match the original placement as much as possible. The new bits are a fraction of the size of the original.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
paulc
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Re: evaporative emissions renewal

Post by paulc » Wed May 22, 2019 10:23 pm

Our 79 looks like this:
Image
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miker
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Re: evaporative emissions renewal

Post by miker » Wed May 22, 2019 11:46 pm

Thanks! It looks like a simple metal strap is all I need.

Is the check valve back there hidden too? Or is it under the car?

BTW, I found this interesting article about how systems designed around this time are supposed to work. It explains why it doesn't matter which of the tank vent hoses goes to which of the three ports at the bottom of the separator.

https://www.allpar.com/fix/fuel/evapora ... ntrol.html
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
paulc
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Re: evaporative emissions renewal

Post by paulc » Thu May 23, 2019 4:25 pm

Never saw a check valve. The hose thru the strap goes thru the rear bulkhead with nothing else attached, IIRC.
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jseabolt
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Re: evaporative emissions renewal

Post by jseabolt » Mon May 27, 2019 7:49 pm

I was just discussing this on the BS section awhile back. Check it out if you haven't already:

https://www.mirafiori.com/forum/viewtop ... 16&t=98509
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