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Replacing EVAP line going from charcoal canister to gas tank

mattd1205

mattd1205

Member
Joined
Dec 5, 2014
Location
Harbor City, CA
Smog check time is coming up on my 1991 245. It blows clean every time but the evap seems to be the weakest point on my car. I?m thinking of preemptively replacing the brittle plastic line that goes from the charcoal canister back to the gas tank since that?s how they got me last time. Is there an ?off the shelf? auto parts store solution to make this happen?
 
It helps a little if you tank is full so that the analyzer doesn't have to pressurize a lot of volume.
 
In my experience the plastic fuel line isn't usually the issue. Split rubber hoses connected to the plastic line are more common. Smoke testing a car that failed the evap test but otherwise looked fine revealed a leaking roll over valve so be sure to check that as well.

Another place to check is the filler tube. Early cars had a problem with the nipple for the evap hose coming loose and all cars can suffer from out of round filler necks from jamming the gas pump nozzle down so it will stay in place for hands free filling.
 
He has a '91 which is a late 240. I l always had a problem getting a good tight seat from the generic threaded pressure adapter being fitted in the filler neck. STANT eventually designed a right adapter that is a proper fit for 240 Volvo. As long as the tech is using it and is pinching the proper EVAP line it is not likely to fail.
 
dbarton said:
I'm not certain of the size needed, but something like this should work. Other sizes are available.
1/4" OD x 50' Black SAE J844 Nylon Air Brake Tubing, $20.99.
https://www.amazon.com/Mytee-Products-Nylon-Tubing-Approved/dp/B075LWC96J?th=1
Nylon can handle fuel or fuel vapors. Just be sure NOT to use vinyl tubing found in the garden section at Home Depot.
Dave B
Click to expand...

I got underneath the car and you were right. It?s quarter inch line. Great price for peace of mind. Thank you so much Dave!
 
hiperfauto said:
In my experience the plastic fuel line isn't usually the issue. Split rubber hoses connected to the plastic line are more common. Smoke testing a car that failed the evap test but otherwise looked fine revealed a leaking roll over valve so be sure to check that as well.

Another place to check is the filler tube. Early cars had a problem with the nipple for the evap hose coming loose and all cars can suffer from out of round filler necks from jamming the gas pump nozzle down so it will stay in place for hands free filling.
Click to expand...

Thanks Hiperf! I?m probably going to replace the little rubber fittings as well since I?m there anyway. These smog checks are getting spendy so I hope to get it 100% right the first time.
 
I just started trying to replace this same line this past week. I have a 1976 242. I know I have one line going from the charcoal canister to the gas tank, but then I had two lines coming up with the filler neck into the trunk, both pinched and melted. They then run to a check valve looking thing mounted up in the right corner of the trunk area. One seemed to be just hanging out not connected to anything. Does anyone have a diagram for these evap lines from the gas tank to this check valve setup?
 
http://hiperformanceautoservice.com/images/EvapControls1.jpg
EvapControls1.jpg
 
dbarton said:
I'm not certain of the size needed, but something like this should work. Other sizes are available.
1/4" OD x 50' Black SAE J844 Nylon Air Brake Tubing, $20.99.
https://www.amazon.com/Mytee-Products-Nylon-Tubing-Approved/dp/B075LWC96J?th=1
Nylon can handle fuel or fuel vapors. Just be sure NOT to use vinyl tubing found in the garden section at Home Depot.
Dave B
Click to expand...

Updating this thread in case someone else is dealing with smog check hell due to bad evap lines. This stuff worked really well. The smog test went fine and passed the evap portion of the test with this line without issue. I was left with enough to do the car a second time. Thanks again Dave!

As a side note: I used 5 feet of 1/4 fuel line from autozone to replace all of the original junctions between the canister and filler neck.
 
I gotta get a 1991 740 thru CA smog due to failed evap. I smoke tested my system with Redline machine and couldn't find any easy to spot leaks.

Are they putting pressure, or vacuum in the filler neck for the test? I failed for a 0.001" leak...
 
its pressure...
and the easiest way to pass is disconnect the hose at the filler pipe and replace with a short plugged hose
also always go with a full tank so the test goes way faster
and the smog dudes don't give you stink eye for wasting all their tank
 
philski o'flood said:
its pressure...
and the easiest way to pass is disconnect the hose at the filler pipe and replace with a short plugged hose
also always go with a full tank so the test goes way faster
and the smog dudes don't give you stink eye for wasting all their tank
Click to expand...

Damn I replaced all that evap line for nothing? Argh.
 
at the charcoal canister they pinch off the hose that runs back to the tank
and then pressurize the tank... and the roll over valve and the lines back to the canister
to see if anything is leaking. If you just remove the line at the filler neck and plug it
all that is tested is the tank

vac-B21A-F_B28_1980evap2lo.jpg
 
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