Daskuppler Posted October 28, 2020 Share Posted October 28, 2020 Hello Everyone, I have a 2002 Impreza TS with 120k on it. Recently, I have been having issues filling the gas tank. When fueling, the pump shots off after about 3/4 gallon if on full flow. From what I've read, this is likely something to do with the EVAP canister which is $125. I know they are on there to control fumes and meet EPA compliance. Is there a way to bypass them or are they essential for the engine to operate properly? It seems like one could simply disconnect the breather hose from the fuel tank or at the canister and it would solve the problem in exchange for a thrown code. Thoughts? Thanks, Andrew Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 28, 2020 Share Posted October 28, 2020 disconnecting hoses is one way to troubleshoot the issue. Could be the 'drain' valve is stuck or it's hose plugged with spider/wasp nest or ??? the worst case, the evap valves built in the top of the tank are stuck. the evap system changes from model year to model year and you need to find the diagram for your model. has the car sat unused for a long period of time or has it regularly been 'topped-off' when filled with fuel in the past? 1 Link to comment Share on other sites More sharing options...
Daskuppler Posted October 28, 2020 Author Share Posted October 28, 2020 It is not driven terribly frequently, but never sits for more than two weeks. The car is not typically topped off as long as I've owned it (since 2011). I'll look for a diagram and see what I can figure out. I have a scope camera as well so maybe I can get a sneak peak into the hoses and such. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 29, 2020 Share Posted October 29, 2020 (edited) you can connect diagnostic wire under the dash and force the solenoids to cycle, at least you'd know it can operate. if topping-off when fueling has been mostly avoided, the carbon canister is unlikey to be flooded so, 'drain' hose or valve is the problem, or the tank valves I think. On some systems, the 'drain' is a 2-way deal. Under normal circumstances, it lets outside air in to compensate for the lower tank volume as fuel is used-up. I guess it also allows air in when the purge valve opens? During fueling, it allows fume-laden air to enter the carbon canister and fume-free air (after the carbon adsorbs the fumes) to escape. it's complicated and there can be some differences between year models. Others may explain it better. Edited October 29, 2020 by 1 Lucky Texan Link to comment Share on other sites More sharing options...
heartless Posted October 29, 2020 Share Posted October 29, 2020 had this happen on my 2002 Forester - of course it happened in the dead of winter, too.. in my case, it was a bad case of rust in the small hose connections attached to the filler neck.. as in rusted completely shut so vapors could not move around. I would not expect that in Colorado, but i suppose anything is possible. there is also a small "switch" thing attached to the filler neck, up fairly high, that can be purchased separately.. called a "fuel shutoff solenoid" for me, replacing the entire filler neck, including the above mentioned solenoid, was the answer/cure. The replacement filler neck i purchased came with the solenoid already on it. fwiw, i do have a cel for the evap canister solenoid located at the charcoal canister and the car runs fine, and takes fuel fine, so i do not believe that particular unit has anything to do with fueling.. I do have a new one here, but getting to the old one, and getting it off.. yeah.. major rust monster involved, which is why it has not been done. 1 1 Link to comment Share on other sites More sharing options...
Daskuppler Posted October 30, 2020 Author Share Posted October 30, 2020 12 hours ago, heartless said: had this happen on my 2002 Forester - of course it happened in the dead of winter, too.. in my case, it was a bad case of rust in the small hose connections attached to the filler neck.. as in rusted completely shut so vapors could not move around. I would not expect that in Colorado, but i suppose anything is possible. there is also a small "switch" thing attached to the filler neck, up fairly high, that can be purchased separately.. called a "fuel shutoff solenoid" for me, replacing the entire filler neck, including the above mentioned solenoid, was the answer/cure. The replacement filler neck i purchased came with the solenoid already on it. fwiw, i do have a cel for the evap canister solenoid located at the charcoal canister and the car runs fine, and takes fuel fine, so i do not believe that particular unit has anything to do with fueling.. I do have a new one here, but getting to the old one, and getting it off.. yeah.. major rust monster involved, which is why it has not been done. Thank you for the input. I definitely need to look at it and see what I can find. It's annoying to take 10 minutes to fill the tank! If the car had been topped off, I presume the excess fuel flows into the canister; would the fix be to drain the canister or are they damaged for good at that point? Link to comment Share on other sites More sharing options...
heartless Posted October 30, 2020 Share Posted October 30, 2020 10 hours ago, Daskuppler said: Thank you for the input. I definitely need to look at it and see what I can find. It's annoying to take 10 minutes to fill the tank! If the car had been topped off, I presume the excess fuel flows into the canister; would the fix be to drain the canister or are they damaged for good at that point? i would think it would depend on how often it happened, and how much got in there.. but at this point, i would be investigating the filler neck & associated lines before worrying too much about the canister itself How i found out mine was all rusted up was when I tried to pull one of the small lines from that shut off solenoid to see if it made any difference.. could not do it.. they were rusted that badly. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 30, 2020 Share Posted October 30, 2020 I have read the the FSM has a weight limit for canisters? - if they are too heavy with fuel, they get replaced. Not cheap. The system in newer cars is supposed to limit the chance for fuel to get in there but....???? Link to comment Share on other sites More sharing options...
heartless Posted October 31, 2020 Share Posted October 31, 2020 yeah, i think you may be right, but that assumes one get even get it off to weigh it, lol the older Legacys had the charcoal canister under the hood.. much harder for fuel to actually get into them. The forester it is in the back, UNDER the tank... Link to comment Share on other sites More sharing options...
Daskuppler Posted October 31, 2020 Author Share Posted October 31, 2020 2 minutes ago, heartless said: yeah, i think you may be right, but that assumes one get even get it off to weigh it, lol the older Legacys had the charcoal canister under the hood.. much harder for fuel to actually get into them. The forester it is in the back, UNDER the tank... If I identified it properly, it is sitting under the rear bumper right next to the tank. If it is not rusted, it should come off pretty easily. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 31, 2020 Share Posted October 31, 2020 I'd consider pulling hoses off the canister while filling, to somewhat prove it was bad. there may be 2-3 hoses on it so, you really need a diagram. Link to comment Share on other sites More sharing options...
heartless Posted October 31, 2020 Share Posted October 31, 2020 11 hours ago, Daskuppler said: If I identified it properly, it is sitting under the rear bumper right next to the tank. If it is not rusted, it should come off pretty easily. and there you have the reason I have not even attempted.. RUST! i can pretty much guarantee you mine is not coming off easily, lol I live in Wisconsin, where cars rust away around you long before they quit running, lol Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 31, 2020 Share Posted October 31, 2020 (edited) We have seen the canisters blow up and carbon pellets get sucked into all the lines and into the fuel tank. We have had to pull out fuel tanks to clean them and the inaccessible vent valves on top of the tank. Last one was a 2003-ish Forester. Similar era and system. GD Edited October 31, 2020 by GeneralDisorder Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 1, 2020 Share Posted November 1, 2020 (edited) 10 hours ago, GeneralDisorder said: We have seen the canisters blow up and carbon pellets get sucked into all the lines and into the fuel tank. We have had to pull out fuel tanks to clean them and the inaccessible vent valves on top of the tank. Last one was a 2003-ish Forester. Similar era and system. GD GD - no chance of 'reverse soaking' or somehow flushing the top valves of the tank? Seems like they just gunk/varnish up and some fuel-safe solvent, and maybe a little persuasion with an air hose or ??? might pop them loose. Anyway, my MIL's Forester had that happen (she used here car very intermittently) and it took a LOT or persuasion to get Subaru to replace the tank. Edited November 1, 2020 by 1 Lucky Texan Link to comment Share on other sites More sharing options...
GeneralDisorder Posted November 1, 2020 Share Posted November 1, 2020 19 minutes ago, 1 Lucky Texan said: GD - no chance of 'reverse soaking' or somehow flushing the top valves of the tank? Seems like they just gunk/varnish up (she used here car very intermittently) and some fuel-safe solvent, and maybe a little persuasion with an air hose or ??? might pop them loose. Anyway, my MIL's Forester had that happen and it took a LOT or persuasion to get Subaru to replace the tank. We tried every conceivable resolution. The customer certainly wasn't excited about pulling the tank. Ultimately we had to pull the tank after the car came back for about the third time unable to fill the tank and with codes, etc. GD 1 Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted November 3, 2020 Share Posted November 3, 2020 This is a good thread with some great pics illustrating some of the crazy valves and piping involved in the fuel tank's operation; https://www.subaruoutback.org/threads/whats-inside-fuel-tank-edition-leaking-fuel-tank-autopsy.510193/ Link to comment Share on other sites More sharing options...
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