Vapor Canister Venting Noise August 27, 2018, 06:09:48 pm Is whining from vapor canister vent hose normal?Do others have trouble filling tank from non vapor capturing type gas pump?Is high pressure in gas tank when unscrewing gas cap normal - I'm guessing some but how much?Is intermittent gas cap burp normal - I'm thinking not but?Background:I was idling the LD Sunday just before exercising the gen set since it hadn't been started in a few weeks and noticed a high pitched whine from driver side. I also noticed a burp or two from the gas cap as I was about to crawl under to see where the whine was coming from. Thought I was hearing things but it definitely burped again.The whine was coming from what I've since learned is the vapor canister. I put my finger partially over the "long" vent hose and it quieted the whine so that was definitely the source. It was sucking air vs "venting" air thru the vent hose.After finding the noise source I checked the gas cap to see if it was secured. There seemed to be a lot of pressure being released as I unscrewed it but honestly I can't say that's not normal since normally the truck is off when removing the gas cap. The whine went away after removing the gas cap but returned (though not as loud) after replacing it. I shutdown the truck to exercise the gen set and to research the thing causing the whine.The truck seems to run fine - no check engine light and no codes on the UltraGauge. The tank is above the 3/4 full mark.A couple things I noticed on our last out-of-state trip in July are:* had to get the pump handle just right to pump fuel without it constantly shutting off if not using CA type vapor capturing pump handle.* once the engine died just after crossing one of many bridge (wash) transitions on I-40 in NM - about 1000mi into our 3500mi round trip. It wasn't a particularly bad/bumpy transition. No code or nothing - engine just died. I pulled over and checked under hood and under truck for leaks but nothing obvious. It fired right up and ran great for the rest of the trip.I read topping off could cause issues with the vapor canister and I could be guilty of this at least once I can think of since the dang pump kept shutting off before I thought it was full at first fill up in AZ. Lesson learned after that.I'll get a new gas cap as precaution for the burp - plus could use a back up since the tether on current one is loose and chances are I'll leave it behind one of these days Will monitor the whine to see if it continues or intermittent but am wondering if others have noticed these noises.Rich
Re: Vapor Canister Venting Noise Reply #1 – September 01, 2018, 03:29:21 am Quote from: Rich Meek - August 27, 2018, 06:09:48 pmIs whining from vapor canister vent hose normal?Do others have trouble filling tank from non vapor capturing type gas pump?Is high pressure in gas tank when unscrewing gas cap normal - I'm guessing some but how much?Is intermittent gas cap burp normal - I'm thinking not but?I suspect somethings failed in the evaporative emissions system that is allowing excessive pressure buildup in the tank.Occasionally, I find a gas pump that is hard to use but not often.A little pressure release is normal if the outside temps are high and you have driven a lot of miles. Burping is not normal and neither is noise from the evaporative canister . Modern gas caps are not vented and since your cap has pressure building up behind it, I would assume it's OK.The canister vent and purge valves, along with the PVC valve, are the first things I would check.Larry
Re: Vapor Canister Venting Noise Reply #2 – September 03, 2018, 03:55:23 pm Went down a few rabbit holes to get there but in the end am fairly confident the EVAP system on my 06 MB is working and the vapor canister vent whistle/whine is more a nuisance than emissions issue. Will find out for sure in Apr when next emissions tests is due or sooner if EVAP code is thrown and/or CEL comes on.I removed the canister vent tube and blew thru each end before and after cleaning it to insure there was nothing in it. It whistled so am thinking it is normal at certain air volumes due to the acoustics of the plastic corrugated tubing.* 01_vapor_canister_vent_line.jpgI still have some doubts about the gas cap venting or not given Larry's comments (thank you) and web research as noted below but I installed a new one and will monitor.Here's a summary of references and observations I came away with after emerging from the EVAP and OBD I vs OBD II rabbit holes.1. OBD II emissions certified vehicles should have these EVAP components * fuel tank pressure sensor (FTPS) * canister purge solenoid (CPS) * canister vent solednoid (CVS) * charcoal vapor canister * Video references ** How your EVAP system works ** Evap Sytem - How It Works * Text Reference ** FORD'S EVAP SYSTEM: OPERATION & TESTING ** Ford 96 thru 2018 OBD II Theory & Operation2. My 06 MB is OBD I certified per sticker under hood on left side of cab * 02_06MB_obdI_cert.jpg3. Ford 06 OBD I systems use the same data link, connector, and PCM software as OBD II systems with some modifictations for OBD I calibrations: * Reference: 2006 MY OBD System Operation * EVAP OBD I mod: "...Fuel tank pressure sensor and canister vent solenoid may be deleted."4. Attempt to identify EVAP parts on my 06 MB * FTPS - 03_ftps_maybe_.jpg ** Not found but suspect this is it on the tank if it exists based on videos and diagrams referenced in 1 * CPS - 04_vapor_canister_purge_solenoid.jpg ** matches Rock Auto vapor canister purge valve / solenoid * CVS - Not found and don't think there is one ** looked for Rock Auto vapor canister vent valve/solenoid ** I traced the vent from the tank to the vapor canister to the intake but could not locate the CVS ** 05_fuel_tank_vent_line.jpg: it's not at the tank since no power going to vent line at the tank ** It's not on the canister per pics in previous post where it should be per videos and diagrams in 1. Plus there is no power going to anything on the vapor canister. ** 06_dog_house_cps.jpg: the only solenoid or anything with power on the vent line is in the dog house at the intake which must be the CPS vs the CVS ** The 2006 MY OBD System Operation referenced in 3 says it may be deleted5. Test set up * Added these gauges to UltraGuage (UG) * These were the only available UG gauges to monitor the EVAP items of interest ** Evaporative Purge % (Evap %Prg): Commanded Evaporative Purge percent. A value of 0% is no flow, and a value of 100% iswide open maximum flow. This is a commanded value indicating that the ECM is requesting ** Evaporative Vapor Pressure (Evp PSI): This pressure value is normally obtained from a sensor located in the fuel tank or a sensor in an evaporative system vapor line. * installed new gas cap Motocraft FC1061 * removed and cleaned vapor canister vent tube with water and air, dried, and replaced. This is when discovered it whistled when blew air thru it.6. Emperical Tests * 07_purge_00pct.jpg: 0% evap purge at engine startup while engine is cold. No sound coming from canister vent tube. * 08_purge_34pct.jpg: purge valve began to open as engine began to warm at idle. No sound coming from canister vent tube * drive for about 15 miles: no pics while driving but Evap purge ranged from 0% to 99% range. Evap PSI was always 0. * 09_purge_48pct.jpg: no sound coming from canister vent at idle after returning from drive. * 10_purge_99pct.jpg: ** purge valve wide open and canister vent tube is whistling ** gas cap is also making noise. Pushed down on it and quieted some but if put ear next to cap could hear what sounds like slight sucking sound. * Gas cap venting ** the gas cap does appear to be vented but only one way - allows air in at certain pressure levels but not out. ** found several internet references but nothing concrete on this specific gas cap - here's one reference *** Fuel caps have not been fully vented since the 1960's. Modern fuel caps typically have valves that relieve positive and/or negative pressure once it reaches a certain level.7. Other observations * no codes present on UltraGauge * UG Evp PSI never went above 0. ** My understanding is PSI would be below 1 so perhaps UG gauge could not measure though it does include decimals in the gauge? ** Could be FTPS is not present? ** Could be FTPS is present but calibrated out per 2006 MY OBD referenced in 3? ** Could be FTPS is present but only monitored during emission test which are only run during certain conditions? ** Will continue to monitor since I obviously don't know and could not verify one way or the other * Gas cap light off never came on ** O6 MB does have gas cap off light but it never came on - even if started or idled with gas cap off ** 06 owners manual references OBD II emissions monitors and the gas cap off light being one. This is generic documentation for all 06 Econolines regardless of OBD emission certification so probably covers it in case vehicle supports it.Rich 2 Likes
Re: Vapor Canister Venting Noise Reply #3 – September 03, 2018, 05:55:11 pm RichGot to give you credit for effort, don't think I've ever seen a more detailed analysis than yours. If I were still writing performance reports yours would be at the head of the list. You deserve a good answer! 1 Likes
Re: Vapor Canister Venting Noise Reply #4 – September 04, 2018, 10:42:31 am Quote from: Lazy Bones - September 03, 2018, 05:55:11 pmGot to give you credit for effort ...Thanks - just wanted to know the cause of the sound and turned out I took the long way to get there. It helps me to understand what I've read if write it down so thought I might as well post it.Rich 1 Likes
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