Bleeping QD lines to evap / fuel system

I took apart the Vent hose. VERY easy with a heat gun. I'm trying to spec out quick connect fittings though. I notice if I buy on eBay they are literally a fraction the cost of parts store doorman.

I think the vent hose is a 5/8" SAE right angle QC. Not exactly sure if I spec right though? Anybody know??

DETAILS:

Male (hose side) 16mm OD 90degree to Female (canister side) 16mm ID

I think these are the size? https://www.ebay.com/itm/174221824731

Ah hell... I went to reinstall everything and despite thinking I glued that nipple on well it broke off again. I also filled my tank up with gas and got the WORST mileage since I bought the truck (I've logged every tank) just under 12MPG.

I'm not sure what's up. Super annoying. After I filled it up I felt the tank around sending unit, nothing. Nothing around evaporative lines or canister either. No engine codes and no gas smell. No clue why I'm getting such horrific mileage. But it does have a gas smell sometimes.

Following.

I too had to replace my charcoal canistet because of that #$%m nipple breaking off. I swear everything I touch on this truck that's plastic just crumbles in my hands. I'm convinced she was left sitting somewhere in the desert to bake in the sun for a couple years unprotected. Gotta love AZ. I digress though...

Have you checked out the fuel filler hose? I have this issue where when I'm filling the tank the smell of gas is horrendous, it's as if I'm pumping it straight onto the ground. I haven't looked into it too much yet but I feel like the filler tube/cap base flap assembly is to blame. Sometimes gas will even leak out onto the gas cap area. Once in s great while ill smell gss while driving, but almost akways smell it upon startup...

How's your fuel pressure regulator? If you pull the vacuum line off of it and smell it and if it smells like gas it needs replacing as gas shouldn't be crossing the diaphragm. If the vacuum line has a leak, or the fitting is cracked, it could be letting out the gas smell. That was at least part of the problem on mine. When I first touched them t'o check them, they all crumbled in my hand. I used a small section of ¼ pcv hose or something, I forget, it was thick like rad hoses and fit real snug over the nipples on the intake and fpr, put smaller hose over the plastc tubing that fit snug a decent length, then the larger tubing snug on to that. Sealed it up good.

Still figuring out the rest of the issue though

@Meathead16 thanks! Yeah I cry when I realize the Chassis & drivetrain on these GMT800s is KILLER awesome but the rest of the truck is a heaping pile of pure crap. It's been an uphill battle keeping from disentigrating since I bought it. However, that said, I bought mine in Rio Rico by AZ Mexico Border and guy literally parked it next to the SUN outside.

My issue is similar, I occasionally smell gas on start-up. My guess has been it's because I'm in open loop with PCM fuel controller. However, sometimes it's REALLY strong almost like I poured a tinge of gas on the ground. I don't ever smell it while driving though thank god. Sorry to hear that.

What year is your truck? Sad thing is I have a 2001 and they seem to have changed the evap canister design shortly after 2001. Long story short, the short run / evap design on my truck cost a bloody fortune to replace versus like $50 for the newer design So I really do want to fix the canister. I don't think they really go bad unless you get them wet or completely soaked with fuel.

What I've done so far:

- Evap lines, need rebuilt, all Quick Connects are busted up.

- Fuel filler - it's good, no issues. Simple ring clamp connection, easy enough to adjust / fix if necessary.

- Fuel Pump & Tank - I replaced entire fuel sending unit. When tank was down I cleaned and inspected it. Tank is a quality piece and still like new, along with all connections on top. I've since doubly inspected, by feeling top of tank and everything is in perfect order on top of tank.

- Fuel injectors - Completely took apart rail, cleaned and visual inspection (I have a built up 6.0L) I swapped with the E85 injectors I don't recall what that engine is called. One thing I never did was check fuel pressure / the regulator. I had ordered a fuel pressure gauge and company sent me the wrong thing long story... but I definately need to check fuel pressure. Otherwise, I've tuned the fuel for new build and it's spot on w/ Wideband O2 and narrowband.

- Fuel regulator - the vacuum line was broken when I did my injectors. I need to do the smell test! That's a great idea. I have since installed a new vacuum line.

- Evap canister - damn thing. I could scream, yeah the nipple (male fitting) for tank line broke clean off. I glued it back but no luck. I need to order a male fitting of that size, then cut them at a point where there's some extra before the lip for QC lock... then take a slightly larger diameter hose of some kind and just glue the two together with JB weld. I may actually reinforce all the fittings on the evap like that. Then get some quality quick disconnects. The ones from the factory, and upon further inspection, doorman is same style, are complete CRAP. If you are lucky you can get screwdriver to unlock them (QC tool doesn't fit). And the finger release design doesn't work. The lines themselves are great quality otherwise.

rockola1971 said:

Spray with wd40 to get any grit outta there and lube the oring seal. Feel on top of your tank. Is it wet with fuel? Sure you dont have a leaking fuel pump module oring seal? Or rotted out retainer for fuel pump module?

Click to expand...

Make yourself a smoke machine makes this kind of repair much easier.

Back to messing with this cheap junk fuel and evap line stuff from GM. Saga continues... I bought a new evap canister. Mine isn't doing anything, garage just smells like fumes when I park it. I assume cause carbon is spent up after 23 years.

Turns out the tank and purge fittings on my current canister are 3/8" fittings. The new canister I bought is 3/8" for tank, 1/4" for purge so new canister won't fit. I'm looking for another canister with 3/8" and 1/4" but cannot find one.

Anybody know how to change the purge line by the vapor canister? I cannot find a part number for it or anything.

Old canister 3/8" purge fitting


New canister 1/4" purge fitting

I thought maybe I could just glue some straws around the fitting to increase the OD. However, the stupid lip to catch the QD is 3/8" when old one is 7/8" so the clips won't even engage on it.

Second question, I cannot figure this one out. I took a road trip to higher altitude. It is as though the tank is not purging and or venting. Purge valve is new, tested and works. The vent is new, tested and works. The vent hose is rebuilt tested and works as well as the tank evap lines. The tank pressure sensor is tested and new (I read the reading with a scan tool). I can command purge on and off with scan tool and the tank pressure changes / registers on the pressure sensor as read by the PCM. Oh and the vapor canister flows freely.

However, the tank swells and when I take the cap off it vents out the cap. This makes no sense to me. I'd think it would vent out the vent line and or the engine / purge line would take the exess pressure?

Video of problem...

When the ignition is off, the vapors vent from the canister out through the vent valve in the rear. Either the valve isn't opening when the ignition is off, or the canister or line is plugged.

RockAuto shows several evap canisters for your '01, and all of them have three different size connections. Are you sure your new canister is the correct one for your Tahoe?

Turns out I'm "stupid". I forgot I rebuilt the purge fitting on canister. When I did that I made it larger so as to be able to glue a nipple over the top of the old one. One of the VERY few times my junkyard lute (personal junk pile) came in handy. Turns out I had another set of tank vapor lines w/ the correct QD. I just recycled that.

I also discovered in the process I'd mixed up the purge and tank evap ports. They were reversed. Not sure if that was causing fault where tank doesn't fully depressurize.

The vent valve is opening as expected. When truck is off I can literally see (when I look under truck) and hear tank venting through the vent valve. Hopefully I'll no longer be able to "see" the vapor under the truck with new purge valve. Nor smell it.

Thanks for help! I've gone bananas tinkering with this evap stuff. It's VERY poor quality fittings and lines from factory. I suppose they're "good enough" but not that fun to work with. That said I'm getting too good at it. Only took about 30 minutes to get the line off the tank and didn't even have to take the tank off

Matthew Jeschke said:

Turns out I'm "stupid". I forgot I rebuilt the purge fitting on canister. When I did that I made it larger so as to be able to glue a nipple over the top of the old one. One of the VERY few times my junkyard lute (personal junk pile) came in handy. Turns out I had another set of tank vapor lines w/ the correct QD. I just recycled that.

I also discovered in the process I'd mixed up the purge and tank evap ports. They were reversed. Not sure if that was causing fault where tank doesn't fully depressurize.

The vent valve is opening as expected. When truck is off I can literally see (when I look under truck) and hear tank venting through the vent valve. Hopefully I'll no longer be able to "see" the vapor under the truck with new purge valve. Nor smell it.

Thanks for help! I've gone bananas tinkering with this evap stuff. It's VERY poor quality fittings and lines from factory. I suppose they're "good enough" but not that fun to work with. That said I'm getting too good at it. Only took about 30 minutes to get the line off the tank and didn't even have to take the tank off

Click to expand...

I wouldn't call it "stupid," just experimenting!

Haha thanks!

Anybody know where to buy a tool that fits the test port on the evap system (under hood by fuel rail)

Also I assume the tank should hold pressure till vent or purge is opened?