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Username Post: Adventures with P0442 / P0455 small / gross evap leak        (Topic#348345)
Posts: 28537
Age: 47
Loc: Texas
Reg: 08-01-03
11-22-17 01:25 PM - Post#2715353    

Patient is a 2006 Silverado SS - Intimidator edition, about 90K miles on it. A little while back began getting the TIGHTEN FUEL CAP error on the driver display. Code check showed P0442 small evap leak; further driving resulted in P0455 gross evap leak. Began having trouble filling the tank as the pump would constantly click off even at the slowest setting.

When it was just P0442 first hope was just needing a gas cap, since the one I had was an aftermarket locking cap with a very cracked O-ring seal. Installed new AC Delco # GT225 (GM # 15763225) a little different from original, doesn't have a "line" style tether on it but surround-style, but it's OEM and works fine. Cleared code and it came back, not really a surprise.

Next up, ordered AC Delco # 214-2082 (GM # 19207763) revised canister purge valve assembly. There are 2 different part #'s depending on your year model of GMT800 truck so look it up before ordering. This is the revision where the filter is separate so it can be remote mounted.

Old purge valve/filter assembly removed. Take care removing the clip from the white plastic connector to the canister; fingernail or a small screwdriver to gently push the tabs loose and slide the clip out - you're re-using the white plastic piece, which requires carefully cutting the plastic hose off with a utility knife, small side cutters, etc. I also used needle nose to help peel the hose off.

Purchased 12' of 1/2" hose, need about 16" of it to attach new purge valve to the canister, the rest of it to remote mount the filter towards the front of the truck. This is enough for my 2006 extended cab with purge valve at rear of tank and my chosen place to mount the filter by the transmission; measure your own installation to be sure.

New purge valve in place and connected, and found it easier to feed the hose from the large hole in the frame ahead of the tank and push towards the rear, then route the rest along the frame above the fuel line clamps and ABS module bracket.

Mounted remote filter above transmission tailshaft housing, zip-tied to the transmission vent hose, not too tight so the hose doesn't get pinched.

Cleared codes using Torque Pro, BAFX Products bluetooth OBD2 adapter, and my trusty BlackBerry Passport SE.

Post-mortem on the old filter showed a little bit of dust, not a ton of it, so I'm hoping my canister is still good. Some driving when I return to work Friday should show whether the codes come back, if they do, I'll do the canister next.


06 Silverado ISS / 06 Silverado SS / 06 300C SRT8

Valued Contributor
Posts: 2544
Age: 44
Loc: West Michigan
Reg: 02-18-12
11-22-17 08:41 PM - Post#2715404    
    In response to someotherguy

At my old job, we had a van that wouldn't take gas, like that. We had it fixed, but it was never really quite right. I think everything was replaced. I saw a TSB, or it mentioned online, that GM was blaming spider webs?

I think the last time it was "fixed" it was just left open and/or bypassed in some way. Under the truck/van is a stupid place, for GM, to put that stuff, in my opinion.

99 K3500 RCLB

Edited by 454cid on 11-22-17 08:41 PM. Reason for edit: No reason given.

Posts: 28537
Age: 47
Loc: Texas
Reg: 08-01-03
11-23-17 09:49 AM - Post#2715465    
    In response to 454cid

Dunno about the vans and spider webs! But the GMT800 trucks are also known for the evap canister getting damaged by ingesting too much dust through the original design purge valve. I can see how it would happen; the valve is placed badly back there near the rear wheels, and the filter inside it is near worthless. It's just a simple ring of very coarse foam that lets really large particles through. The new remote mount filter has a layer of that coarse foam, and underneath that a layer of much finer foam. That and the better placement should solve the issue. I'm banking on my canister still being good since the valve didn't give up too much dust when I took it apart.


06 Silverado ISS / 06 Silverado SS / 06 300C SRT8

"5th Year" Gold Supporting Member
Posts: 2327
Age: 31
Loc: Utica ny
Reg: 04-13-10
11-23-17 07:34 PM - Post#2715524    
    In response to someotherguy

Seems to be about money.
What about the fuel control module?
that is located between the spare tire and rear bumper... and the vent is on the top.
Leaves you sitting in a heartbeat thinking your fuel pump is bad. But no it is that module that most didnt know existed. same with the rear lamp module. Same place. Maybe these trucks werent built for NY.
I like my 90. No emissions worries there

Old School GM fan FOREVER

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