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Discussion Starter · #1 ·
I have a 2011 Silverado 5.3 liter, and have a check engine light on due to a PO442-small EVAP leak. I have replaced the EVAP vent control solenoid, and the purge valve. I purchased a smoke machine, used that tonight and cannot see any leaks in the system. The only place it was showing smoke was the line coming from the EVAP vent valve solenoid to the fuel filler cap, I believe that is normal considering the truck is off, and the EVAP vent valve shuts when the truck checks its system correct? As I said that vent valve is brand new lines and all. I disconnected that line on the charcoal canister and checked the system. There was no smoke coming from anywhere that I saw, and I tried smoking it multiple times to be sure. So my question is where to go from here. Is it the charcoal canister? The fuel tank pressure sensor? In the system those are kind of what I’m down to considering I saw no actual leaks? Just curious what anyones thoughts are who might have any with this annoying insignificant issue that keep illuminating my check engine light.
 

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How was the gas cap? Those are notorious for wearing out and not sealing correctly over time.

PS: What smoke machine did you get? I'd like to get one too.

-DallanC
 

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Discussion Starter · #3 ·
How was the gas cap? Those are notorious for wearing out and not sealing correctly over time.

PS: What smoke machine did you get? I'd like to get one too.

-DallanC
Gas cap was replaced first, it’s sealed and not leaking, no smoke visible there. I’m just at a bit of a loss considering what I’ve replaced and the fact there are no leaks. My next steps would be the charcoal canister and fuel pressure sensor, but if I have to drop the tank for that I’ll likely replace the fuel pump while I’m at it seeing as the fuel level gauge has been in and out of accuracy for a while now as well. Such an annoying, and increasingly becoming expensive little problem.

I got this one:



I couldn’t go to the $8-900 range ones but also didn’t want one of the super cheap ones either. I’ve only used it this once but it’s a good kit that comes with a lot of stuff. It worked great tonight, just didn’t see any leak.
 
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Dont drop the tank, pull the bed. I've done it 3 times now on my 05 GMC. Undo the bolts, unhook the tailight wiring, 4 ratchet straps to the garage trusses, lift it up. The fuel pump and sending unit just need the hoses unhooked and the lockring turned and it all lifts out.

-DallanC
 

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Discussion Starter · #5 ·
Dont drop the tank, pull the bed. I've done it 3 times now on my 05 GMC. Undo the bolts, unhook the tailight wiring, 4 ratchet straps to the garage trusses, lift it up. The fuel pump and sending unit just need the hoses unhooked and the lockring turned and it all lifts out.

-DallanC
I’ve considered that approach. I’ve done a 95, and 06 Silverado, but I dropped the tank in both those scenarios. Maybe I’ll give the bed approach a try this time. I was kind of honestly expecting the leakage to be around the fuel pump given the items I’ve replaced. From what I’ve read the charcoal canisters don’t go bad all that often, it is on dusty roads a lot though and there is some mention of that causing the charcoal canister to go bad. But I’m really down to a couple items at this point, the charcoal canister and the fuel pressure sensor. It’s getting to the mileage I’d almost feel better if the fuel pump was replaced anyway, I’m chest deep, at this point I may as well take the full plunge and have basically an entirely new EVAP system. If it comes on after that I’ll have to burn it. I do wonder if it’s simply the fuel cap being improperly on or something from time to time. I can clear the code and it will stay off for a good month+ before reappearing. Regardless I know the fuel level sensor is starting to go bad on the pump so it wouldn’t hurt my feelings as much as my wallet to simply change it all.
 

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Do you see any smoke on the top of the tank between the bed and cab? The hoses are all right there, you can usually see them. Also, use a cheap laser pointer as you look for smoke, the beam really lights up smoke that you might otherwise not see.

IMO, its the purge valve either stuck or leaking. Check the leads with a tester to make sure the voltage is good. Then you can run direct power to it to and you should hear a pretty audible "click", that will at least identify if its stuck or not. You can remove the line downstream from the valve, and see if any smoke is blowing past it when its closed... that will also identify a bad valve.

Those super fancy expensive diagnosis tools let you toggle the valve off and on with a click on a menu when plugged in. Looks super nice but expensive for a shade tree mechanic. LOL

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A guy in my neighbor hood had his fuel pump go bad on a 2011'ish GMC in the west desert. He hiked out until he got a cell signal and called someone to make the drive and get him. Next day they went back in with tools lifted up just the cab side of the bed with a floor jack and R&R'd the pump then drove out. He had access to a heck of a nice shop here in town to fix it but he figured what the heck, they'd just do it there vs towing the truck 80 miles back.

Some of these engine codes suck trying to track down. I was getting a LEAN BANK error only when heavy towing on hot days at high rpm. So, 3-4 times a year it would throw the code on a vacation or whatever. I'd clear it when I got home and it would stay off until the next trip. I looked over everything... eventually someone recommended cleaning the MAP sensor which I did, havent had the code since.

/shrug.


-DallanC
 

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Discussion Starter · #7 ·
Do you see any smoke on the top of the tank between the bed and cab? The hoses are all right there, you can usually see them. Also, use a cheap laser pointer as you look for smoke, the beam really lights up smoke that you might otherwise not see.

IMO, its the purge valve either stuck or leaking. Check the leads with a tester to make sure the voltage is good. Then you can run direct power to it to and you should hear a pretty audible "click", that will at least identify if its stuck or not. You can remove the line downstream from the valve, and see if any smoke is blowing past it when its closed... that will also identify a bad valve.

Those super fancy expensive diagnosis tools let you toggle the valve off and on with a click on a menu when plugged in. Looks super nice but expensive for a shade tree mechanic. LOL

------------------

A guy in my neighbor hood had his fuel pump go bad on a 2011'ish GMC in the west desert. He hiked out until he got a cell signal and called someone to make the drive and get him. Next day they went back in with tools lifted up just the cab side of the bed with a floor jack and R&R'd the pump then drove out. He had access to a heck of a nice shop here in town to fix it but he figured what the heck, they'd just do it there vs towing the truck 80 miles back.

Some of these engine codes suck trying to track down. I was getting a LEAN BANK error only when heavy towing on hot days at high rpm. So, 3-4 times a year it would throw the code on a vacation or whatever. I'd clear it when I got home and it would stay off until the next trip. I looked over everything... eventually someone recommended cleaning the MAP sensor which I did, havent had the code since.

/shrug.


-DallanC
No, there’s no smoke coming from that area at all, I can see half the fuel pump where you’re saying, and I’m pretty certain there’s nothing coming from that area. I might still give the laser a try though. The purge valve is new, but that doesn’t necessarily mean it’s good as I’ve found out a few times. I’ll have to test it. And yeah, I have a scanner tool and it can clear the code but it’s not fancy enough to open and close the valve like those popular YouTube mechanics lol.
 

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Change the tailgate to read RAM and your problems will be solved. :oops:

Wish I could help, but I don't mess with that kind of crap anymore. It's much easier to drive to a dealer or great mechanic shop and have then fix a problem. It will likely cost 4X as much, but its worth it to me.

I've had nothing but trouble with Chev and GMC trucks in the past. Except the 69-72 trucks I've had and wish I still had them.:cry:
 

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Discussion Starter · #9 ·
Change the tailgate to read RAM and your problems will be solved. :oops:

Wish I could help, but I don't mess with that kind of crap anymore. It's much easier to drive to a dealer or great mechanic shop and have then fix a problem. It will likely cost 4X as much, but its worth it to me.

I've had nothing but trouble with Chev and GMC trucks in the past. Except the 69-72 trucks I've had and wish I still had them.:cry:
Overall it’s been a good truck, the light just annoys me. And yeah I’d prefer a 73-87, but good luck to us both on those I think.
 

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I've got a 2009 Nissan Frontier that we've had similar issues with. I replaced the charcoal canister (cheap) and that fixed things, for a while. The light still comes on occassionally....but a couple days later it will turn off and stay off for a few months again...

The biggest issue is that once in a while while filling with gas the pump will click off and you can't get gas to go down the tank. At that point, we just have to fill the tank VERY slowly.
 
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Vent line is plugged somehow if its filling slowly. I have the same issue in my RV trailer, it has two fresh tanks and the first fills really fast, second alot slower so it takes some time to equalize them and get them fully filled. The Fuel tank on the same trailer is a real PITA... its a 40gal tank and I can get to 30 easy enough but beyond that I have to invert the pump handle (upside down) to trickle in more (apparently it has no vent at all).

Agreed its frustrating.

-DallanC
 

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I just fixed my daughters Jeep that had the evap code. It was the purge solenoid. Someone put it in upside down and it ended up getting stuck shut. The voltage test showed no clicking sound. I also found a loose vacuum fitting which can also make it fail. The GMCs are known for having a leaky evap vent solenoids and faulty tank pressure sensors.
 
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