Changed entire evap system, but can't blow out line from engine bay

[Bama704]

I have an 05 Tahoe, and had the engine light on, P0455.

So I changed all things that went with the evap system. Charcoal vapor canister, vapor canister vent solenoid, & vapor canister purge valve.

I can not fully blow out the line going from the tank to the purge valve. With the lines fully open (disconnected on both ends) I blew compressed air from the tank side to the engine bay side and vice versa, however I can still hear the charcoal pellets in the line. Any tips on how to get them all out?

 

[TollKeeper]

If you are positive that the lines are fully disconnected, and no valves, or electrical connectors, are present in the line, I have seen people using water, then once cleared, compressed air to dry the line out.

Its likely not charcoal pellets, but dirt/mud/rocks.

Could also remove the line completely, lots of work, and hang it vertical, while blowing air thru it.

 

[OR VietVet]

I gotta ask, why did you replace all those components and not replace the lines. I did all that on my 05 and the two lines were $19.99 and $107.79 at RA.

 

[Joseph Garcia]

I don't know what the diameter of that hose is, but would it be possible to insert an electrical wire, say a 16 gauge insulated wire, into the hose and feed it through, as far as it will go, and 'push' the obstruction out?

 

[TollKeeper]

.. Or a coat hanger

 

[iamdub]

I have an 05 Tahoe, and had the engine light on, P0455.

So I changed all things that went with the evap system. Charcoal vapor canister, vapor canister vent solenoid, & vapor canister purge valve.

I can not fully blow out the line going from the tank to the purge valve. With the lines fully open (disconnected on both ends) I blew compressed air from the tank side to the engine bay side and vice versa, however I can still hear the charcoal pellets in the line. Any tips on how to get them all out?

When I did this on my '08, I messed up by trying to shotgun the pellets out of the line with 150+psi. That just made them compact together in the bends of the lines, forming clogs. There are loose pellets between these clogs and that's what you hear rattling. I had to beat, shake and flex the lines near the bends to work the compacted pellets loose, kinda like those glow sticks you bend to crack and make them glow. I then used light puffs of air to gently move them through and out of the lines. When I had the tank dropped, I removed the hard lines from that and whipped them all around while beating them against the concrete to knock the pellets loose. Afterward, I could go full throttle with my blow gun into the line.

I never thought about trying to dissolve them with water. I'd be interested to see if they'll dissolve. Can you get some that you've already gotten out, like from the EVAP canister, and soak them in a cup or something?

 

[Bama704]

Sometimes it's easy to make things difficult.
I just ordered a new line. Will be here on Friday and will change it out. Thanks.

 

[OR VietVet]

Did you order both or just the one?

 

[Fless]

Another thing to try is using stiff weed whacker line to push through. If I were to need to do this, I would start from the canister end, since that's probably where most of the charcoal is, and push it back up the line a little to see if I could loosen it up. Then the method that @iamdub mentioned, with short puffs of low pressure air from the engine end while vibrating the line.

 

[blueinkd]

Glad I didn't have this issue when I did mine. May I asked what you are using to blow these things out. A proper blow gun with the correct blow tip at the nozzle will ensure maximum air delivery. Your regular metal tipped nozzle won't deliver the same air volume/pressure. Considering the length of the lines I had to use a different tip on my blow gun.

 

[Fless]

Glad I didn't have this issue when I did mine. May I asked what you are using to blow these things out. A proper blow gun with the correct blow tip at the nozzle will ensure maximum air delivery. Your regular metal tipped nozzle won't deliver the same air volume/pressure. Considering the length of the lines I had to use a different tip on my blow gun.

And it can be difficult to get a sealed connection on the purge valve hose connector for the air compressor tip. I've used a short piece of fuel line to stick in the connector to get a good seal. If the fuel line is a little too small to seal at the inside o-ring, a few wraps of electrical tape can make it just the right size to fit the blow tip.

 

[iamdub]

Sometimes it's easy to make things difficult.
I just ordered a new line. Will be here on Friday and will change it out. Thanks.

So true. Blasting it with high pressure was the redneck power monger method that seemed cool. I was quickly corrected and a little ashamed once I realized I did it to myself.

 

[iamdub]

Glad I didn't have this issue when I did mine. May I asked what you are using to blow these things out. A proper blow gun with the correct blow tip at the nozzle will ensure maximum air delivery. Your regular metal tipped nozzle won't deliver the same air volume/pressure. Considering the length of the lines I had to use a different tip on my blow gun.

I used a standard blow gun with a rubber cone tip- the type that comes with most any air tool variety pack. My compressor is a 60-gallon with 11.9 CFM @ 90 psi, hose is a 3/8 with high flow fittings so they flow considerably more than the 1/4" fittings. I pressed it into the QD fitting from the engine side and let 'er rip. Jenn was under the Tahoe holding the other end, aiming it out the shop. It let out a loud hiss that lasted about .0001 second with a short blast of pellets, then barely had any flow. I immediately knew what had happened so I blasted it from the tank end to try to reverse what I had done then started my beating, flexing and hammering with gentle puffs from both ends until I didn't hear anything else moving in the line.

You don't need "maximum air delivery" to move the pellets out. The pellets can make their way all the way to the purge valve on the manifold, which includes a vertical climb of at least 12", with just the engine vacuum. I guess if your lines don't have a whole lot in them, then you could get away with shotgunning it. Mine was full.

 

[blueinkd]

I used a standard blow gun with a rubber cone tip- the type that comes with most any air tool variety pack. My compressor is a 60-gallon with 11.9 CFM @ 90 psi, hose is a 3/8 with high flow fittings so they flow considerably more than the 1/4" fittings. I pressed it into the QD fitting from the engine side and let 'er rip. Jenn was under the Tahoe holding the other end, aiming it out the shop. It let out a loud hiss that lasted about .0001 second with a short blast of pellets, then barely had any flow. I immediately knew what had happened so I blasted it from the tank end to try to reverse what I had done then started my beating, flexing and hammering with gentle puffs from both ends until I didn't hear anything else moving in the line.

You don't need "maximum air delivery" to move the pellets out. The pellets can make their way all the way to the purge valve on the manifold, which includes a vertical climb of at least 12", with just the engine vacuum. I guess if your lines don't have a whole lot in them, then you could get away with shotgunning it. Mine was full.

Cool. Sounds like you had it under control. Just checking. I'm surprised how the line clogged up like that. Mine had charcoal pellets in it but was clean with minimal effort. I did dropped the tank and blow out the assembly of hoses on top of the tack.

 

[91RS]

If the canister came apart on the vent side you’re also going to need to drop the tank and clean out all the pipes on top of the tank and remove the fuel pump and clean all the charcoal out of the tank and the vent pipes inside the tank. I just had this happen to my 08 and then had three customers have this same problem after never seeing it in my career. It’s a royal PITA. I ended up using bulk nylon fuel line taped to a shop vac to clean out the pipes in the tank.

 

[iamdub]

Cool. Sounds like you had it under control. Just checking. I'm surprised how the line clogged up like that. Mine had charcoal pellets in it but was clean with minimal effort. I did dropped the tank and blow out the assembly of hoses on top of the tack.

There's no telling for how long mine had been ruptured. It's a weekend ride with relatively minimal drive time even then, so it could've been slowly packing the lines full over a long period of time. I used to have a habit of topping off- no more!

Was pretty full all the way to the purge valve: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1509160

 

[Bama704]

Thanks for the reading guys.

I ordered both lines and followed the same redneck method as @iamdub

 

[George B]

Just thinking but… now about using a shop vac connected to the line to suck the pellets out?

 

[mountie]

I had everything replaced on my '05 Yukon a little over a year ago.... But.. I still get that " Tighten Fuel Cap" warning. I replaced the cap with a GM cap... No change. I wonder if my lines are still a problem. How long are the 2 lines and is it difficult to just replace?
( I will confirm my lines were cleaned by my mechanic,,,,, and how..... If he did it with success?

 

[91RS]

HThis is my 08. I was getting tighten gas cap and couldn’t fill with fuel. Replaced the canister, vent valve, and thought I had the lines cleared out. Still have tighten gas cap message. Took the tank completely out today and the big line inside the tank is full, there’s a ton all inside the tank (and it’s been in there at least a month and the fuel hasn’t dissolved it so don’t hold out hope for that), and the purge line on the tank is completely clogged which is the tighten gas cap message. I haven’t gotten to seeing if the pipe on the truck is also clogged.