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Vapor Canister Vent Solenoid: 2003 Sierra 4.8L SCSB Bed Tilt?

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Richard - It does look like rodent damage.  I have chipmunks and squirrels.  I don't have mice (that I know of).  I don't have any mice problems in the house either.  I guess I'm going to chalk it up as the truck being in service for 21 years.  And stuff just getting brittle.  I don't think chipmunks tend to nibble on stuff like that.  I see them around, I've never seen them hop out from under any of my vehicles.


The only mechanic I ever use (really smart & capable guy), says that rear nipple is part of the tank.  So I cannot replace it.  Since it is only drawing off vapors, and not pressurized with fuel, I think I'll see if I can put a short piece of fuel line on it, and use a hose clamp there.  And see if I can attach the new 3-way line to that short piece of fuel line.  I'll figure something out.

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Posted (edited)

A couple days later and I've had time to work on it.  The weather from 5:30 pm onward has been great.


I got the 3rd fuel line needed yesterday.  When I got home I got all 3 installed.  I had pulled the fuel relay and tried to crank it just to try to use all of the fuel in the lines.  There was still a shot of fuel in the return line and I got an earful of it.  :D  Better than an eyeful. 


I got all 3 lines installed last night.  I cranked the truck, on the second attemp it fired right up, checking around, there were zero leaks!


I just have to figure out how to connect to the evap nipple.  I was thinking I would hose clamp a short piece of fuel line onto the broken nipple, then run a fitting with a barb end on the other end of the fuel line, and hose clamp that as well.  The other end of the plastic fitting would have the gm style shoulder for that quick connect to latch onto.  This is just vapor, it's not running fuel, it should be ok.  Any suggestions?


3 NEW FUEL LINES (I think the corrugation on the wire harness I'm holding back may have rubbed on the line that was leaking).

3 New Fuel Lines.jpg


NEW EVAP LINE NEEDING CONNECTION (this is the only thing left then the bed goes back on).

New Evap Line not Connected.jpg


One of these barbed fittings with the shoulder (the quick connects that ship with these will be trashed), attached to a hose attached to the broken nipple.


Edited by 7milesout
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Here's my solution to the attachment to that nipple.  With that, the bed is ready to go back on, as soon as I can borrow the manpower.  And I think I want to try to find a way to hold that corrugate-covered wire harness off the fuel lines.



Evap No Leak.jpg

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Just so you know for next time tilt the bed from the the cab to back next time. You remove all the bolts except for the last 2 by the bumper just loosen them and tilt it up like a dump truck. I did my fuel pump this way very easy and plenty of room.




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Will try.  But I'm built like Shrek.  I may not fit in there as well as you!  :D


Taking the bed off is actually quite easy ... depending on manpower.

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  • 4 weeks later...

One last follow-up on this issue.  It wasn't until this morning that I checked and the emissions system finally showed that everything was READY.  Up until this morning, the "Evap System" remained in a NOT READY state.  Which had me worried that maybe there was another leak hiding somewhere.  When I was getting the Evap Large Leak DTC & Check Engine Light, it would show in the emissions system check the same thing, "Evap System" was always NOT READY.


But it finally got READY.  I guess it took a tank capacity cycle.  Meaning, I've read that in order to qualify the Evap System as ready the tank has to be somewhere between 25% full and 75% full (something like that), so that there is air above the fuel.  It must be a little more complex than that.  Soon as I put the bed back on, I filled the tank (without thinking).  I ran it down to about 15%, then filled it again.  And now it has ran down about 5 or 6 gallons and is now finally READY.  It had me worried.


All is well.  The truck is running good (has always ran good), no CEL, no fuel leaks, drop shackles installed, all is well.  I will mention, it knocked out 16.9 mpg on that tank, which was better than I expected, even above average.  Maybe it had been slowly leaking for a while before it finally completely let loose.

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