Can’t Fill Gas Tank

[OR VietVet]

I vote drop it. Not my money. Something needs to be replaced up there somewhere.

 

[gunslinger]

Can you blow the lines without dropping it? I was under the impression I was gonna have to drop it to do that.

 

[iamdub]

Can you blow the lines without dropping it? I was under the impression I was gonna have to drop it to do that.

There are pipes that connect to the fuel pump bulkhead at the top center of the tank. If you blow air into these pipes at teh points you can reach with the tank in place, you'll be blowing them carbon pellets IN to the pump and tank.

At 225K, if that pump hasn't been replaced within the past 100K - 150K miles, drop the tank and replace it. Then you can ensure that all the lines are clean as well as clean the out the tank. My pump worked fine beyond 200K miles but then I realized the level sensor was way inaccurate past 1/4 tank remaining. So, it pretty much can't be a loss replacing the pump while you're clearing out the pellets.

Oh- make sure the shop knows to use very little air pressure to gently blow the pellets out. They can blast 'em with full pressure to make sure they're clear after the low pressure seems to have vacated all the pellets.

 

[j91z28d1]

so what happens? the charcoal canister releases its pellets into the fuel system?

 

[iamdub]

so what happens? the charcoal canister releases its pellets into the fuel system?

That's exactly what happens. The way I describe it is they're in a permeable bag, very much like how tea is in a "filter bag". With age or abuse, the bag weakens and ruptures. I, and others seem to have concluded that overfilling the tank contributes to this. The canister is the highest point in the system as it's to catch vapors. But, when the tank is "super filled", it get under higher pressures from the fuel being sloshed around while being heated. Also, the tank being bounced around during driving gives it a primer bulb effect. Liquid fuel is pushed up through the pipes and into the canister, soaking the "tea bag" and pellets. Vapors, etc. are traveling all over the tank and up to the intake manifold, carrying the pellets. I had pellets pour out of the pipe at the purge solenoid.

 

[j91z28d1]

That's exactly what happens. The way I describe it is they're in a permeable bag, very much like how tea is in a "filter bag". With age or abuse, the bag weakens and ruptures. I, and others seem to have concluded that overfilling the tank contributes to this. The canister is the highest point in the system as it's to catch vapors. But, when the tank is "super filled", it get under higher pressures from the fuel being sloshed around while being heated. Also, the tank being bounced around during driving gives it a primer bulb effect. Liquid fuel is pushed up through the pipes and into the cannister, soaking the "tea bag" and pellets. Vapors, etc. are traveling all over the tank and up to the intake manifold, carrying the pellets. I had pellets pour out of the pipe at the purge solenoid.

I guess I should add that to list lol.

I've seen trucks at work stall because the charcoal canister gets fuel logged from fuelers topping off tanks every few days on stuff that hasn't been run. and as soon as the Purge solenoid opens, vacuum sucks in raw fuel and they stall out.

but I've not had to deal with the charcoal coming apart. ugh.

I keep adding to my lists of things to swap at some point haha.

 

[iamdub]

I guess I should add that to list lol.

I've seen trucks at work stall because the charcoal canister gets fuel logged from fuelers topping off tanks every few days on stuff that hasn't been run. and as soon as the Purge solenoid opens, vacuum sucks in raw fuel and they stall out.

but I've not had to deal with the charcoal coming apart. ugh.

Them pellets are surprisingly light. They'll ride that vacuum stream uphill and collect at the valves.

I tried shotgunning my pipes out with 150+ psi. Big mistake. The pellets, being carbon, chip off in pointed-edge fragments. So, when they're shot through a pipe and come to the first curve/restriction, they collide, wedge and compact to each other, forming a blockage. I had to take my pipes off to bend and beat their curved parts on the concrete while lightly puffing air, alternating from each direction to clean 'em out. So, use very low pressure to move 'em out, then high pressure after you're not getting any more out to make sure the lines are clear.

Definitely something to learn from others' mistakes rather than your own.

I keep adding to my lists of things to swap at some point haha.

It's always better to fix or prevent on YOUR terms.

 

[09_4WD_YUKON]

I fought this crap for the longest time. Not sure what exactly what fixed it, but had the lines blown out, changed canister and purge valve and solenoid, twice!!! lol, I do think the vibration from the 2 15s in the back helps as well!!! Good luck with, definitely a HUGE PITA!!! I was also told that the gas tank need changing as there are some non-servicable check valves in the tank that get clogged and cannot be changed, but not sure how true that is as I never changed my tank.

 

[29tomt]

Same problem on my 2003 Tahoe. My repair shop replaced entire evap system including wiring harness using GM parts and problem solved. It has been several years now. Seems I was getting a code also.

 

[opfor2]

I had the same issue on my 2011. Ended up being a clogged purge valve which is an easy part tp replace.