Typerod

Ok, so only a few weeks ago, I had a post about my alternator going bad and replacing it, also had the oil pan gasket replaced due to oil leak...now I have another issue..

2007 Tahoe, LTZ, Flex fuel, ~265K miles.

About last summer I have been having an issue with the Fuel level gauge dancing around, while I'm idle and parked, it can also dance around while I'm driving, only seemed to do it in the hot weather, but it even does it during the cold weather. Since the fuel pump is just fine, I decide to just live with that issue, until absolutely needing to drop the fuel tank for another issue or to replace the fuel pump.

So for the most part, the fuel level gauge works. But there was an instance a few weeks ago where it wasnt working, and my wife forgot to reset the tripometer and reset the fuel used gauges. So when I jumped in the car to move it, I see ohh the fuel level is low, let me be a good husband and fill it up for her. So I head to the gas station, starting filling it up, I'm thinking its near empty, but actually its not empty, its near full.

So the pump stops, I'm like thats too fast, its not full, I keep pumping a few more times and the pump keeps stopping, I keep pumping letting it stop. Then I'm like hmm, maybe its really full although the fuel gauge says it was less than 1/4 full. So no biggie, I drive away thinking my wife filled it up, but forgot to reset the gauges.

Fast forward to yesterday, my wife calls and says, the gas pump keep stopping on her. So I told to fill it up as much as she can, the tank was for sure near empty. I told her sometimes its the gas pump, but in my mind I'm praying its not a venting issue. So we run an errand last night, I stopped at a diff. station to experience the problem.

And if I run the pump as fast as it will go, it takes 15 seconds before I start to hear the gas gurgling back up to the fuel filler then the pump stops. I keep testing this theory out and it holds true. I also just set the pump on the slowest it will pump w/o me having to hold the lever, and it will accept gas but it takes a maybe 30 seconds for the pump to stop even though the tank is not full.

About 6-7 years ago I had the P0449 code and replace the evap solenoid and canister. I also do NOT have any CEL right now. My next thought is I may have just pushed the vapor canister past its limit with that gas fill I did where I thought the tank was empty but it wasnt and i kept topping off.

I'm thinking to replace the vapor canister and try to somehow vacuum out the vent lines, to see if any carbon has come out of the vapor canister and has clogged up or is starting to clog up the lines. I read somewhere this guy tried that and was successful, he did not have the know how to drop the tank, nor do I.

I would like to hear thoughts and suggestions. I also heard that there is a "roll-over" sensor somewhere in the tank that may cause this issue as well.

I think I'm in for an expensive repair in the near future....

Cusser

Pump the gas in slower.

Issues with fuel tank senders seem to be pretty common, like in my 2005 Yukon; apparently many like to blame gasoline that contains ethanol. We use the trip odometer there as well, don't trust the fuel gauge too much. Too bad GM didn't engineer-in a cover for the fuel tank area, to allow access under the second seat driver side...guess there's too much money in fuel pump and sender repairs. Most mechanics will change out the entire unit. I'm wary of paying a lot for that privilege on ours and then having the new fuel pump give out.

tech2

you are on the right track. When fueling, the gas pump shuts off from pressure build up in the tank. The vent path is most likely plugged. the test is pretty simple. go to the evap cannister...one large evap hose will go to the tank....usually the cannister has a molded imprint of a gas pump on the cannister to signify this is the vent line to the tank. remove the vent line. blow thru the line to the tank...cap off the tank....then blow thru the cannister to locate the restriction... if its on the cannister side....remove the cannister filter and blow again....the filters fill with dirt and need periodic replacement. Gm has a relocation kit to move the filter location from the filler neck to on top of the trans bell housing.
Don't jimmy rig it...have had customers do that....It will effect another evap monitor and set a code for something else.

Typerod

Thanks for the reply tech2! I just need a few clarifications...when you say "go the the evap cannister", do you mean the vapor canister, what I mean by vapor canister is the box with the carbon/charcoal in it?
I am familiar with that "gas pump" symbol from recently watching youtube vids on how to change out the vapor canister.
I am familiar with that "gas pump" symbol from recently watching youtube vids on how to change out the vapor canister.

So let me reword what I think you are saying, since I will try to tackle this tomorow...

Remove the vent line (attached to the port with gas pump symbol) which is attached to the vapor canister (carbon box), then blow compressed air into the line i just disconnected (with the gas cap off ), which will blow air back towards the fuel filler neck (i think), then blow air through the carbon box using the port with the gas pump symbol. Then just find the restriction which will either be the vent line itself, or the carbon box.

If you could pls let me know if I have understood your directions.

I'm hoping that no carbon/charcoal is coming out from the vapor canister, and that just replacing the vapor canister(carbon box) will be my true and final fix for this is.

Thanks again!

Typerod

Pumping gas slower is just a band aid, I believe. Since this is my wife's daily driver, I need to keep it in reliable running condition. Its a pain in the butt, to have the gas pump stop constantly when trying to fill nearly more than 22-23 gallons of fuel in the tank, lol.

tech2

you got it but don't use compressed air ...unless its 6psi or less....I use my lungs...if its restricted...you'll feel it.....you won't be able to blow thru it.

Typerod

Thank you sir! I finished the work a few hours ago, before I had a change to read this reply. I did use compressed air, but my air compressor isn't very powerful, its a tiny little guy, I think 1.5 gallons? But when I did blow air through the line, I could hear a delayed whistling noise, not sure if thats normal or not?

So here is an update. Received the part yesterday. Got started on it this morning about 745 or so. I put the rear wheels up on ramps in hopes to give me enough space. Got under the car, located the vapor canister. I was able to get the vent line off, not much effort, I got the line for the vent solenoid off with no effort, BUT the line that runs from the vapor cansister to the engine, which has the blue plastic tab on it, was a PITA!!

I tried getting at the blue connector but its a tight fit and I wasn't able to squeeze both sides down to release the tab locks. I kept fighting with it and fighting with it. Then I decided to drop the spare tire to hopefully get more access, then I could not get the spare tire lock to open! I put the key in the lock and tried turning clockwise and nothing the key would not budge clockwise, I tried tapping the key lightly with a rubber mallet bc it seems the key would not push in far enough. But that still didn't work. Then I just just got white lithium grease and gave a squirt into the lock, let it sit a few minutes, and that did the trick. I got the lock open dropped the spare wheel. It gave me a bit more room to work, but ultimately I had to under the car from the passensgers side and remove the two bolts holding the vapor canister bracket to the frame of the car, and then let the canister just hang while I attempted the blue locking tab for another hour or so. My goodness, I was panicking and getting anxiety b/c I felt like there was no hope of me getting this last line removed w/o breaking something which would cost me more money in the end.

I prayed and prayed and asked God for help on this one, and eventually the line came free from the canister, with no damage to anything, but I did kink the line a bit, but I didn't care much about that, at this point, lol. The kink wasn't too bad and the line is still intact, no breaks in it.

So I get the bad canister out, Thankfully no carbon/charcoal was dropping out from it, so that made me feel better that the lines weren't clogged with the carbon, like a saw in a video on youtube. I got my air compressor out and blew air into the vent line towards the fuel neck filler, and it seems clear, although I did hear a delayed whistle after blowing a burst of air through the line, still not sure if thats normal. I looked down one of the ports on the bad canister and saw some oily like substance down in there, I blew compressed air and nothing blew out that I can tell, but the tip of my air tool had this brown sauce on it from the bad canister.

So anyway, go the new canister bolted onto the bracket, then the bracket bolted to the car, then clicked on all 3 air lines again. Buttoned up everything. Started the car, no CEL's, so now off to the gas station for the real test.

Got to costco, I saw the "fuel used" gauge was at 8.8 gallons, so I got the pump started and just let it pump full speed, while i was holding the lever down. After about 5-7 secs I thought I was hearing the fuel gurgle back up the filler neck, and some anxiety crept back over me, but maybe I was just being paranoid, the pump stopped once, and that was after I had pumped 9.02 gallons into the tank. It seems to be operating as intended now! All in all, it took me about 3.5 hours and just about a third of that time was me trying to release the tabs on the blue connector. If I had a lift, I'm sure I wouldve been done sooner, lol. Its tough to work on my back, and have to fight my vertigo, while do this repair, lol.

I will monitor it and report back with one last update in a few weeks. But I think this one is resolved now! *fingers crossed*

But a big Thank you to God Almighty for allowing me to do this repair properly and save money! And also a Thank you to tech2, you are truly a great help to many of us on this forum!

When will TypeRod's Tahoe have another problem post here on Chevroletforum? Stay tuned in until next time, boys and girls! lol!

tech2

good job.
replace that cannister filter...its protects your new cannister from clogging up with dirt.

Typerod

Thank you sir! Should I really consider replacing the evap canister too? I replaced that evap canister and solenoid maybe 6-7 years ago...I don't have an CEL. I guess I should feel blessed that the vapor canister is the original one that came in the car from the factory, and I got ~264K miles out of it.

tech2

nope, if the cannister is not plugged leave it...its expensive...the filter is cheap.