fuel filling problems

[dla442]

I am shooting on alimb here, but given the good knowledge base here at GMT i am compelled to ask a question not about my trailblazer! Have an 05 impala(still with gm here lol) and the gas tank is a bitch to fill, handle clicks off tons of times. I replaced the fuel vent solenoid, still a bitch to fill. The car was just purchased for my mother. no MIL lights from a full tank to a 1/4 tank. Evap monitor shows no hiccups. Dont want to start replacing canister, purge valve, tank pressure regulator without some advice. Was thinking of checking hose from purge solenoid to canister for a plug. But i suspect it is not since i blew and sucked(dont say it) on the tube and watch the gas tank pressurize and depressurize(expand and retract). Looking for some good knowlege on this stuff before I spend $$$ tackling a problem that I do not know where to start at except for the vent solenoid, which btw was clean and not plugged so only 20 bucks wasted.

thank you guys much

 

[The_Roadie]

If I understand the system correctly, the vent and purge solenoids are there to just make sure the tank stays pressurized enough to make vapors flow through the charcoal canister so they can condense and be recaptured instead of venting to the atmosphere. While you're running. When the ignition's off, all solenoids close to make sure nothing vents.

Filling the tank uses a vapor recovery nozzle on the pump hose (in CA and most other states, I thought) and clicking off early is a flow rate problem through the fill pipe/hose. Nothing to do with solenoids or the EVAP system.

I know people will gleefully correct me if I'm wrong, and I'm waiting to be educated.

 

[C-ya]

Maybe something is clogging the fill hose? Try disconnecting the hose from underneath and see if it looks normal. It may require dropping the tank a bit/all the way. It should have an anti-siphon device in there that may have some crud (<--technical term) in it.

 

[RayVoy]

I think it is a problem with the nozzle on the hose as well. It trips off from back pressure (the nozzle thinking the tank is full). And, I know, the design of some tanks appears to trip it earlier than others.

My fav fill station has 8 pumps, 2 are impossible to use, 4 trip a lot and 2 hardly ever trip.

I think the best advise is to try other nozzles.

 

[Mark20]

I have a similar problem on the Voy with certain pumps. I have to position the nozzle just right if I want to use the full flow setting.

 

[dla442]

yup, been to different stations and pumps...same reult. From what I can figure, as the tank fills in with rushing gas, the vapors acumulate and the vent solenoid is shut allowing the in comming air/fumes to vent out to prevent the gas pump handle from tripping off. the station pimps are definitly ruled out as the root of the evil problem. I will inspect the filler neck as well

 

[BRomanJr]

If I understand the system correctly, the vent and purge solenoids are there to just make sure the tank stays pressurized enough to make vapors flow through the charcoal canister so they can condense and be recaptured instead of venting to the atmosphere. While you're running. When the ignition's off, all solenoids close to make sure nothing vents.

Filling the tank uses a vapor recovery nozzle on the pump hose (in CA and most other states, I thought) and clicking off early is a flow rate problem through the fill pipe/hose. Nothing to do with solenoids or the EVAP system.

I know people will gleefully correct me if I'm wrong, and I'm waiting to be educated.

The way I understand the system is that the Purge Solenoid is N/C and the Vent Solenoid is N/O.

Any expansion or contraction in the tank is routed through the Charcoal Canister to trap the fuel vapors, but air is allowed in and out through the Vent Solenoid when the vehicle is turned off..

Also found this very informative article on another Forum and have copied the link below.

The Evap System - Gas Engine Modification - GM-Trucks.com

Since the OP has replaced the Vent Solenoid, It's probably time to check for blockages in the rest of the Vent piping and Charcoal Canister.
The article suggests removing the pipe from tank to Vent Solenoid ONLY AS A TEST while filling the tank and see if situation improves. And cautions not to re-fuel with engine running or key on.

 

[Jkust]

I hate when this happens. For me it is a couple pumps at the Sams Club station that I have to avoid. I'd curious as to what is causing this for u.

 

[dla442]

thank you, i had read an article on the evap systems as well and do not have a tech-2. I have a low end code reader that actually gives live data and conducts what it calls emissions module testing. With blowing into the vent valve tube going to the canister, i can see the gas tank pressurize and releae pressure. I am just going to have to go step by step since I have no MIL light. thanxs guys

 

[Sparky]

Check your filler neck if you can. My Trailblazer had a kink in the hose where it attaches to the fill neck, disrupting the flow and making it difficult to fill at times (especially faster pumps). I was going to straighten it oub but I ended up replacing it with another (used) one when the filler neck started leaking from rust and it has been perfect since.