Car won't take gas?
 

Alright guys, had some trouble with the TA tonight. I've had a CEL on because of an evap leak for some time now and I've filled the car up before with no issues. Tonight I was running low on gas so I stopped at a station to fill up.....only she wouldnt take a single drop, it just came spewing back out. I thought maybe this pump is junk and went down the street to another station and the same thing happened. The second you pull the trigger fuel was running down then side of the car. So now I'm twenty miles from home with barely any gas. Long story short I lugged 6th the whole way and somehow made it. I'm guessing this has something to do with the evap code I have? Any help would be greatly appreciated! Thanks!

sounds like the vent for the filler neck isnt doing its job of relieving pressure as you fill up. might have something to do with evap code as well. take a look at the filler neck under that stupid plastic guard in the wheel well. evap can is back there too. seen it before when its dryed or weak from topping off all the time. and the hose collapses.

Alright, thanks pizza I'll check it out. That's where I was gonna start too. But I have a feeling it has to do with the evap code. Well see though.

Yea I would say the evap vent valve is not functioning. Had the same issue on my silverado.

Alright, so I finally had some time to look around today to try and find out what's going on. The filler neck looks fine to me??? I snapped a couple pics. So I had a couple gallons of 93 laying around and decided to try it again. This time it took fuel no problem.....whats going on?


http://i662.photobucket.com/albums/u...125956_443.jpg

http://i662.photobucket.com/albums/u...130002_752.jpg

U have an intermittent sticking vent valve. It's common may work fine for months mine is. Had the exact same problem. Would fill my truck and the pump would either keep clicking off or burp fuel out at me. It's jut like trying to dump a bottle I water with no air hole it burps and takes forever.

The vent has nothing to do with the filler neck. Is it also throwing a p0440 code? Evap small or large leak. The will throw those too if the vale is not shutting when it's told to.

I forget what the code was. Where should the vent valve be?

Idk where exactly they r on these cars. Usually back by the gas tank. It's like the size or ur fist has probably 2 wires and a hose or 2 on it one hose may have a breather on the end or the valve has a built in breather.

Alright, thanks man, ill do some research and see what I come up with.

Seems Ill have to get to the fuel pump which means either dropping the tank......or doing the trap door. I'm not against doing the trap door but I hate to cut up a car......

Isn't the vent that white plastic piece that hangs down by the axle behind the tank? Or am I thinking of something else?

Very possible Alex. Sounds about right.

The part I'm thinking of is #10 in this picture, the diagram says "vent"

http://www.trademotion.com/media/ima.../F/FC93580.gif

there is no vent valve like your talking about Ben on these cars. its a very odd vacuum/pressure reliefe valve. on the trucks its a big black piece of shit hanging over the rear axle. this vent valve should be off the back of the tank near the rear axle. or you can also look at the hosing near the evap canister. behind that plastic cover near the filler neck. i believe this valve vents Threw the canister so no hydrocarbons are released So if the canister is plugged. no vent. it should be either white or black with 3 lines connected to it. 2 large diameter hoses and one smaller vacuum line. take a look and see. my 1993 and 1998 had them... then they were ripped off.....

Isn't that the canister purge valve that you're talking about? The little fitting with three lines right next to the canister? The tank vent is a white plastic piece near the back of the tank. Here's a pic from an LT1 car, I doubt an LS1 car is any different:

http://shbox.com/1/fuel_pump_wiring.jpg

http://www.rmsautoparts.com/prodimages/10033125.jpg

Im not seeing any hoses or an evap canister near the filler neck like your describing pizza

Thanks for the pic Alex, Ill check it out right now.

So I crawled under there and I didn't see a "fuel tank vent valve" like in Alex's picture. But if you look closely it looks like there is a spot for one but its not there. Also you'll see the end of a black plastic line that just dumps over the front of the fuel tank. I wonder if this is the line that's supposed to have the vent valve on it like in Alex's picture. I don't see how this could be causing my problem though. Any thoughts? Maybe I should try throwing a little compressed air up that line with the tank cap off? Maybe something is lodged in there?

http://i662.photobucket.com/albums/u...174202_759.jpg


http://i662.photobucket.com/albums/u...174707_283.jpg


http://i662.photobucket.com/albums/u...174739_514.jpg

And by front of the tank I mean the side facing the front of the car. I got a little confused when you guys were talking about the back of the tank.

Pizza is #3 the part your talking about? If so, its non existent on my car.

yes. plastic tanked cars suck..... ok so yeah your vent valve is part of the canister on top of the tank. might be able to get a look at it if you just lower it a bit. thats so shitty. glad i have a steel tanked car. evap can is near filler neck under plastic guard.

Ok so the evap can would be the rectangular unit next to that black hose on top of the tank? Also if that dump hose is the vent hose do you think I should just try and shoot some compressed air up it first? Or will it not do anything? I'm thinking its probably a one way valve but I could wrong.

Well I found this picture which shows what Im looking at pretty clearly.


http://i662.photobucket.com/albums/u...8/fueltank.png

I also found this little write up:

GENERAL - The Evaporative Emission (EVAP) Control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating.

When the engine is operating, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process.



MORE IN DEPTH - The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the EVAP purge solenoid valve (purge on). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned on and off several times a second .

The EVAP canister purge PWM duty cycle varies according to the operating conditions determined by the mass air flow, the fuel trim, the engine coolant temperature, and the intake air temperature. For certain EVAP tests, the diagnostic will be disabled if the TP angle increases to above 75 percent . The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring for vacuum decay.

The fuel level sensor input to the PCM is used to determine if the fuel level in the tank is correct to run the EVAP diagnostic tests. To ensure sufficient volume in the tank to begin the various diagnostic tests, the fuel level must be between 15 and 85 percent .

The PCM monitors the fuel tank pressure/vacuum level via the fuel tank pressure sensor input.

Maybe I should try replacing the evap purge solenoid valve since that's what purges the canister and its the easiest part to get to since its on the intake mani.

Damn, that's how the plastic tanks are set up? Sucks to be you. :haha: All of that stuff is within easy reach on the metal tanked cars. From that pic I'm guessing the white thing on the left is the tank vent.

Idk if it is or not, supposedly its supposed to vent into the canister and then the evap purge solenoid is supposed to purge the canister. Maybe the solenoid isn't working and the canister is fouled and can't take anymore

From what I can see in that pic and what I've seen on other gm makes the vent is the one just below the fillet tube with the red electrical plug and the one hose with the clamp. That the style vent valve I'm used to and was I. My truck. That's what vents the vapors

So your saying this is the vent?


http://i662.photobucket.com/albums/u...eltankspec.png

yeah ben is correct. thats the faulty valve. weird the steel tanked cars have a completely different setup. maybe the plastic tanks can collapse? so they added more safety measures?

Yes. That's weird the lt cars have steel tanks and don't have this style like pizza said. I'm assuming the government has something to do with it because it's so much newer. I would say like 98% sure that's ur problem.

Alright thanks man, now I gotta find out if I can get at the thing haha

I just did a bit of reading and if this ever happens to any of you guys, look under the hood of your car and follow the fuel lines and youll see a little green cap that looks and functions just like a valve stem for a tire. Use a key or screwdriver to let the pressure out and then you should be able to fill your tank. Temporary fix, but its better than being stranded like what almost happened to me haha.

Alright, I got that part out FINALLY. All I have to say is what a F$CKING C*NT it is to get at that little bastard! I really don't recommend anybody do this with the tank still up there..... its literally a C hair away from impossible. I removed the tank heat shield, had to take the three bolts that hold the panhard bar to the unibody out, lowered that out of the way, then removed the two bolts for the tank straps, then I was able to lower the front of the tank down enough to get a hand up there and feel around, still VERY tight though. Then theres a rotor spring band clamp like you see on cooling hoses clamping the hose to the unit..... good luck getting pliers on that when you cant see and can only get one hand up there at a time....that's all I have to say about that haha. The worst part is actually removing the solenoid though. But anyways there it is, hopefully the new one goes back in much easier.


http://i662.photobucket.com/albums/u...191628_945.jpg

so was it plugged?

Idk I haven't had time to test it yet, I will today after work. I'm thinking just put power to it and then try to blow through it

I tested it today, the way it works is when theres no power supply, the valve is open, I can blow air right through it no problem. When you hook it up to power it shuts and doesn't let any air escape. What I did notice though is I could hook it up to power (valve closed) and if I was blowing decently hard into it when I disconnected the power to try to open the valve, the valve would stay shut until I stopped blowing as hard and would then open. So it seems that the valve has an issue opening under heavier pressures. Believe me when I say I wasn't blowing that hard into it either, I highly doubt I can generate anywhere near as much pressure as what gets built up in the tank...... So is this thing just fagged out and cant open under pressure anymore?????

that would make sence but when removing the cap hearing hissing noise should have relieved the pressure? still doesnt mean after its been heated up/commanded closed for a length of time the valve wont stick?

When I remove the cap I don't hear any hissing or any pressure relief. What happens is the fuel cant make it past the filler neck. The neck fills up and the fuel just stays there. Its not making its way into the tank. Idk whats going on, replaced the vent valve today and the car still wont take fuel. I tried to fill it up and I could only fill up the filler neck. Brought it home, let the pressure out via the green fitting under the hood and the fuel made its way into the tank...... I had the code scanned again while I was out with the car. I have a p0440. and a p1415 which is a secondary air injection bank 1, drivers side air check valve. The p0440 code is pretty vague.

I'm confused as to why a part of the evap system would cause this issue. Isn't there a vent valve?