gas tank overflowing/car stinks of gas

[dlb]

hey all. i filled up my gas tank a few days ago, and noticed the pump shut off a few times before the tank was anywhere near full. i wasn't concerned because that happens depending on the pump, i find. so i drove about 20 kms home, everything was fine. drove it again later that day a few kms down the road and back, still fine. got in it to drive to town the next afternoon though and it really smelled of gas, so i took a walk around the car before i started it. i saw dripping coming from behind the fuel filling door (i don't what it's actually called) so i opened it and saw gas squeezing through between the filling neck of the tank and the gas cap. i loosened off the cap a bit and it started spraying fuel so i just tightened it up and left it to take the other car. the weather here has been erratic and it was around freezing the night i fueled up, and then maybe 15 degrees celsius the next day, and the car sits in direct sunlight all day so i wondered if a bad combination of a really full tank and gas vapours expanding due to the heat might cause an increase in pressure in the gas tank. also, the car gets parked on a bit of an angle, with the passenger side (and gas cap side) 4 or 5 inches lower than the driver side. would this affect it?

another possibly relevant note: last summer there was an incident while fueling up where the gas pump did not shut off and overflowed gas everywhere. i wonder if there's some fault in the filling neck of the fuel tank.

my gas cap is a cheap replacement one from lordco so i swapped it for the gas cap from my parts tercel, but it still smells like gas so i don't think it's going to be such a simple fix. dang.

thanks in advance for your help,
david

[Petros]

My daughter's CRX developed the same problem, it is your fuel tank ventilation system (the charcoal canister device). the Factory service manual has a procedure for testing each of the components (it is not difficult). Also verify the vacuum tubing is not leaking and all connected properly, and you might consider getting a new filler cap. The cap has a valve in it that is supposed to let air in but not vapors out. The all the fuel tank venting is supposed to vent through the charcoal canister to prevent fuel vapors out into the atmosphere, if something is not venting properly it will pressurize the fuel tank and cause it to burp out the filler cap. Eventually it will cause the engine to flood since the pressure with push past the float valve in the carb.

These systems are pretty reliable, so you should do okay to get replacement parts from a wrecking yard, a lot cheaper than the dealership too.

Good luck.

[dlb]

thanks petros, i searched the forum and found someone talking about the charcoal filter but didn't think it applied to mine since the leak was only at the back and there were no visible leaks under the hood. i did hear a new sound, sort of a whine, when i popped the hood though so maybe that's coming from said filter - i'll check it out in the morning. thanks again!

[takza]

One of the large hoses that goes to the charcoal canister has a tendency to fail (mine had a hole "melted" it it)...I replaced it with the right sized fuel line (don't use vac or heater hose!)...it's been doing fine since...the other one is OEM. Really had a gas stink under the hood before it was fixed.

There is a check valve in the charcoal canister that is supposed to relieve built up tank pressure....could be defective? Could try taking it out and spraying a bit of WD40 in the holes to loosen up the check valves?...or replace the canister with a used one?

You should PLAN to drive the car for 10-20 miles AFTER you refill...so there is more air space in the tank. If you have the vapor recovery pump nozzles in your area...they can be a real problem as far as shutting off early. Even with the regular nozzles there is no point in trying to top up with these cars. If you refill outside of a large metro area you can find the regular nozzles?

Here in Tibet...there is a sign on the pump saying that you have the responsibility of watching the pump...if it overflows.

* Sometimes cop wanna-be *ssholes will cause the pump to not shut off...spilling gas on the ground. Now and then the nozzle will malfunction.

* Sometimes cop wanna-be *ssholes will cause the pump to run slow.

* Cop wanna-be *ssholes like to play cheap and stupid games...just because that's who they are.

[dlb]

this will be embarrassing and clearly illustrate my lack of mechanical knowledge and experience, but the info might be useful to someone with a similar lack of skills so i'm going to post what was up anyway.

so i looked at the diagrams in the manual to find the charcoal canister. i looked under my hood, and thought i saw it, but it wasn't quite the right spot. i stared at the engine for about a day before i realized that when my friend put the weber carb in my terc, he disconnected and removed anything that didn't seem essential--namely all the emissions stuff. along with all that went the charcoal canister! so it wasn't that. i remembered i had blocked all possible vacuum leaks with those little black plugs about a month ago though, so i unplugged the metal line that use to go to the charcoal canister. it let out a big hiss, i got pretty high on gas fumes for about a minute, and that was it. it took a few days but the gas smell eventually dissipated from inside my car. i didn't like the idea of gas fumes just spilling into my engine compartment from that line though so i got a vacuum hose and hooked it up to a port on the passenger side of the weber, not really having any idea if that was a good idea or not. that was several weeks ago and the car smells normal (just my usual musky personal odour) and is running fine. ta da!

if hooking that line up to the carb was a disastrous idea, would someone let me know? it makes sense to me for it to go there, as the fumes are meant to eventually get to the carb (after passing through the charcoal canister) but one guy i talked to said i needed the charcoal canister to vent the fumes or something - no idea what he's talking about and he didn't have time to explain it to me so if anyone has any input that'd be rad.

thanks!

[ARCHINSTL]

Thanks for the confession - inevitably it will help someone.
As to drawing fuel fumes through a vacuum cleaner...unless it's air-powered, this would be a bad idea.
The vac is powered by electricity and the fumes are drawn into a blower which is adjacent to the motor - which could spark. This is not as remote of an occurrence as you might think, particularly with old appliances...
I think I'd try sprinkling baking soda or a commercial product on the inside of the car to absorb (or is it adsorb?) the odor.
Tom M.

[takza]

That hose/pipe from the tank is where the fuel vapors come from that are collected in the canister until the valve switches open to allow them into the intake...but with the OEM setup...air is drawn into the bottom of the canister...allowing the gas vapor to go into the engine. The canister also has spring loaded check valves in it to maintain a certain pressure in the tank.

If you have full manifold vac directly on that line...you could collapse your gas tank...IF the vent in your gas cap gets plugged...but even if it works...you still will likely have a pretty good vacuum in the tank.

[dlb]

ha! from what my fiancee tells me it just might be ADsorb, but she's the expert so i'll have to consult her. the car smells fine now though (minus my musky personal odour), so that's not a problem.

archinstl, i'm not sure what you mean about the vacuum being powered. are you referring to the port on the weber? i don't think it's powered, only the choke is. i could be way off though. i've just got a hose going directly from the metal fuel vapor line at the firewall to the port on the weber.

takza, two questions: what's OEM stand for, and what's full manifold vac? do you mean if the exhaust was sucking it's hardest on that vapor line?

what do you guys suggest? should i reinstall the charcoal filter? if it would increase fuel economy i'd love it. the car is very good on gas now but more is better.

sorry if my questions sound dumb, i really am pretty inexperienced with all this stuff. i'm fine with oil changes, stereos, cv joints, alternators, brakes and calipers, ball joints... pretty much anything you just put in or take out, but my knowledge and understanding of the engine is extremely limited. i've read those "how to" guides for dummies and understand the jist of engines, but still am not great at problem solving. which explains a big part of why i'm on here! i'm sure i'm not the only 4wd tercel enthusiast who is an amma though so yes, i agree that my posts might be helpful to other beginners.

thanks again for your help!

[ARCHINSTL]

Did I misread your post? I thought you wrote (or implied) that you used a vacuum cleaner to suck the fumes. I was referring to the the method of powering the vacuum cleaner you used to suck the fumes - presumably it was an electric cleaner?
If I misread the post, I apologize.

I have a Weber and when I installed it - the only remaining OE lines are the PCV and the cam cover breather. The vapor canister is still there, but vented to the atmosphere - and I have never noted a fuel odor anywhere in or around the car.
Tom M.
P.S. "OE" = Original Equipment and "OEM" = Original Equipment from Manufacturer." Pretty similar, to me, anyway.

[dlb]

man, that is EXTREMELY useful information to me. i wondered if i should have more hooked up to my weber, like the vacuum assist and such, but i read that it was best to do away with all of that. and i see what you mean and my wording, when i said vacuum hose i just meant a rubber hose, like would run to and from the vacuum assist. understandably confusing wording.

i will take the hose off of the gas vapor line then and let it vent to the atmosphere. i never noticed any smell of fumes before, i just wanted to block off everything to be sure there were no vacuum leaks anywhere--and to tidy the engine up. but hell, if it ain't broke don't fix it i guess.

much appreciated!

[ARCHINSTL]

Check some of the Weber threads - a line from the "gas filter" on the manifold still goes to the dist, as does the one on the side of the Weber. Most of us have blocked the EGR port on the manifold as well. There is no emissions testing in MO (and other, but not all, states) on "mature" cars. The only vac lines I have are the ones in this thread. And the previously mentioned PCV and vent hoses (see my thread and pix on these items).
Tom M.