Filling the gas tank

[Shane]

Hey guys, I've been having issues filling my gas tank lately. I had it replaced, and ever since then I can't have the pump run at full speed. I have to take the nozzle about halfway out and run the pump at about halfspeed and that causes it not to autoshut off.

Anyways, I got this pearl of wisdom from MonteCarloSS.com and I wanted to know if it pertained to our cars as well...

Originally posted by monte12345:
[QB] Filling problems are ususally due to a blocked vent line to the charcoal cannister or a clogged charcoal cannister. If you cannot stand the low fill rate then it means dropping the tank and testing/clearing out the vent system or a new charcoal cannister. The smog nazi's won't like it but you can test the vent line by disconecting the tank line at the cannister and see if it fills at full speed, if it does - get a new cannister, if it doesn't - crawl under the car and replace the vent line all the way to the tank. Sometimes you can clear the vent line by blowing it out with compressed air but it still means dropping the tank, you have to blow it out from the tank end or you just blow junk into your gas tank. I wouldn't leave it disconnected, you may end up splashing raw gas into the engine bay.

The company that I work for does a lot of OEM fuel filler components and fuel systems suppliers call this problem premature shutoff, every filler neck made goes thru testing for this. They actually make "glass" test pipes so they can watch what happens.

The way that they determine the volume of a tank is real funky, fill at full speed to the first shutoff, wait 10 seconds, fill at half speed to the second shutoff, and that is the capacity.

One thing that is real interesting is just how large the air bubble in our tanks are, it's huge. I ran dry once and out of curiosity spent about an hour dribbling gas into the tank, the damn thing held 22 GALLONS!!! I found out later that an overfill like this is NOT a good idea, raw gas can get to the charcoal cannister and screw it up bad.

BTW, there was a recall on the charcoal cannister for certain years and you MIGHT be able to get a dealer to replace it for free. Does anyone know how long GM is responsible for recall items on emissions related equipment? [/QB]

Would that work on our cars?

Thread here.

[ULYCYC]

You could have crushed the vent lines went installing the new tank. Try another gas station first. Sometimes the nozzles are broken or the pumps are set to run too fast.

[Shane]

I have tried other gas stations, and it's the same thing everywhere.

The vent line is a possibility, I had the tank installed. Long story short, I was required to get the car towed, and then I was not allowed to put in the tank myself. Rather than leave my car in lockup, I just paid for a new tank.

[O² Cool]

I have teh same problem with my 96 cherokee. I always attributed it to a backsplash of fuel onto the filler, fromto sharp of a bend into the tank or something not a charcoal canister or a vent problem. I guess the vent makes sense but i would check first for a kinked filler hose. If the tank was improperly installed it will cause "back spray" in the filler neck and shut off the unit. It's simple to check and then from there check the vent lines

O² Cool

[ULYCYC]

Our cars have a metal filler neck. So no hose to kink

[Rickracer 1]

Look at it from underneath, and then look at one that fills easily , and see if you can see a difference.

[firebird_1252]

monte12345 is a ****ing moron.. dont listen to him. he has no damn clue what he's talking about. i cant run the pump at full speed on my gn eather.

[dyermullet]

My 87 regal that has been in the family since new was never able ot run the pump at full speed. Even off the showroom floor.

Scott

[turbofish38]

Even if monte12345 is a moron,maybe one of the reasons MCs have this problem is they are all carb'd and we are FI. A stock MCSS emissions system is vented in a way that fuel will flow back to the vapor canister through a faulty canister purge valve. I would check to make sure the vapor(or vent) line isn't clogged or restricted. Are you still running a vapor canister? If not you can put a breather type filter on the vent line to eliminate the problem.

[firebird_1252]

ok then you explain why every g-body i've ever seen and put gas in (and its been a real lot of them) they ALL have the same problem?

[dyermullet]

My Regal that has been in the family since new is a 307 carbed v8. And as I said it was never able to be run at full speed.

My WE4 isn't able to be run at full speed either.

Both these cars have vent lines and charcole canisters. The only difference in the tanks is that the FI cars have baffeling.


Turbofish, are YOU able to run the pump at the fast setting?

Scott

EDIT: Not meaning this post to sound like an attack on you. I am just stating my experience with both carbed and FI g-bodys. I am not saying it is impossible, just everyone I know with a g-body has the same problems.

[b4black]

I can run at full speed on my G-bodies if I pull the nozzle out ½ way. It's the same whether I have a charcoal cannister or not.


Pump nozzles have changed in recent years in an effort to catch the vapors. They are much more complicated than you think (I don't remember all the details). They incorporate a vapor recovery system thast doesn't seem to like the olders fuel tanks.

[dyermullet]

Another tip, if you top off after the pump clicks off, all the extra gas just goes into the vapor recovery system but you are still paying for it.

On my g-bodies I know I can pump the gas and after it clicks off put in another 2 or 3 gallons, but if I do anymore than that I am just pumping the gas into the vapor recovery system.

This tip is more for a latemodel vehicle where it can fill the whole tank on the high setting.

Scott

[ULYCYC]

Originally posted by dyermullet
Another tip, if you top off after the pump clicks off, all the extra gas just goes into the vapor recovery system but you are still paying for it.

On my g-bodies I know I can pump the gas and after it clicks off put in another 2 or 3 gallons, but if I do anymore than that I am just pumping the gas into the vapor recovery system.

This tip is more for a latemodel vehicle where it can fill the whole tank on the high setting.

Scott

I learn something new everyday. Please explain this one in more detail

[dyermullet]

The pump nozzles have the vapor recovery, where to catch the gas vapors so they don't escept into the atmosphere.


I don't remember the exact way the pump knows when to turn off, I will have to ask my dad. But if you keep filling the tank after it auto turns off, untill the gas is all the way to the fillerneck, you are just pumping the liquid gas back into the vapor recovery system. Basicly u are paying for it and it is just going back into one of the gas station's tanks.

My dad works for an Oil company and for awhile he was in charge of building new gas stations, so he knows all about how all the systems work.


Another thing that dosn't happen anymore, is in the movies when you see a car runover and knock the pumps off. They have brakeaway valves that turn off the gas flow imeadity, so you can't get that firey explosion. Same thing for the gas filler hoses, if you look at the hoses you can see that part that is designed to brakeaway.


I am sure someone on here knows how the pump knows to turn off I beleave it is from the vapors coming back out of the tank.



b4black I do the same trick as you do, I usually run it in on the auto feature, then I pull the nozzle out part way and pump some more in by hand. That's when I can afford a whole tank full.


Scott