Blasted Gas tank issues

[Ford_Racing_Guy]

Ok so last month my fuel lines rusted off the fuel pump/sending unit.

so i replaced it......everything was great until i started noticing a gas smell coming from the rear, i never could tell if it was dripping somewhere or not so yesterday i figured i had a day off so why not drop the tank and check everything over in case i missed something.


well i dropped it and everything was good, no hint of a gas leak anywhere.

so today i go to fill up with gas, and the pump overfills the tank, it didn't kick off until it hit 20 gallons!

so i peek underneath and bam Niagara Falls!

I have never had an issue with overfilling the tank before, why would the pump overfill it? and where would the gas come out of first to get ride of the extra fuel?

is there something wrong with the vent on top of the tank that would cause something like this to happen?

 

[Ford_Racing_Guy]

ok i've done some more searching.


could i have a defective canister purge valve that could be causing this?


this is the valve that just pushes into the top of the tank and has a small rubber hose on it correct?

 

[Ford_Racing_Guy]

no thoughts?

 

[Doubt Incarnate]

that valve should run to a carbon canister, usually under the hood i thought. maybe you have a bad filler neck seal. if it leaked it would keep the gas from going up the neck and kicking the pump gun off as normal.

 

[Ford_Racing_Guy]

and this seal is located on the plastic filler neck of the tank inside the neck?

 

[dutch724]

I have the same problem with the gas smell. I have pulled my gas tank and checked it out and pulled the sending unit off and put a new seal on it. Filled up the tank and looked for any leaks, I could not find any problems. Even while the truck was sitting in the garage there was no sign of leakage. The smell is still there. The vapor tube that is short with a cap on the end of it has no way to hook up a line to it. How do you know if that is bad.....I don't know. Any help would be greatly appreciated.
I would really like to solve this problem.

The way a fuel nozzle works at the gas pump is the little hole on the bottom of the tip of the nozzle is suppost to turn the nozzle off when it is plugged with fuel. Sometimes they work and sometimes they don't. It is not a sign that there is a problem with the car or truck. I hope this helps with why the nozzle didn't shut off.

Come on guys I know there is someone out there that knows how to solve this problem.

Thx,

 

[Ford_Racing_Guy]

i just don't understand.

i pulled the tank off yesterday and everything was fine, check all the lines and hoses...everything was good.

i just don't understand why it would overfill.......never done this before.

 

[Doubt Incarnate]

there should be some kind of gasket/seal where the filler tube goes into the tank, check that for leaks. the carbon canister is supposed to absrb the smell of gas and if its old the carbon may simply have expired and needs replaced. if the line is rotted/broken/diconected then obviously the venting isnt getting to the canister. there should be no venting to the open air, it either going in or out the carbon canister. i dont know where it is on your trucks, sorry.

 

[dutch724]

My Ford service manual says there is a line next to the short line that has a plug on the end of it called the purge port. The other line next to the purge port is the fuel vapor return line that goes to the carbon canister. The only time the purge port vents to the atmosphere is if the fuel vapor pressure is more than the fuel vapor line can vent. That is all out of the my Ford service manual......it seems I have answered my own question. There you have it! Check that line if you have one attached then check to make sure the line not kinked or broken. If all checks out ok then maybe it is the gas cap (I have been wondering my gas cap is the problem or not).
I can't remember on mine if it had a line attached there or not. That is why I plan on pulling my tank again when it warms up and I can leave the garage open. Instead of pulling the tank in a closed garage with a kerosene heater running..... Not smart!!
Don't get me wrong I vented the garage every time the fumes became strong.

 

[Ford_Racing_Guy]

anymore thoughts on why the pump would overfill my gas tank?

 

[glader420]

Here is your answer, hopefully better late than never. I just dropped my tank and replaced my fuel sending unit because the two lines that come out of the top began to leak. As I do before I perform any work the EX (affectionatly known as Flora) I comb the forums of this website to aviod any unnecessary stumbling blocks and hopefully pick up some tips. I came across your issue and allthough it remained unresolved I decided to definatly remember to keep an eye on my tank on its first fillup after re-installation of the tank with the new sending unit. Sure enough - same thing. A deluge of gas under the truck. Well, I combed the forums again and alot of the gas tank issues I read about boiled down to pressure. Also, the nozzle shut-off is partially operated by pressure. I decided that since the only thing I had changed in the system was the sending unit that it had to be the culprit of some kind of pressure loss. You see, when I dropped my tank and pulled the old unit out of the tank the metal locknut AND THE TABS ON THE TANK THAT THE LOCKUT ENGAGES were wicked rusty. I wanted a whole new tank but they are very scarce up here in the northeast in good shape that is. New ones can be found but are pricey (350-450). So I made do and used a sending unit and locknut out of an exploder in wonderful shape in a junkyard (would've used the tank too but they had punched it out to drain it). Well engaging the new locknut on my rusty tab tank wasn't pretty but I thought I got it. Not so . That sending unit needs to be totally airtite sealed like a frogs ass. The rusty tabs on my old tank weren't providing the clamping force I needed to keep the sending unit sealed UNDER PRESSURE. So I dropped the tank again pulled out the sending unit and ran a bead of some Form-A-Gasket that said it was good for fuel applications around the sending unit seat and put everything back together. Waited a day for the sealant to set-up and brought it tothe station to fill it up and it worked fine again. I even tried to overfill it this time and it would only come out the filler neck tube. So if you haven't yet solved that overfilling issue give that a shot. Good Luck and GO RED SOX!!