Gas Tank question

[bladerunner]

Need some help with an issue with my driver's side gas tank.  I am afraid my gas tank is leaking, though the tank is a 2 year old after market replacement.  The filler neck however is original and I think it might be my problem.

Anyway, so sometimes when I go to pump gas, I insert the nozzle and begin to pump gas and the pump immediately shuts off, just like if your tank is full.  When this first happened I figured the pump was messed up, but it has happened enough now that I know the issue is tank/filler neck and not the pump.  The only way I can get the pump to work is either to pump very slowly or to jostle the pump nozzle around until I can pump full speed.  I started to notice after this that my truck will reek of fuel.  So I get underneath it and check the tank and sure enough, there is a small amount of gas on the ledge around the middle of the tank.  So by now I am worried I have a leak. I will clean up the spill and get rid of the smell.  When I can pump normally, without the stopping, I do not get the gas smell or see a leak.  This only seems to happen maybe 10% of the time.

I am in the habit now of peeking under the wheel well when I pump, looking for any leaking or run off, but I don't see any. The filler neck does have a small perforation due to rust , but it is not located on the shaft of the neck, but up by the filler itself.  I am tempted to replace the filler neck and see what happens.  I have also checked the tank and it looks good, but I suppose it could have a leak, that is really what I am trying to figure out.  Any ideas?

[jaredts]

It sure wouldn't hurt to fix the filler neck if you know its badly rusted.  If you only notice smell and wet spots after filling, I think there's a good chance that's it.  If you still have the problem, nothing lost.

[bladerunner]

Chris, do you sell filler necks?

[zieg85]

There is a chance your vent hose is crimped or has a restriction in it , been there. 

[bake74]

There is a chance your vent hose is crimped or has a restriction in it , been there.

     Might be why it is backing up, and if your filler neck is rusted and has any kind of hole in it, the fuel might be running down it till it reaches the rim of the tank where you see the gas at.
     My vote would be to replace the filler neck and put on new gaskets.

[slammed79]

Funny what happens when you look around a bit. And not to thread jack, but I've got the same thing going on, minus the rust. Everytime I try to put fuel in, I get about half a gallon in, it will click off and puke out. I changed the rubber hose from the neck to the tank and the vent hose, I still have the problem. My filler neck looks okay inside. I'm confused!

[DnStClr]

Like zieg says, there's probably a restriction in the vent. Remember what you're trying to do-  you're trying to replace air in the tank with gas. If the air can't escape, the gas won't go in. It's physics-
Some guys turn the fuel nozzle upside down to get the gas to go into the tank. 

[bake74]

     It depends on the type of gas pump and style of handle you are using.  In Ca. and the western states I have this problem with my 74, you have to go slow or else it just spills out.  (I have had mine apart 3 times, it is due to the sealing of the nozzle and the bend in the filler tube.) 
      Now in Utah and eastward I have no problems filling my 74, so it has to do with the type of gas pump and handle you are using.

[Captkaos]

I don't have a source for filler necks other than used that I come across. 

[DnStClr]

Would this site work?
http://www.fillernecksupply.com/servlet/the-1391/76-77-78-79/Detail

[bake74]

Would this site work?
http://www.fillernecksupply.com/servlet/the-1391/76-77-78-79/Detail

     Nice find DnSTClr.   

[slammed79]

Stellar find Don! Thank you!

[bladerunner]

Resurrecting an old thread I started, but this is the same issue. So I was noticing gas leaking out from the top of the driver's side tank and trickling down the side facing the frame rails. I though there might be an issue with the filler neck (which was badly rusted) or the vent hose. I got a new filler neck, filler hose and vent hose on, but the leak remains.  I also have back pressure in the tank as when I go to fill, the pump immediately shuts off. I have to turn the pump nozzle a bit to get it to go. I have double checked and the new vent hose is clear.

Again the leak seems to be coming from the top of the tank, so once I get the fuel level down, I will drop the tank and see if there is an issue there.

I have also had issues switching between tanks, like it won't switch over. That would not be related by chance would it?

[bd]

Fuel may be leaking past the fuel sender o-ring.

The fuel nozzle kicking off unless in a particular position is common and may be related to the nozzle configuration.  Try filling at different stations.

The switching between tanks problem is a separate issue.