Fuel Tank Filler Neck Position

[athawk11]

I'm mistified. �The fuel tank filler neck seems to be set to high on the tank. �

I pulled the tank a few months back. �I had to replace the floor pans. �The old pans were sagging and rusted through, but even then, looking at the old grommet, the fuel neck seemed to be set too high on the tank.

Now, the nice new flat floor pans have pushed the filler neck even higher up to where it is nearly impossible to put the gas cap on.

Can I safely cut the neck out and weld it lower on the tank? �Or am I asking for the fire department to show up? �Also, the clip at the back of the tank needs to be put back on.

If this is a job for a professional shop, what kind of shop?

Is it possible that this tank is a replacement that wasn't built right?

I am always grateful for this forum. �Any thoughts would be helpful.

Tim �

[Jesse]

We had the same problem with a reproduction tank, and my dad thought at first that it was just made incorrectly.

That might be the case, but anyhow the problem was solved by moving the tank as close to the body as possible. Just moving it over 1/2 inch (closer to the body) made all the difference in centering the filler in the hole.

-Jesse

[Bob W]

It is very likely the tank is a reproduction, many of them just don't fit. We can probably determine if it's a repro from photo of the front side of the tank.

[athawk11]

The tank currently fits like a glove between the center hump and the driver side panel.  I can't move it closer to the side panel.

I will take some pictures and try to post them.  I have heard it's not easy to post pictures unless you use a secondary photo posting site.  

If possible, I would still like some feedback on whether I will blow myself up if I try the weld on this tank.

Thanks,

Tim

[danorte]

Welding gas tanks is dangerous, however I have welded one following cleaning and then filling with water. Weldiing the full tank gives less chance of explosion of the vapors which may be left in the tank. So positioning the tank with filler neck at the highest point, fill with water to highest level making sure filler neck is cleaner than clean, ie no smell of fuel. Weld carefully. I am not sure I would do it again due to extreme stress on my heart during the welding procedure. Waiting not so much for fire folks, rather emt to bring me back. I only did it outside with plenty of room and a friend to call 911. I have seen one explode that the fellow said he had cleaned really well but he tried to weld it empty. Big mistake. It unfolded in the explosion and though did not break any bones he had the most bruising on his legs and thighs. Not telling you to do it just be very very careful of the explosive fumes. Norte

[RussellL]

A tank can be welded on safely if it has been properly gas free'd. �The process is two fold. �First it has to be washed to get rid of any liquid gas residue and then ventilated until every trace of the gas has evaporated and purged. �

I used to work as an engineer on tanker ships carrying gasoline, and we had to gas free the tanks all the time if we had to do work in them. �We would wash the tanks using special washing machines, a process that took several hours on a big tank, and then we had to rig ventilators in the tank and air it out. �That frequently took a full day or more. �Of course on the ship we had explosive gas meters to test the atmosphere in the tank to see if we had done it properly, and there were times when we had to start over and try again. �

The tank is only explosive if the air and fuel are mixed in the proper ratio. �Move the ratio out of the explosive range and it won't burn. �If you have gotten rid of all the fuel, then you need to keep the ventilation going to make sure no significant concentrations of vapor can build up. �Gasoline is so vaporous that you have to get rid of every trace to be safe, but any dirt or rust residue can still emit vapors. �Some people talk about filling the tank with water to make it safe, but even that has drawbacks. �You can never get the tank 100% full so there will always be pockets of atmosphere where vapors could accumulate.

I've heard about people using car exhaust to inert the tank and keep it from burning, but that is dangerous. �First, the car exhaust is hot and might ignite the vapors itself. �Second, if you have not cleaned the tank, then the only reason it doesn't burn is because you are excluding the oxygen. �Any reentry of oxygen and the explosive ratio is reached again. �Some ships (most of them these days) have inert gas systems on them but that is only used to inert the tank while the ship is returning empty for another load. �Never for doing work. �They use exhaust from their engine, or even burn fuel in a burner to create Low oxygen exhaust to fill the tank as the cargo is pumped out. �The exhaust goes through water washed coolers to get rid of any heat and has oxygen sensors to be sure the oxygen content is properly low. �

If It was me, I'd wash the tank with my pressure washer as thoroughly as possible. �I'd rig fittings on my nozzle so I could wash into the corners of the tank and behind any baffles. �Then I'd stick an air hose in it with the pressure regulated down to a few psi so my compressor could keep up easily and I'd let it air out for several hours. �Then I'd fill the tank with water about half way to cover part of the tank surface to reduce the chance of vapors coming out of dirt and rust. �Then I'd put the air back in and keep ventilating while I was working on it. �Without an explosimeter you can't be 100% sure it is safe, but on a small tank my nose would be a pretty good indicator of whether there was still vapors in there. �Basically, if you smell gas in the air coming out, it probably isn't clean enough. �The most important part is to be patient. �Don't cut short on either the washing or ventilating. �Thats how I'd do it anyway. �I have brazed up leaks in a tank using that proceedure. �On the ship we used that proceedure, without refilling with water of course, whenever we had to work in a tank, whether it was welding or just changing out a valve or pulling a pipe out to repair it. �But if we had to do any welding, we would have to gas free that tank and all the tanks around it, and sometimes we'd have to gas free the whole ship. �

Bottomline, if you do it right it is safe, but if you aren't sure, dont do it.  You are basically working on a bomb.  

[mud pie]

For piece of mind (and safety), looks like I'd get another tank from a reputable seller rather than weld on an old one....

My fingers/eyes/arms/life is worth more than the cost of a new tank.

[athawk11]

Okay, So once I cleaned the exterior of the tank, I found that the neck had been repositioned and brazed back on.  I believe the tank neck was once in the right place and the repair was done poorly.  

So, after reading all the posts and some additional internet information,  I did what Russel and Danorte suggested...times 3.

I cleaned the interior of the tank with ZEP Degreaser... 4 times.  In between each cleaning, I blew air into the tank for several hours... 4 times.  Filled the tank with water....got nervous... emptied the tank ... then looked at the price of a new tank.  I got brave...smelled the tank and could not smell gas.  I filled it with water to the neck....put the tank on the other side of a short wall...did a quick test weld as I ducked and covered.  No explosion.

I continued with the repair and I am here writing...so it did work.  

I will say, I have no plans on making this a habit.

Once again, thank you all for your posts.

Tim