Removing gas tank

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Joined
Oct 8, 2015
Messages
54
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Location
Denver, CO
My Car
1973 Convertible, 351C H-code. AOD swap in progress
2000 Harley Softail Standard
Hey everyone,

I realized that in order to get a handle on the underbody corrosion in my car I’m going to have to drop the gas tank. Has anyone done that? I’m not sure where to begin aside from siphoning the gas out of it, which will take a while anyhow. How do you remove a 73 gas tank?

Thanks,

Jake

 
There are 4 things to worry about.  First is the fuel sender, on the driver's side of the tank.  You need to disconnect the wire harness and the fuel line.  Next is the fuel filler neck.  You will need to remove the screws holding the filler neck to the taillight panel, and the screws securing the filler neck grommet to the trunk floor.   Make sure the filler neck is free to move about.  There is a big rubber seal attached to the tank hanging on to it.  Some WD-40 squirted in the seam can help free it up.  You might be able to pull it out, but I doubt it at this point.  Now look for two steel straps holding the tank to the car.  The forward ends of the straps are captured by some slots in bodywork on the underside of the trunk floor.  The rear ends are bolted to the car through some captive nuts in the bodywork behind the rear bumper.  You MAY be able to remove these, but after 45+ years it's not likely.  I have found it easiest to remove the rear bumper and rear valance - you can see what you are dealing with then.  Support the tank as you remove these bolts.  As the tank comes down, you will need to free the filler neck from the tank.  The straps can be twisted 90 degrees or so to free them from the bodywork forward of the tank.  Finally, as the tank comes down, there is a vent on the top of the tank with a rubber hose connected to it.  Remove the hose and your tank is free.

 
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There are 4 things to worry about.  First is the fuel sender, on the driver's side of the tank.  You need to disconnect the wire harness and the fuel line.  Next is the fuel filler neck.  You will need to remove the screws holding the filler neck to the taillight panel, and the screws securing the filler neck grommet to the trunk floor.   Make sure the filler neck is free to move about.  There is a big rubber seal attached to the tank hanging on to it.  Some WD-40 squirted in the seam can help free it up.  You might be able to pull it out, but I doubt it at this point.  Now look for two steel straps holding the tank to the car.  The forward ends of the straps are captured by some slots in bodywork on the underside of the trunk floor.  The rear ends are bolted to the car through some captive nuts in the bodywork behind the rear bumper.  You MAY be able to remove these, but after 45+ years it's not likely.  I have found it easiest to remove the rear bumper and rear valance - you can see what you are dealing with then.  Support the tank as you remove these bolts.  As the tank comes down, you will need to free the filler neck from the tank.  The straps can be twisted 90 degrees or so to free them from the bodywork forward of the tank.  Finally, as the tank comes down, there is a vent on the top of the tank with a rubber hose connected to it.  Remove the hose and your tank is free.
+1,  Good description.

 
Hey everyone,

I realized that in order to get a handle on the underbody corrosion in my car I’m going to have to drop the gas tank. Has anyone done that? I’m not sure where to begin aside from siphoning the gas out of it, which will take a while anyhow. How do you remove a 73 gas tank?

Thanks,

Jake
 Take a look at  "Tim's 73 Mach 1 rebuild thread" by timachone. Much has been discussed on this subject. 

As for getting the gas out, if you have a Harbor Freight near you or similar, buy a syphon pump. They're cheap and work great.

 
I am planning on replacing my tank in the near future also.

  I also keep around 8-12 5 gallon cans of gas at all times, pure gas with stabil.   And as I need to transfer the gas once a year or so  I picked up this pump on Amazon, added some tubing to it and now let the pump do the work, hooked up to a 12v battery jumper thingy.   I also get my '72 pure gas quite often when I am out in a 5 gallon can and use it to fuel up the mustang.  Works just as good draining a tank, did so on my Polaris yesterday to put new, fresh gas in it as I do not use it much.   https://smile.amazon.com/CarBole-Micro-Electric-Cylinder-Carburetors/dp/B079SJF5ZG/ref=sr_1_1?dchild=1&keywords=CarBole+Micro+Electric+Fuel+Pump+for+most+4%2F6%2F8+Cylinder+Car&qid=1615565719&sr=8-1

 
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I am planning on replacing my tank in the near future also.

  I also keep around 8-12 5 gallon cans of gas at all times, pure gas with stabil.   And as I need to transfer the gas once a year or so  I picked up this pump on Amazon, added some tubing to it and now let the pump do the work, hooked up to a 12v battery jumper thingy.   I also get my '72 pure gas quite often when I am out in a 5 gallon can and use it to fuel up the mustang.  Works just as good draining a tank, did so on my Polaris yesterday to put new, fresh gas in it as I do not use it much.   https://smile.amazon.com/CarBole-Micro-Electric-Cylinder-Carburetors/dp/B079SJF5ZG/ref=sr_1_1?dchild=1&keywords=CarBole+Micro+Electric+Fuel+Pump+for+most+4%2F6%2F8+Cylinder+Car&qid=1615565719&sr=8-1
That's an interesting find. I just might buy one of those.

However, it goes without saying that using an electrical pump connected to a battery close to an open gas tank, requires precautions. 

 
There are 4 things to worry about.  First is the fuel sender, on the driver's side of the tank.  You need to disconnect the wire harness and the fuel line.  Next is the fuel filler neck.  You will need to remove the screws holding the filler neck to the taillight panel, and the screws securing the filler neck grommet to the trunk floor.   Make sure the filler neck is free to move about.  There is a big rubber seal attached to the tank hanging on to it.  Some WD-40 squirted in the seam can help free it up.  You might be able to pull it out, but I doubt it at this point.  Now look for two steel straps holding the tank to the car.  The forward ends of the straps are captured by some slots in bodywork on the underside of the trunk floor.  The rear ends are bolted to the car through some captive nuts in the bodywork behind the rear bumper.  You MAY be able to remove these, but after 45+ years it's not likely.  I have found it easiest to remove the rear bumper and rear valance - you can see what you are dealing with then.  Support the tank as you remove these bolts.  As the tank comes down, you will need to free the filler neck from the tank.  The straps can be twisted 90 degrees or so to free them from the bodywork forward of the tank.  Finally, as the tank comes down, there is a vent on the top of the tank with a rubber hose connected to it.  Remove the hose and your tank is free.
Thanks Mike! Very good description, I forgot about the vent! I took a look at everything else before I asked, but it’s good to know what’s there to avoid any surprises. Thanks again!

Jake

 
I am planning on replacing my tank in the near future also.

  I also keep around 8-12 5 gallon cans of gas at all times, pure gas with stabil.   And as I need to transfer the gas once a year or so  I picked up this pump on Amazon, added some tubing to it and now let the pump do the work, hooked up to a 12v battery jumper thingy.   I also get my '72 pure gas quite often when I am out in a 5 gallon can and use it to fuel up the mustang.  Works just as good draining a tank, did so on my Polaris yesterday to put new, fresh gas in it as I do not use it much.   https://smile.amazon.com/CarBole-Micro-Electric-Cylinder-Carburetors/dp/B079SJF5ZG/ref=sr_1_1?dchild=1&keywords=CarBole+Micro+Electric+Fuel+Pump+for+most+4%2F6%2F8+Cylinder+Car&qid=1615565719&sr=8-1
Thanks for the suggestions, but honestly sucking the gas up a hose sounds less dangerous than an open gas tank and a battery. I’m also on a spending freeze at the moment, so I thought I’d use my brake bleeder to get the siphon stared and just fill 5 gallons at a time. My Taurus needs some gas, and my Harley will soon I hope. Thanks for the ideas though!

Jake

 
You don't need a pump to drain the tank, or siphon it. After you put it up on jackstands, just disconnect the rubber fuel line at the sending unit and replace with a longer hose to reach your gas can. The fuel will drain itself until there are only a few gallons left. 

Mike has it almost correct, the straps are secured with carriage bolts that slide into keyhole slots in the crossmember. You can get the nuts loose by a dozen turns or so and then should be able to slide the bolts to remove them from the frame. Be sure to pull down on the straps once they start to loosen up to keep the bolt keyed into the crossmember or they'll just spin.  

The evap filter has a hose that connects to a steel line over the rear axle, you can unhook it there before trying to drop the tank. 

 
I just did the gas tank in my 73 this weekend.

For getting old fuel out, the easiest way is to remove the hose clamp on the driver's side at the bottom of the tank and pull the rubber hose off the outlet to the tank.  Be ready to catch the gas as it comes pouring out.

Slightly less easy, but less messy, is pumping or siphoning.  Open the trunk and remove the fuel filler neck.  Then I dropped a 4ft length of clear tubing down in the tank.  Put your finger over the end of the tube and slowly pull it out.  Once you get it out far enough, you can take your finger off the end and suction will start draining gas out of the tank.  As long as the end of the tube inside the tank is under the surface of the gas, it'll keep dumping out.

You can also disconnect the vapor hose in front of the tank before you start dropping it.  You don't need to stop half way through the process and try to wiggle your hand up to the top of the tank to get the hose loose there.  The hose is about 18" long.  I disconnected the connection at the hard line and dropped the tank with that hose attached to it.  Worry about unhooking the hose from the top of the tank once you get it on the ground.

 
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