Gas Tank Replacement (2nd try)

After replacing the gas tank and all the related vent lines and grommets, I felt confident that everything was perfectly sealed. When I went to fill the tank though it leaked out on the ground as much as ever. It turned out that the o-ring on the fuel level sender was not sealing properly.

It was easy to see where the leak was because of the paint that the gas washed off.

The second attempt was successful though. Here are the steps I followed (see the first attempt here):

• Paint tank with whatever type of paint you prefer.
• Connect breather hoses to rear breather pipes with small hose clamps (leave long for now)
• Connect filler neck breather hose to tank fitting and leave long for now.
• Install filler neck breather grommet into tank (use fuel resistant sealant if you prefer)
• Insert breather hose fitting into grommet.
• Install filler neck grommet into tank (use fuel resistant sealant if you prefer)
• Install the 2 crossover grommets (use fuel resistant sealant if you prefer)
• Install fuel sender unit (easier said than done!)
• Assemble crossover tube with fittings and breather tubes (use hose clamps and leave breather tubes long for now)
• put crossover tube into van held in place by hose holder under van (best if hose can move in the holder).
• Jack vehicle up in front as high as possible.
• Remove front wheels if desired (I found that this didn't really help that much).
• Remove spare tire and tire carrier (I feel this is the key to good access to see what is going on)
• Place tank on Jack (I duct taped an old towel to the jack to avoid scratching the paint)
• Lift tank into place (tip front up first)
• Plug in sender unit plug (don't forget this or you will be lowering the tank back down)
• As you lift the tank, feed breather tubes up over the sides of the frame.
• When the tank is in place, install tank supports (one support will hold the tank if you need to remove the jack).
• Reach through wheel wells and push crossover fittings into their grommets (use some lubrication).
• Cut the 4 breather lines to length and attach them to the vapor tanks
• Lubricate the end of the filler neck and insert it into the filler neck grommet (twist the cap toward the wheel and then rotate to the final position).
• Connect filler neck to trim ring with screws (the filler neck may be easier to install with trim ring removed).
• Cut filler neck breather hose to length and attach with a hose clamp.
• Connect fuel outlet and return lines with hose clamps.

I thought I had taken more pictures of the fuel sender, but I can't find them now. Basically what happened is that the tabs around the edge of the opening in the tank cut into the plastic on the sending unit. There are "ramps" around the outside of the sender that are supposed to pull the unit down against the o-ring.

I think there are several things that contributed to this. One thing is that the metal tabs were too sharp on the bottom side. I sanded the underside of them on the 2nd try. I also smoothed out the leading edge with a file.

Another thing that could have been part of the problem is that the pressure on the tabs was not equal all around. When you tried to twist the sender to engage the tabs, it was tight on one side, but not as tight on the other. I made a very slight adjustment to the tabs with a small pair of vise-grips. This resulted in the tabs being very snug and exerting even pressure all the way around.

Here is the sender after being installed the right way. I was surprised that after my adjustments, the sender went in with less effort than the first time (when I was actually forcing the metal tabs to cut through plastic). I didn't have to use a tool to turn it. Although it was very difficult, I was able to turn it with my hand (just barely though).

I plugged all of the openings to do a pressure test. This is a rubber stopper from the hardware store plugging one of the cross over tube holes.

After installing all of the new components I tested to make sure that the tank would hold pressure. I plugged all of the openings, and attached a baloon to one of the expansion tank breather lines with a zip tie. Then I gently blew a small amount of compressed air into the tank. The balloon remained completely inflated for at least 15 min.

I attached an old towel to the top of the jack. This worked well to lift the tank without scratching the new paint and undercoating. I used duct tape to hold it in place.