help dropping the gas tank!!!

[AaBryan]

So to drop the gas tank on my 98 I have to drop the rear end/axle (dumbest design ever?) but I'm concerned as to how much I have to actually unbolt to get the rear end out of the way enough.

Should I take the driveshaft out? Do I have to unbolt the rear sway bar?

any help would be greatly appreciated




and yes, I'm replacing my fuel pump, and NO... I'm NOT hacking a hole in my bird to do it!

[bills98ta]

I think you just undo the right shock, to drop the rear low enough to remove the right coil spring. The tank has to slide through there because of the filler neck being one piece...
If I have to drop mine again, I'm hacking a hole... Be careful of the plastic fuel lines, not to kink them...

[AaBryan]

That seems like it should work, IF I could get the rear exhaust section out, I can get the car high enough off the ground to remove the rear portion of the exhaust. So the exhaust is taking up the space where the coil spring used to be.

This is actually pretty funny how much stuff has to come off the car to get to the fuel pump. Reminds me of the replacing the heater core in my Audi. lol

[Sas]

Good luck! I had to do that on my old Trans Am and it sucked, it'll be less trouble if you just drop the rear axle out, not just one side of it.

I don't remember what all had to be unbolted to get it out, otherwise I'd try to be more helpful. Just make sure to have a friend help, becuase the axles are heavy.

[JWSmythe]

Honestly, I had to do it 3 times in my '98 TransAm.

It goes something like this. Don't look at the shop manuals like gospel.

I'll go through the right way first. Then I'll go through the better way, that you may not like. This is from memory, so my apologies if I miss something.

You'll want a good friend close by, who knows what you're talking about. You'll likely have both hands, too busy to crawl out and get something. You'll also need a hand on several of the parts.

Lift the whole car as high as you can get it (at least 2') You're going to be laying on your back, trying to maneuver the tank with your arms and legs. You'll look like a dead cockroach while you're doing it, but it's what it takes.

Disconnect the battery. A little oops and a spark will ruin your day when playing with gas.

Drain the gas tank. You want as little weight in there as you can. Siphon it and store it, or put it in another car. If you're lucky, it died when the tank was empty. Mine was at less than 1/4 tank, so it wasn't too bad. The tank itself isn't very heavy, but at roughly 8 pounds per gallon, the gas can weigh a lot, and will slosh, making it difficult to maneuver.

Disconnect the exhaust system under the passenger seat, and pull the whole muffler and pipe out. Make sure you have room, it's long.

Remove the rear tires, and disconnect the rear axle and suspension. That is, the U joint, sway bar, shocks, etc, etc. You'll need to be SURE to have a floor jack under the differential (like gravity still works, and that's heavy.)

Unbolt the tank straps, and lower the tank a little with another floor jack. Disconnect the wiring harnesses and fuel lines (Mine had 4 lines, I believe some have 3). Tag everything, so you can put them back in the right places. There are 4 fuel lines, they have to go back to the right places.

Actually getting the tank out will be a bastard. It has a solid neck that goes up through the body to the fuel door. This is where you'll be doing the dying cockroach dance.

Once you get it on the ground, you can swap the fuel pump.

A few things on the fuel pump. One after market one I received only had one hose clamp, and that's exactly what was indicated in the instructions that came with it. When I put it back together, it started exactly once before it blew the hose off inside the gas tank. The second fuel pump I got (the first died in 6 months) didn't have a fuel pressure regulator, and I didn't carefully inspect it. Make SURE you have a pressure regulator on there, or the car won't start (obviously).

Be *VERY* careful when you R&R the pump. If you bend the sending arm for the fuel gauge, it'll never be right again. Also, be careful of the yellow end. That is a styrofoam float. If you break a little off, the fuel gauge won't read right either.

Now that you have the pump in, you have the hard part. It was hard to get the tank out. it's harder to convince it to go back into place. Once in place, I held it with one knee, while I started the tank strap bolts. Again, not a fun game.

Before you put the rest back together, make very sure there is NO fuel on the ground, and have a fire extinguisher handy. Start the car. It'll start with no exhaust pipe. Just make sure it starts. If you missed hooking something up right, this gives you the chance to fix it, without taking the exhaust and axle back off.

This method takes about a day, unless you're in a proper shop, with practice pulling the tank.

Now the practical method. After spending a full day to R&R the pump, I wasn't going to do it again to find out what went wrong.

Get a good idea where the pump sits. It's in the middle of your deck area. There are photos online of people doing this.

Get a large drill bit. Also get a couple 2x4 wood blocks. You want to block the drill, so it can't go more than about 1/8" through the sheet metal. Basically, drill through two 2x4 blocks, so you can't possibly push too far through. Otherwise, when you pierce the body metal, you'll hit the tank. You don't want a hole in your fuel tank.

I started at the passenger side rear corner of the 12x12 hole that I cut. There are no fuel lines or electrical connections here.

Use tin snips to cut approx a 12x12 hole. Do NOT use a dremel, cutoff tool, or anything else that doesn't give you absolute control and feel. Make sure you know which side the snips curl on. You want to curl the piece you're removing, NOT what you're leaving. Peek through the hole, so you can see that you're on target.

Once you have your 12x12 hole, the tank pump and it's connections will be staring at you. You can be nice and comfortable sitting in the back of the car, swapping the pump.

Tag the fuel lines and disconnect them. Disconnect the electrical harness. R&R the pump.

When I did this, I didn't give myself enough room on the fuel line side, so I went back and cut another inch off, so it was easier.

Once the pump is back in, you could theoretically drive it. start it to make sure all is well. Keep your windows/doors open, because you now have a hole into the body of the car, and could get exhaust fumes in.

Go to Lowes or Home Depot, and get:

1 piece of flat sheet metal. It's not expensive.
Some weatherstripping (enough to go all the way around the hole)
A whole bunch of short self tapping sheet metal screws. You'll be able to estimate the length, because you can now see how far the tank sits from the body. I believe I used 3/8" self tapping sheet metal screws.
Rustoleum paint, preferably something that kinda matches your car. It doesn't matter, but I like to make it look good.
Wide masking tape.

Cut the sheet, so you now have a patch that overlaps about 2" on all sides.

Stuff newspapers, shop rags, or whatever under the area that you cut. Jam it in, so it doesn't actually cover the cuts. Be careful, these edges are sharp.

Paint the edges of the what you cut. You don't really want to make an excuse for rust.

Paint the sheet metal. I painted both sides, just in case.

Give the paint plenty of time to dry. There's no reason to mess up now. Let it dry overnight.

In the morning, put down the weatherstripping on the body of the car, right at the cut edge. You're sealing against exhaust fumes coming into the cabin.

Self tapping sheet metal screws are great. Just put a philips bit in your variable speed drill, and put them in. I put one every inch, but that was probably overkill. Don't overtighten the screws, they'll strip pretty easily. If you strip a few, it's ok, you have a lot of other ones holding on.

I painted again over the screw heads. Let this dry too before you continue.

When everything is dry, lay the original carpet padding, and carpet back over the hole. I banged on it, to see if I could tell the difference in sound. I couldn't tell where the access panel was through the carpet.

You're now good to go.

On mine, like I said, I used an aftermarket pump. That died 6 months later. I was so happy that I had the access panel. I ordered a new pump, and when it came in, I had it swapped in about 20 minutes. It only took that long, because I used so many screws. Now, swapping the fuel pump in the future is something I can do in a parking lot in a few minutes, rather than disassembling my car in the garage.

Good luck.

[ta02zx10r]

holy crap that was a novel.

[JWSmythe]

If it helps someone out, it was worth it.

[RyanJM]

I actually put a plate over it and sealed it with some SEM panel ashesive i had levt over from a car I did some bodywork on. After that I covered the whole hatch area with some no-name dynamat. Just as good without the high price. E Bay $75 for enough to do 2 layers over the hatch area even inside the spare area. Had enough left to do a layer over both doors as well and still have some left. Hides everything away and keeps some of the road noise out since this is a GM there's plenty.

[AaBryan]

Thanks every.. very helpful indeed!