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Alright, so my girlfriend has an old beat up 1990 RS, A4 that she's making me fix up for her. Problem is it dies sometimes for no apparent reason, has to work really hard to get up to speed, and it has tons of trouble starting when it's low on gas. I'm leaning hard towards the fuel pump, and I'm not looking forward to dropping the tank. It's from the second half of the production year, so it has an electric fuel pump. I've heard rumors of some people cutting into the body from the rear hatch behind the rear seats to get at the fuel pump. My questions are: is the fuel pump a good assumption? If it is a good assumption, can I use the method described above, and where is the best place to cut? What are the best safety precautions if cutting is the best option?
Relevant info: I don't have the money to take it in to a shop right now, while I save up to get the clutch replaced on my car. I also don't have a lift, or any way to jack it up high enough to drop the tank right now. What I do have is an angle grinder and a tac-welder, a **** load of ratchets and the haynes repair manual for this car.
What I do have is an angle grinder and a tac-welder, a **** load of ratchets
Using an angle grinder and/or a welder in the immediate vicinity of a gas tank is a good idea only if you want to kill or maim yourself.
Originally Posted by VodkaVision
I also don't have a lift, or any way to jack it up high enough to drop the tank right now.
If you have a jack and a pair of jack stands you will have the rear end high enough to pull the gas tank but make no mistake, it needs to be about as high as you can get it.
Originally Posted by VodkaVision
is the fuel pump a good assumption?
Replacing the fuel pump is a major job so I wouldn't blame the fuel pump until you can get a fuel pressure reading. You want to check fuel pressure during cranking, idle, while driving and accelerating. You can also just power the pump on and check the fuel pump for a quick check.
Originally Posted by VodkaVision
I've heard rumors of some people cutting into the body from the rear hatch behind the rear seats to get at the fuel pump. where is the best place to cut?
Cutting into the hump behind the rear seats is a bad idea. Unless done properly it will only lower the value of the vehicle. Heck even when done properly you will still get frowned upon by some people.
I found mine this way and was forced to correct it.
I had to drop the tank and spend a few hours making mine. I used 18 gauge steel and cut it in an oval shape to decrease the possibility of cracks. It has an overlap where I have weatherstripping installed between for an air tight seal. I used riv nuts with machine thread bolts to hold it in place.
I also added new connections so the pump is easily replaceable. Doing it right this way is a big project since it requires dropping the tank, welding, drilling and riveting, cutting and flaring.
Using an angle grinder and/or a welder in the immediate vicinity of a gas tank is a good idea only if you want to kill or maim yourself.
If you have a jack and a pair of jack stands you will have the rear end high enough to pull the gas tank but make no mistake, it needs to be about as high as you can get it.
Replacing the fuel pump is a major job so I wouldn't blame the fuel pump until you can get a fuel pressure reading. You want to check fuel pressure during cranking, idle, while driving and accelerating. You can also just power the pump on and check the fuel pump for a quick check.
Cutting into the hump behind the rear seats is a bad idea. Unless done properly it will only lower the value of the vehicle. Heck even when done properly you will still get frowned upon by some people.
I found mine this way and was forced to correct it.
I had to drop the tank and spend a few hours making mine. I used 18 gauge steel and cut it in an oval shape to decrease the possibility of cracks. It has an overlap where I have weatherstripping installed between for an air tight seal. I used riv nuts with machine thread bolts to hold it in place.
I also added new connections so the pump is easily replaceable. Doing it right this way is a big project since it requires dropping the tank, welding, drilling and riveting, cutting and flaring.
Got it. I have some 3 ton jacks, do you think those will be tall enough to get that tank out? I really don't care about resale value, because it's already in such **** condition, and my girlfriend plans on driving it into the ground. She's had it for 19 years now and has been taking care of it about as much you would expect from a girl who has no idea how to take care of a car. The overcoat is gone, and the red is ****ed. When I drained the rear diff, the gear oil came out about the consistency of water and looked like it hadn't been changed since she got it. If I don't have the clearance to drop the tank on those 3 tons, you think I'd be better off getting some metal sheers, or some taller jacks?
You should have enough height to pull the tank out with those jacks and stands. You will need to pull the rear end completely. Depending on the region you live in, some of the hardware may be seized together. My car was a central Illinois car so the first time I pulled the rear suspension much of the hardware was rusted and seized. I don't recommend that you cut into the car because then you are creating a bigger project. You will have to cut the lines and add unions, buy metal and make a door that has an overlapping edge, etc. You may end up in a tough spot because if you can't do this yourself the cost to have a shop do the repair for you may be more than the car is worth.
How about instead of doing something unnecessary first hook up a fuel pressure gauge and confirm that you actually have a bad pump?
As far as "proper..." whatever. These cars were designed before FI was popular and without an access door for the pump like most modern cars. "Hacking" isn't hacking if you're improving the car, which if done correctly I would definitely include an access hatch in that category. In my case I did mine when I was swapping in a 9" ford and an LS plastic tank so I did it with all that out, but someone with reasonable mechanical skill should be able to do this OK without much hassle and without dropping the tank. If you do try to radius the edges of the cutout and make sure that the cover you make for it seals to the floor to prevent fuel fumes in the car.
It's actually fairly similar to yours without your patched area, more squared off, radiused corners, rivnuts, brushed cover... I even etch primed mine before putting it together to make sure there was no real chance of rust and made a gasket for to seal it. Mine is further back and was I was forced to make it bigger going up to the ribs because of the 4th gen tank's different access location and larger size.
Cutout and primed from underneath. The corners are 2" radius holes, they just look funny because they go through the floor contour. I covered any exposed metal with etching primer.
Just so you can see how the LS1 plastic tank fittings line up. I had the AN line adapters but they were didn't work as well as you'd expect. The FI style hose and clamps hold really well.
This was done about 2am a the end of my driveway... rivnuts installed, gasket made... I didn't have any of the right color touch up paint. Yes, I am sitting on the hump straddling the thing.
Just for future if anybody searching, rear end does not have to be fully out. I did not want to deal with bleeding brakes, so the whole thing stayed on the ground.
I've done mine with the rear in the car too, but I found trying to work the filler neck around was a PITA. Next time I'd just yank the whole rear. It's always SOMETHING!
I've done it with the axle in the car and without disconnecting brakes. But be sure you have the car jacked up really high, and drop the axle really low, unbolt the brake line brackets, shocks, sway bar ECT, you need ever inch to get the filler neck out.
If you do an access door, it better look like the ones posted here. No excuse for a hackjob like 99% of these jobs. The car was not designed to have a hole there and the floor pan acts as a firewall in the event of a fuel tank fire. A crappy chopped hole will allow fuel, fumes and fire to enter the cabin without a properly sealed door. The fuel lines need to be properly flared for the pressure involved too, hose clamps and rubber hose are not correct for the feed and return lines.
I've done it with the axle in the car and without disconnecting brakes. But be sure you have the car jacked up really high, and drop the axle really low, unbolt the brake line brackets, shocks, sway bar ECT, you need ever inch to get the filler neck out.
If you do an access door, it better look like the ones posted here. No excuse for a hackjob like 99% of these jobs. The car was not designed to have a hole there and the floor pan acts as a firewall in the event of a fuel tank fire. A crappy chopped hole will allow fuel, fumes and fire to enter the cabin without a properly sealed door. The fuel lines need to be properly flared for the pressure involved too, hose clamps and rubber hose are not correct for the feed and return lines.
Am I the only one who doesn't think it's that bad of a job? I read so many horror stories before we did mine.
We removed the rear wheels, removed exhaust, removed panhard bar and endlinks, lower shock bolts, brake line brackets and used a transmission jack to slowly lower diff.
Remove filler neck bezel and gas door and with some light maneuvering it came out. Took a little under 2 hours taking our time. Figure another 1.5 hours to put it back together. WE GOT LUCKY because nothing was seized. Very surprised because the car was sitting for 13 years outside.
Not a job I would want to do in the driveway. I payed the $$$ to have my buddy's tech help me and it was done. No headaches and wasted time.
To do the hole in the trunk properly would take more time VS dropping the tank.
You're not the only one. I read thread after thread about how hard it is. It's an afternoon of work. I personally don't see the need to cut a hole in a stret driven car. If the pump needed to be changed every 1000 miles, I could understand, but how often does a fuel pump go out?
I made a huge deal of dropping the rear and swapping the fuel pump four months ago as well. Ended up not being hard at all. Just make sure you have the necessary tools and take your time.
Worst part is that you have to cut your exhaust so a shop visit is necessary afterward, that is unless you weld.
I know Menards has them. I thought Tractor supply had them and I saw Home Depot expanded their rivet section so they may also be carrying them. Otherwise Amazon and eBay are the best places. They require their own special installation tool, but it isn't much more than a regular rivet installer.
of course I'll need to take off the whole back end, and my girlfriend wonders why I hate working on GM and Infinity.
