Fuel tank removal

[IndyJimW]

Its time to remove the fuel tank from my ’87 Avanti, my goals are:

1. Stop gas fumes from getting inside car when the tank is full.

2. Get my fuel gauge to work correctly.

3. Replace all 20 year old hoses.

4. Install a pump in the tank for a TPI engine upgrade.

I started by draining the fuel tank, you will need to remove the fitting from the bottom of the fuel tank to allow the fuel tank to be removed later, I would install a flush hex head plug to prevent any fuel that is left from spilling out onto the interior when you remove

the fuel tank. My fitting had a screen and I was glad to see that it was clean. Next remove the front seats, center console and rear seat to give you enough room to move. After removing all the screws that hold the fuel tank cover in place it pried out easily, no sealer was used by the factory on my Avanti. The sound deadening foam had been continued from under the carpeting and glued to the front of the fuel tank.

Around the fuel tank pink insulation had been installed, it was matted from being wet. I removed all the insulation and cut away the foam that was attached to the fuel tank.

My stray bolts were rusted so I soaked them down with penetrating oil several times while I worked on other things. Disconnect the wiring from the sending unit and trunk and move it out of the way.

There are 4 different rubber hoses that go to my fuel tank and all of them were hard to the touch.

1. Fuel supply hose - At the bottom center of the fuel tank to a line on the frame that goes to the fuel pump. I replaced it when I first got my Avanti because it’s the only one that you can see.

2. Vent hose – Metal lines attach at the top of both ends of the fuel tank then connect together with hoses and a tee at the center top of fuel tank, the hose then goes out a hole on the drivers side front of fuel tank compartment to a metal line in front of the drivers rear wheel and up to the charcoal canister.

3. Fuel return hose – Comes from a line connected to the fuel pump and travels down the frame to the front of the passenger rear wheel, a hose connects to this metal line goes into the fuel tank compartment at the passenger front on tank and attaches to a fuel return fitting on the passenger top of fuel tank.

4. Fuel inlet hose – Large hose from fuel inlet to top on fuel tank. I noticed staining at the top of the tank and assumed it was causes by this hose.

I disconnected all the hoses and pulled the vent hose and fuel return hose into the fuel tank compartment.

The vent hose contraption has to be removed from the top of the fuel tank before the fuel tank can be removed. Disconnect the metal tubes from both ends of the fuel tank and then the nuts holding the supports to the studs in the fuel tank; remove all the pieces from the fuel tank compartment.

Disconnect the fuel return hose from fuel tank fitting and remove.

Disconnect the fuel inlet hose from the fuel tank. You will need to detach it when you remove the fuel tank.

I cleaned the fuel tank strap nuts and before trying to remove them I coated them with CRC Freeze-Off penetrating oil, both nuts came right off. When trying to remove fuel tank strap nuts, STOP if you see the strap start to turn with the nut, if not you can twist the strap and break it.

From the outside of the Avanti I removed the fuel cap, leather drip cover and the 5 screws holding the fuel inlet nozzle, pulling up I disconnected the fuel inlet hose from the fuel tank. The fuel tank is then free to remove from the car. I left the straps in the car because I didn’t want to chance breaking them by trying to remove the rear rusted strap nuts.

With the fuel tank out of the car I examined it for fuel leaks, there had been puddling on the top of the tank at the fuel inlet, but the inlet hose showed no sign of leakage. I made sure I got as much gasoline out of the fuel tank as possible, I then replaced the fittings with plugs, placed a metal plate and gasket over the sending hole and found a ball that would fit the fuel inlet pipe snuggly. I mixed up three gallons of hot water with some degreaser and poured it into the fuel inlet and then sealed it with the ball. Outside on the drive I carefully rolled the fuel tank front to back and end to end, after five minutes of this I removed the ball and the drain plug. I inserted a water hose into the fuel inlet and ran water into the tank for another five minutes. When the water quit draining I removed all of the plugs and the metal plate, I checked all the holes for any gasoline fumes. With all of the plugs removed I inserted into the fuel inlet the hose from my Shop-Vac connected to the exhaust side. I blew air into the tank for an hour to dry out any moisture. I picked up a cheap set of brass wire wheels and used them on my drill to remove loose rust and adhesive from the fuel tank. Because of the rust around the seams I decided that it would be a good thing to have my fuel tank tested for leaks, I installed all the plugs back into the fuel tank and took the tank down to my local radiator shop. After pressurizing the fuel tank they found that the seam were alright, but I had two leaks at soldered joints, the main one was at the base of the fuel inlet pipe and the other was at the fuel return fitting. They soldered the fuel inlet pipe, and removed the fuel return tube (the new TPI pump kit has a new larger fuel return fitting) and soldered a plate over the hole. If I hadn’t pressure tested the fuel tank I would never have found the cause of my gas smell, the solder didn’t look cracked or bad in any way.

The shiny spot is where the inlet tube was leaking.

My fuel gauge stopped working correctly and with the fuel tank removed now was the best time to fix it. Make sure that the fuel gauge is powered, fuses good etc. Using the two wires from the sending unit you can test the wiring and gauge. My Steward Warner gauge uses resistance between 33 – 240 Ohms.

33 ohms across the wires will cause the gauge to read FULL, 240 Ohms across the wires will cause the gauge to read EMPTY. I have a Borroughs BT7707A Instrument Tester to test gauges, but you can accomplish the same thing with resistors from Radio Shack. A pack of 5 resistor costs a dollar. A package of 30 ohm and 250 ohm resistors will allow you to check Full, Empty and if you connect several 30 Ohm resistors together in Serial you can test the gauge midways. My gauge moved from EMPTY to FULL when the proper Ohms were applied to the sending unit wires, so my gauge and wiring were OK. If your gauge still doesn’t work remove the wires from the gauge that goes to the sending unit and connect a resistor to the gauge with short wire leads and test like before, if the gauge works you have a wire problem, if not you need a new gauge.

Turning my attention to the sending unit I brought out my Ohm meter and tested the sending unit across the connectors, mine showed 0 Ohms. With the gas tank empty my sending unit should show 240 Ohms. I removed the sending unit and with the Ohm meter attached I worked the float up and down, the Ohm meter never moved from 0 Ohms, time for a new sending unit. I purchased a tube type sending unit, with no float arm this would give me space for my in tank fuel pump kit.

The new tube float is on the left, the old float on the right.

I am going to install a Chevrolet TPI system in place of my carburetor, this system requires 45 lbs of fuel pressure and since I don’t like frame mounted high pressure fuel pumps I decided to install a Tanks PA-2 Pump Module kit.

Complete Tanks kit.

I installed the kit as per the detailed instructions. A compete install can be viewed at –

http://www.webrodder.com/article.php?AID=324&SID=2

With the fuel tank clean and all modifications complete I installed all the pipe fittings and replaced the vent tubes with new lines. I recommend a product called GASOILA Thread Sealant, it is a soft set product made for gas and oil pipes, it sets in a day and gives you time to adjust fittings without ruining the seal. I painted the fuel tank with a rust shield paint to stop all current and future rust.

Before reinstalling the fuel tank I decided to seal and sound insulate the fuel tank compartment. There are two large holes in the rear corners of the fuel compartment on my ’87 Avanti, these measures 2” tall by 4” wide. I used a can of household spray foam to fill these gaps and other holes in the panels for the wiring etc. Using Dynamat I covered the walls of the fuel compartment.

I will be covering the compartment panel with Dynamat and replacing all the hoses I can with metal line in the fuel tank compartment area.

Jim Wood

[ernier]

Great post Jim. I have a terrible gas smell after I fill up and have to do the tank on my 88. The product tips will come in very handy.

ErnieR

[Charlie Kile]

Great post Jim. I have a terrible gas smell after I fill up and have to do the tank on my 88. The product tips will come in very handy.

ErnieR

Wha a great post!! Maybe it could be put in the AOAI mag?

How much could be applied to the earlier models??

Charlie RQB3932