Gas Tank Leaking - Need Advice

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Joined
Mar 5, 2013
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Location
Carlisle, PA
My Car
-Former 70 & 72 Mustang coupes owner.
-69 Torino GT, Formal Roof, 351W, Edelbrock 600 cfm, dual plane high rise intake, long tube headers, AOD trans, dual flowmasters, Pertronix II Billet, 3.5 TRACLOC g/r, 15" Magnum 500s, 100A alt, mini-starter
-70 Mach 1, 351W, FMX
Gentlemen,

Last night my 72 was kept outside with a cover of her on a slight incline. Typically she's in the garage but upon removing the cover I smelled a very strong gas odor. I also noticed drops of gas formed on the tank's bottom ridges and a puddle underneath on my asphalt driveway. I've noticed incredibly horrible fuel mileage recently but though it might possibly be due to upgrading to a 4BBL carb. Apparently there was more to it.

My gas is also pretty discolored so it may be time to replace the tank indicating my tank is full of rust. I replaced the tank on my 70 without issue, but clearly the 71-73 are very different. I can afford the new tank and don't want to go through the hassle of cleaning out the old one.

Does anyone have a recommendation on which fuel tank to get and from which distributor?

KR

 
If I recall correctly i got mine for our 71 conv. from OMS, Ohio Mustang. Good fit and no problems installing.

 
If its the orig it may be time to change out the tank as it is not too hard a job ,

Don (Ohio Mustang) and CJ Pony Parts are both members here should have them

 
Changed mine out Sat with the help of a member here. You can see the post with pics from sat afternoon. Most suppliers sell the canadian made tank. Looked like a perfect copy. I bought the kit wih sending unit. The supplied o-ring was not good so order a seperate one for the $2 bucks, ans another one for swappin in your old vent cap on the top. It is not included with the kit. And you will need to clean the vent! Heh heh. You should certainly pick up some SAE 30R7 hose and some stainless steel hose clamps in the mean time and swap in a new piece now. You'll be doing it either way. I believe it is 5/8 hose. Youll need around 2.5 feet or so for the vent, sending unit, and the piece up front. Well worth the $150 in parts plus shipping and the couple hours to get it done. Good luck!

 
Last edited by a moderator:
pretty easy job, there are 2 straps that hold the tank to the trunk floor.

on top of the tank is a rubber hose connected to the fuel vapor system.

buy the premium replacement tank from OMS or another vendor, that has the galvanized finish so it won't rust.

drain the old tank.

pull the wire connector off the fuel sender on the drivers side.

pop the seal ring on the fuel sender and inspect the sender for damage or rust. if it looks good you can reuse it otherwise you can get a stainless steel replacement.

use a car jack under the tank support the tank.

unscrew the gap cap, pop the 5-6 hex head screws that hold the filler neck to the taillight panel.

pop the 4 Phillips head screws on the tank floor that hold the rubber seal to the trunk floor.

wiggle the neck make sure it is free, pull it out. the rubber floor seal should come out and there will be a cork ring gasket on the back side of the tail panel.

pop the 2 bolts just behind the rear valance under the truck floor, that will release the 2 straps that hold the tank.

drop the tank slow.

get enough clearance so you can pop the rubber hose off the top of the tank or cut it with a hose cutter.

drop the tank.

once the tank is clear pop the top ring on the tank and pull out the fuel vapor cap they DO NOT MAKE THESE you need to save it.

with the new tank, you should get 2 o rings. there should be 2 retainer rings as well.

sometimes they sell complete kits but you want to add.

1) tailpanel cork gasket.

2) rubber filler neck seal to trunk floor.

3) some new fuel line hose.

clean out the top vapor cap usually it is full of garbage and varnish.

with the tank out inspect the vapor return hard line under the car, if it is full of fuel varnish you will want to replace it. that will not be easy with the trans and engine in the car but it can be done.

4) optional vapor return line replacement

5) filler neck gasket dougnut

you can use some motor oil to lube the orings, but reinstall the top vapor cap on the new tank.

then install a length of replacement rubber hose on it with clamps so when you make the final connection to the vapor hard line it willbe easy.

Install the new filler neck gasket that goes into the tank lip, now you can accidentally push that gasket into the tank and it will fall in,, another reason not to install the sender yet,,, so you can reach into the tank and grab the gasket if you have an accident

you can install the fuel sender last if you wish to prevent damage during install.

(also you can replace the sock on the sender if you wish)

jack the tank into place, now here is the issue.

the straps molded themselves to fit the old tank the new tank is slightly differently shaped, you have to kind of rebend the straps slightly to fit the tank and it will be a big Pain in the butt but they will fit once you get the nut or bolt started on the straps then you can torque everything down.

put some oil on the filler neck gasket and then start to push that filler neck back in, make sure you preinstall the rubber floor gasket on the filler neck just push it up out of the way as you install it into the tank.

remember to put the cork gasket back between the filler neck and the tail panel, reinstall the screws.

now with the tank and filler neck and the truck seals all back together install the fuel sender.

connect all hoses.

Fill tank with 5 gallons of gas. let sit,,,, inspect for leaks.

the sender can leak from a couple of places so the replacements are known to leak from the electrical connector rubber seal. if it leaks you need to drain the tank, and pop the sender and replace it or figure out why it is leaking.

(i had to replace my replacement sender 2 times before i got a good one)

now with no leaks and 5 gallons of gas get into the car, put the key and turn to accesories or run,,, not start yet.

look at the fuel gauge it should read 1/4 full approx.. if not you have to pull the sender out and start bending the float draining and refilling the tank... over and over and opening the sender oring seal over and over.... yup it sucks i gave up. my fuel gauge is only accurate to within 1/4 of a tank. when i get to half on the gauge i know i'm about 1/4" from empty,,, yippy :(..

once you have had enough of that,, start the engine inspect for leaks,,, no leaks go for a spin fill up with new gas.

for the next few days give everything a inspection to make sure nothing is weeping or leaking, yhea it can happen, everything is made in china now.

 
I purchased a new fuel tank from CJ Pony Parts in 2005. The part number at the time was FT 5 (may still be the same number) as well as a fuel tank kit, FTK 4, the fuel filler pipe body gasket, HW438, the sending unit, FSU4, and the filler pipe seal in tank, FPS1. They had a bundled price of $154.95 in 2005. The fuel tank still looks like new in 2013! The only problem had was after a couple of years the sending unit started seeping fuel and it had the wrong angle on the hose bib. I eventually replaced it with one from Ohio Mustang.

 
Gentlemen,

Thanks for all the replies. I'll have one in the mail shortly and hopefully burn off some fuel without setting the car on fire.

I smelled fuel in the car on the way home, but she's not leaking anymore. I filled her up the night before she left a puddle on the ground but I'm taking no chances. Special thanks to 72HCode as always.

KR

 
re new to respond to your question-when I broached your problem, I overlooked the matter of so many changes instituted to my mustang, it became truly a resto-mod mustang re to serve my needs as in comfort performance+ as well in handling and sensibley becoming efficient ie mpg w/out loshng the thrill of extreme torque w/accelleration. As I changed over from carburetor to an EFI which matched my cleveland like the De Thomaso Pantera resorted to the Bosch L-Jetronic Fuel Injection w/a 4.11 rear end and a strong 5-speed transmission. W/a tested 26 mpg highway. I look fwd to a turbo. Re need of an EFI system. W/theEFI it was time to change over to a 20 gallon tank that was not available but the ford garage i entrusted to farm out the aftermarket tank to be prepped w/a baffle in the bottom of the tank, was disregarded so now I either replace the stock tank before venturing a long trip re non efi tanks have chance of the fuel sloshing and choking the fuel to the motor if i corner w/under half a tank. For me, if there room at the engine and the bay for a secondary tank which Edelbrock may have might be a faster and more lucrative option rather than leaving the mustang w/the garage for who knows how long-by the way happy kNew year

 
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