It was a nice day in East Tennessee and since I had nothing to do at work I left the office early to take my '77 Bronco for a drive in country. I drove it to the family farm, and fiddled around there for a little while. When I was leaving it died on me and would not start again, since my gas gauge doesn't work I just figured it was out of gas, haven't driven it in a while and thought I had enough. Started looking around and noticed a minimal leak coming from the rear tank.

The auxillary tank doesn't work, I can't remember what the previous owner told me was wrong with it but its been on my to do list for a while and I don't want to get involved with it right now.

I started to take the tank off and have one bolt left that I couldn't reach with the tools I had on me. I'm hoping the leak is something simple like the filler hose but, If I have to replace the tank should I:

(1) Buy a stock replacement tank for $175, the catalogs I have just show they fit a 71-76 model, what is different about the 77?

(2) Buy a 23 gal replacement tank for $350 to $450. They sell a regular one and one for a 2" body lift. The bronco is stock now but I plan to eventually lift it, if I buy the regular 23 gal tank will this effect a future lift?

I'm hoping when I get a better look at it is nothing major, I'd hate to have to buy a new tank either way. What else should I look for that might be causing the leak? Thanks.

 

You need to find out where the tank is leaking.... otherwise nobody can give you a real suggestion.

If the tank itself is leaking and it is a hole.... you can buy a gas tank patch kit.... which is basically a version of soap and varnish... and that repair can last a bit.... but only would recommend if it is a rust hole.


If you are going to use a body lift, it is better to buy the 23 gallon body lift tank, you can make the 23 gallon non-body lift tank work, but you have to add a bracket that looks like a a "U" in the chanel at the rear of the frame where the rear most body mounts are that is the depth of the chanel plus 2" or weld a bracket to the tank that is 2" and wider than the chanel by 1/4" each side..... the first method is easier.

Many times the metal tank strap will cut throught the tank over time....

When you do the new tank.... go see your friends at grainger supply and get either Telfon sheets or EPDM sheets 3/16 thick and glue them where tank metal contacts mount metal like thye do at the factory.

The 23 gallon tanks are good.... but I did damage mine; probaly from hard off road use. Got the spot weld on a internal baffle to pop and cause a leak right were the tank goes from being flat on the bottom to angling up to the bumper. I was fortunate enough to be able to get my tank brazed..... which entails draining the tank, removing , filling and flushing with water, brazing and re-installing. Otherwise the tank would be a total loss.

If you decide to go with a stock tank...... your work is easy.... the stock tank can be used with a body lift because it has metal brackets mounted to the frame that hold it in place. The expanded tanks used the frame at the front and rear body cross member at the back, and have kick at the top to contact the floor... you remove the stock brakcets to use one.

Personally.... if you find the leak and it is not at the sender, or on a fill hose... I'd go stock for 175, and call you friends at classic tube or inline tube or NPD and get some stainless steel fuel lines, a manual tank swicth and rebuild the fuel system on that baby.

 

Finally got the tank off and found the leak. It looks like it is seeping out around where the strap accross the top was and near where the J -Bolt is near the sender and hoses.

The tank is poly and my understanding is they were only on the 77's (from JBG catalog), I'm assuming the other years had steel tanks. From looking at catalogs it looks like the sending units and hoses for the replacement tanks they are selling are in different locations than my stock tank. Autokrafters catalog says that I can use the aftermarket tank for my '77 but have to change out the sending unit. If I can use one of the aftermarket "stock" style tanks I would still probably need to replace the tank guard since mine is rusted pretty bad another $140. So with sender, tank, and guard, plus miscellaneous stuff I'd roughly be looking at least $350.

So, I figured it might be cheaper just to find out what is wrong with the auxillary tank. I put a couple gallons of gas in it and it appears to be seeping around the sending unit. Hopefully it's just the O-ring. I'll try to replace it and see if that fixes the problem. If I did have to replace the auxillary tank and all related stuff (which I figure would be best to do while I'm at it) I'm guessing it would run at least $250.

Thanks for the info Boba Fett, it looks like when I eventually go with the lift it would be easiest to buy the extra capacity tank then and mount it.

 

D7TZ9002K .. Main Fuel Tank-Plastic-14 Gallon / Fits: 1977 Bronco.

No Ford Dealer or obsolete Ford parts seller has a new one.

Have you tried Bronco Graveyard?

COAF9276A.. O-Ring Gasket, Fuel Sending Unit.

Fits: All the cars from 1960 thru 1979, F100/350's from 1967 thru 1979 (except w/the in cab tank sender unit), Bronco's from 1966 thru 1979.

Available from Ford.

MSRP: $0.77 / FTEpartsguy.com price: $0.60.

 

You could also get the 23 Gal tank from aftermarket that bolts in.Takes a little work but comes with new sending unit and all the parts to mount.