• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Dual Gas Tanks...How Do They Work?

Shevland

New Member
Joined
Apr 22, 2012
Messages
8
Loc.
Paoli
I have wanted a classic Bronco for 10 years and finally bought a 1966 just a few days ago. I know very little about cars in general but want/need to learn and I was told this would be a great place to gain an education. After owning the car for only 4 days, I already have a little situation that I could use some help with. I ran out of gas (even though the tank said their was 1/4 tank left) so I had to hitchhike to a gas station and get it solved. I am not even 100% sure if I ran out of gas. I went into a Home Depot, came out and couldn't start it, and assumed it was the gas because it was kind of getting low. It was also old gas in there from prior owner so maybe that had something to do with it. This leads me to my questions about how the dual gas tank system works...

1) Does the gas gauge tell you how much gas in total is available between the 2 tanks or just in one tank based on whichever tank you have selected on the dash?

2) Does the gas tank switch on the bash actually set the car up to pull gas from the other tank or does it do that automatically and the switch just tells the gas gauge which tank it is measuring? If it does actually switch the source from one tank to the other, does it have to be done when parked or can it be done when driving down the street?

3) Do you actually fill up both tanks? (Sidenote, I tried doing this but when I went to fill up the second tank I could see gas spirting out inside of the one I already filled in a little hole which looks like it is designed to be there for some reason, almost like an overflow vale or something)

4) Which tank is the main tank and what are the sizes of each? (I have a 66 if that helps)


Sorry for my limited knowledge, like I said I have only owned the car for less than a week and can't wait to start learning more about it.

Thanks!
 

oleguy74

Bronco Guru
Joined
Mar 26, 2008
Messages
2,034
Loc.
calif city ca
front tank is aux.rear is main.switch on dash selects fuel level for main or aux not both at same time.valve in front of drivers seat switches tanks.this is stock configuration.
 

surveyor5

Full Member
Joined
Oct 27, 2009
Messages
245
Loc.
Oakridge, OR
The valve for switching from one tank to the other is located below the driver's seat. When you are seated with your feet flat on the floor, the valve is located behind your right heel. There is ( or should be) a valve position plate behind the valve handle.
Mike
 

TwoDalesDad

Bronco Guru
Joined
Jul 19, 2011
Messages
1,515
There are two small round "caps"on the side of your bronco. USUALLY ONE IS IN FRONT OF THE REAR TIRE AND THE OTHER IS BEHIND THE REAR TIRE. THE EASY WAY TO GO...IS TO ADD 5-10 GALLONS TO EACH TANK....THEN GO FOR A SHORT DRIVE....STOPPING TO CHECK FOR LEAKAGE ALONG THE WAY. EARLY BRONCOS. DO NOT GO FOREVER ON A TANK.....BUT WITH GAS IN BOTH TANKS....YOU CAN SWITCH BETWEEN THEM....TO MAKE IT TO A STATION...WHERE GAS IS SOLD...PS....WHEN YOU PURCHASE A VECHICLE THAT HAS BEEN SITTING FOR AN EXTENDED PERIOD...START BY FILLING THE TANKS TO ADD TO THE EXISTING CRAP THAT SHOULD EVEN OUT THE DEAD FUEL...AND THE BRONCO WILL LOVE YOU IF YOU CHANGE THE FUEL FILTER AS WELL.....GOOD LUCK....AND GOD-SPEED...THESE ARE JUST SO MUCH FUN...LOL
 

1970mule

Bronco Guru
Joined
Dec 20, 2007
Messages
1,515
1. you are correct it just tells you how much is in the tank that is selected.

2. the switch on the dash only switches the gague to which sender in the tank, the actual switch for the gas to be pulled from either tank is manual and on the floor behind your foot. you can switch while driving.

3.YOU do have to fill both tanks, however these are old trucks as i read your side note and there could be some mods done by the previous owner, so some looking may need to be done.

4.main tank is in the rear, the manual switch on the floor should say which is which for switching, the one in front is AUX. AUX is 9.7 gal i believe and the rear is 12. something or 13. cant remember
 

BoureeOne

Contributor
Bronco Guru
Joined
Mar 28, 2011
Messages
3,068
Loc.
Madisonville, La
People here are also very very visual. Join and become a member, then post up some pics of what you have. As was said before, advice can only be given based on the stock set up. But if you have mods, those suggestions might not help at all. My biggest concern is your statement about putting gas in one tank, then while putting gas in the second tank you see gas coming from the first tank. Pics Pics Pics

Scott
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
Switch on the dash only controls the gauge. Reading is per tank only
Valve under the seat controls the flow of gas. Main tank in the rear, the underseat was the optional aux tank. The tanks should be completely isolated from each other.
 

BronCowie

Contributor
Old Timer
Joined
Apr 24, 2007
Messages
8,024
Loc.
Vancouver, WA
...Sidenote, I tried doing this but when I went to fill up the second tank I could see gas spirting out inside of the one I already filled in a little hole which looks like it is designed to be there for some reason, almost like an overflow vale or something...

This sounds very strange. A picture would help.

I've had gas spirt out of the tank I'm filling if I fill too fast but have never seen or heard of one tank spirting while filling the other.
 

croft75

Sr. Member
Joined
Feb 9, 2007
Messages
781
Welcome, If you have a single tank you really need to adjust your thinking from a new vehicle, I had the same problem for the first couple of months. You think no way it can be empty but realistically the tank is only twice as big as the one on my lawnmower.:p
Dual tanks will help or a 23 gallon aftermarket tank will do.
 

brianstrange

Bronco Guru
Joined
Nov 22, 2011
Messages
1,626
If simply adding gas didn't solve your problem, then....

"Out of gas" + "Guage shows 1/4 full" = check fuel line condition, look for rust in fuel tank, clogged filters, clogged carb.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,344
And on top of what they all said, your old gas gauge and/or wiring and/or sending units can be faulty too.
So your 1/4 tank might really be empty.

Or, like you were thinking, it could still be half-full but something else caused it not to start. Gummed up carburetor for one thing.

What kind of overall condition is the Bronco in? How about the wiring and stuff? All fluids changed after you bought it?
Some things to think about anyway.

The amount of gas you can get in your tanks will vary. While it did officialy vary slightly over the years, even among trucks from the same year, one might get more at a fill up than another's Bronco will take.
My '71 would barely take 7 gallons in the front auxiliary tank, and 11 gallons in the rear main.
So if yours are anywhere near that at fill up time, you're probably doing good.

Good luck,.

Paul
 
Top