Out of gas at 1/2 full??

[BroncoTwin]

The other day I ran out of gas. I was able to toss in two gallons to get home and the next day I drove it to the gas station to fill up but it only took 6 gallons? My gas gauge tells me I'm full when I fill up, but it runs "empty" at 1/2 a tank. Any suggestions as to why this is happening? Thanks!

 

[jedblake]

You don't mention what your running. If electric fuel pump it could be going out, ive also had them just die in my experience.

 

[1strodeo]

my gauge has never worked, so I basically go with my gut...oh and a 1-gallon gas can ;D also I have to aim the fuel nozzle a certain way, pull it out a certain amount and find the right rate of flow, which is very slow, in order to fill it.

Sorry I'm not much help, I can only sympathize. Is your tank level? That was/is one of my issues.

 

[garberz]

If it’s not a stock tank, some types of the 23 gallon tanks have a two piece pick up tube. Maybe the lower portion game off.

Mark

 

[SteveL]

Side tank is 7 gallons. Are you sure which tank you're running on? Same for the gauge.

 

[Allen_69]

I've seen rust holes on the pickup tube inside the tank cause this. if it sat for extended periods with half a tank it can cause rust at the fill line

 

[Pa PITT]

How many gallons did you put in it. & Yes care a couple gallons of fuel while you get it figured out.
........
.... I'm going to say Fuel tanks are not all that hard to remove''for a young man'' So I'd remove your tank & Inspect stuff.
I'd want to put in a new float level but not totally needed. So Some one can tell you here how to text the gauge & the level for it's ohms.
& Check to see if there is a hole in the inlet tube any place . Good time to replace the sock. Now you know if problem in in the flue gauge in dash or valve in tank .
& Put a new seal on the top of the tanks.
.... Good luck.

 

[Pa PITT]

1st rodeo & Others that have that very slow & Puke back fill rate.
... How my old RED NECK fixed my 1980 Bronco it puked back & would take 15 minutes to fill.
SO I just CARRIED 2 Blocks of wood nail together ... 2 2x12's One slightly longer than the top one . I laid it down in front of my rear tire & Pulled up on the blocks , lifting my Bronco about 3.5 inches on the side the fuel tank is on. WaLa filled 1st time every time . Pitch my block back in rear floor & BeGone.
Some times if the gas station drive was tilted enough I did not have to get on the block.

 

[DirtDonk]

What they all said BroncoTwin. Which tank are you working with, and is it original or aftermarket?

Even original tanks can lose their sock filter or have the wrong pickup/sending unit installed.
Aftermarket tanks could have been set up improperly or have other issues as was mentioned.

Your '68's stock tank(s) would have been maybe 10-12 gallons in the rear/main tank, and 6-8 in the front/aux tank if so equipped.
If you're running dry when the gauge reads half full then it's a common gauge/switch/wiring/sender issue.

All are easily fixed, but it takes a little bit of testing to figure out which way to go.
If the gauge is not reading a change at all, it's possible that you're working from the one tank while watching the gauge reading for the other. Assuming you have dual tanks that is.

Good luck.

Paul

 

[Broncobowsher]

First thought is a faulty dip tube (fuel pickup inside the tank). Cracked, rust pin hole. Draws fuel fine until it touches air and it won't pull fuel anymore.

 

[Skytrooper15]

Since you are carrying extra gas the next time it runs out see if you can siphon gas out of the tank.If you get gas by siphoning I would drop the tank and check the fuel pickup and sending unit like above mentioned.

 

[BroncoTwin]

You don't mention what your running. If electric fuel pump it could be going out, ive also had them just die in my experience.

It is an electric fuel pump but seems to be working fine after I fill up with gas.

 

[BroncoTwin]

How many gallons did you put in it. & Yes care a couple gallons of fuel while you get it figured out.
........
.... I'm going to say Fuel tanks are not all that hard to remove''for a young man'' So I'd remove your tank & Inspect stuff.
I'd want to put in a new float level but not totally needed. So Some one can tell you here how to text the gauge & the level for it's ohms.
& Check to see if there is a hole in the inlet tube any place . Good time to replace the sock. Now you know if problem in in the flue gauge in dash or valve in tank .
& Put a new seal on the top of the tanks.
.... Good luck.

I was only able to get 6 gal in when I went to fill up, but after that it ran great.

 

[BroncoTwin]

What they all said BroncoTwin. Which tank are you working with, and is it original or aftermarket?

Even original tanks can lose their sock filter or have the wrong pickup/sending unit installed.
Aftermarket tanks could have been set up improperly or have other issues as was mentioned.

Your '68's stock tank(s) would have been maybe 10-12 gallons in the rear/main tank, and 6-8 in the front/aux tank if so equipped.
If you're running dry when the gauge reads half full then it's a common gauge/switch/wiring/sender issue.

All are easily fixed, but it takes a little bit of testing to figure out which way to go.
If the gauge is not reading a change at all, it's possible that you're working from the one tank while watching the gauge reading for the other. Assuming you have dual tanks that is.

Good luck.

Paul

Thanks Paul. I only have the single gas tank, no aux, and I believe it's capacity is 14.8 gal. The gauge will move to full when I fill up but acts empty at 1/2 tank. The first time this happened I was not thinking it was a fuel problem because my gauge was not on empty. I ended up removing the oil bath air filter to check the carb and noticed gas was not making tom the carb leading me believe I was empty. Looks like from the other posts, I have some more investigating to do. Thanks.

 

[SteveL]

Your neighbor decided to quit paying for gas

 

[DirtDonk]

It is an electric fuel pump but seems to be working fine after I fill up with gas.

Where is it mounted and how is it wired? And what type is it?
Just wondering out loud it if's up high and relying too much on the siphon-effect to get gas to it. Most (all?) electric pumps are more efficient at pushing fuel than they are at pulling it. So those mounted towards the front of the vehicle, and/or up high, can have issues.
There are a few members here that are very lucky and their pumps mounted up on the wheel wells and firewall work fine. But in most cases, that does not work for long. Been tried, found wanting...

Is your Bronco a '77? If not, and I think you said it's a '68(?) then you'd be the odd exception to the tank size rules. The '77 was the only officially 14gal version and all the rest were somewhere around the 10-12 range. Some books show them varying by years, while others have them all pegged at about 11. My '71 was always exactly 11 when I drove it to bone dry.
But even that 3gal difference does not explain away your issue. However what the others have already said would. The pickup tube not reaching the bottom, the size of the tank being compromised, the pump mounted in a bad place or some variation of those thoughts.
And that assumes you can fill yours up fully, which many can not do.

Is it a stock tank?
With an assumed 11gal for now, filling it with 6gal means that you're leaving 5gal in the tank when you start having trouble. This might be consistent with the sock filter going bye-bye, or the metal tube rusting off part way. I've seen this multiple times where the pickup tube can no longer reach anywhere near the bottom of the tank.
If none of the other stuff pans out, maybe pulling the tank is in your future to check inside.

Paul

 

[BroncoTwin]

Where is it mounted and how is it wired? And what type is it?
Just wondering out loud it if's up high and relying too much on the siphon-effect to get gas to it. Most (all?) electric pumps are more efficient at pushing fuel than they are at pulling it. So those mounted towards the front of the vehicle, and/or up high, can have issues.
There are a few members here that are very lucky and their pumps mounted up on the wheel wells and firewall work fine. But in most cases, that does not work for long. Been tried, found wanting...

Is your Bronco a '77? If not, and I think you said it's a '68(?) then you'd be the odd exception to the tank size rules. The '77 was the only officially 14gal version and all the rest were somewhere around the 10-12 range. Some books show them varying by years, while others have them all pegged at about 11. My '71 was always exactly 11 when I drove it to bone dry.
But even that 3gal difference does not explain away your issue. However what the others have already said would. The pickup tube not reaching the bottom, the size of the tank being compromised, the pump mounted in a bad place or some variation of those thoughts.
And that assumes you can fill yours up fully, which many can not do.

Is it a stock tank?
With an assumed 11gal for now, filling it with 6gal means that you're leaving 5gal in the tank when you start having trouble. This might be consistent with the sock filter going bye-bye, or the metal tube rusting off part way. I've seen this multiple times where the pickup tube can no longer reach anywhere near the bottom of the tank.
If none of the other stuff pans out, maybe pulling the tank is in your future to check inside.

Paul

Hey Paul. Thanks again for the info. I put a couple pics in my garage of the fuel pump location. Looks like the PO placed it on the driver side wheel well. When I turn the key to the on position I can hear what I assume is the fuel pump making a soft clicking noise, if that makes sense.

I'm not sure if it is a stock tank, but I can find out from the PO. it doesn't look that old. I included pics in my garage of the 1968 Owners Manual (reprint) where I got the fuel tank capacity information. I'll try to rule out all other causes prior dropping the tank. Thanks again.

 

[DirtDonk]

That's really interesting about the 14.5gal capacity!
I knew some books show more capacity on the older ones (before evap canisters in '70) but I've never run across one that could be filled that high. I have a '68 book too and didn't note that. Unfortunately (actually, very fortunately for me!) when I got my '68 it already had a larger aftermarket tank installed, so I can't verify the original capacity.
My '71 is already after the cutoff and never held more than 11gal when bone dry.

Regarding the pump, you may just have been one of the lucky few where when the pump was new and strong it could pull all day long. But that location is a classic spot where most other people have had nothing but trouble being able to feed their carburetors reliably.
I don't want to make you do work unnecessarily, but if it continues to work fine with a full tank of gas, but give you trouble when it gets down to half full, I'm going to say I would move the pump back to the frame near the tank.

It's where 100% of the fuel pump manufacturers would tell you to mount theirs. In fact they even state specifically to mount it lower than the tank (as if that would be possible on most real-world vehicles!) for best efficiency.

Paul

 

[DirtDonk]

We can easily tell from a pic if it's a stock tank or not. There aren't really any aftermarket tanks that are made like a stock one, except for a "stock" replacement.
We call ours a "13.5 gallon" replacement, but I've seen the same ones listed as different sizes from different places. Guess it depends on who you talk to sometimes.

Put up a quick pic in your garage and we can let you know what to expect.
But I'm guessing that your pump location is at least part of the issue.
No way to tell without either moving the pump, or opening up the tank to see if anything is wrong inside.

Paul

 

[Allen_69]

Now that we know it's an electrical pump. I'd try a test, get a piece of flat stock and lower the pump mount a couple of inches and see if you can get more fuel out of the tank.