fuel "issue"

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BuffDragon
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fuel "issue"

Post by BuffDragon » Fri Aug 21, 2009 9:18 am

actually have 2 questions, though I might already know the answer to the first

1: on my aux tank, the gauge only registers half full, when I know the tank was topped off at the pump. loose ground not giving a good reading perhaps?

2: the bronco sits in the garage and just reeks of gas, though it doesnt leave any puddles on the floor. been trying to read up on vent lines and such, but its fairly confusing. and my wife thinks we might blow up.... 8O


thanks yall!
we call it, "Thriller"

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Stan
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Post by Stan » Fri Aug 21, 2009 9:52 am

What year is your Bronco? The " newer years " have a charchol canister and fuel tank vent lines.
The inaccurate fuel gauge can be several things.
Bad or out of adjustment dash voltage regulator, bent float arm , bad or missing float , hmm maybe some more.
Start with the easiest - try adjusting the instrument cluster voltage regulator. Do a search here - this has been previously discussed. If that doesn't help drop the tank and take out the " fuel pickup tube and sending unit" The aux tank isn't too difficult to remove.
Stan
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Post by DirtDonk » Fri Aug 21, 2009 10:34 am

Before you adjust the IVR though, is the gauge reading normally with the main tank? When I first got my '71, both tanks read low. Had to pull the sending units and tweak the float arms manually until they read correctly.

On the fumes, see if you can determine where they're strongest with a walk-around. They could be coming from a leaky vent or fill or overflow hose. Or they could be coming from the little plastic tank in the side of the cabin just behind the driver's seat. Not all Broncos had one, but if yours does, there's a good chance the seam has split and needs re-sealing. All of ours did.

Then there's always the old worn out gas caps that could do it.

And on a side note, regarding the fuel gauge, how many gallons can you fill the tanks with? Side tanks varied from about 5 to 7 I think, and rears varied from 11 to 14 if I remember.

Paul
'71 Bronco - 302 4v
3.5" WH/Skyjacker Lift
33 x 11.50 x15 Thornbirds on 15x7 Enkei's
Kayline soft top
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bronko69er
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Post by bronko69er » Fri Aug 21, 2009 11:04 am

DirtDonk wrote:
And on a side note, regarding the fuel gauge, how many gallons can you fill the tanks with? Side tanks varied from about 5 to 7 I think, and rears varied from 11 to 14 if I remember.

Paul
Just FYI, my 74's side tank is 8 gal, my 69 is 11 gal.

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Post by DirtDonk » Fri Aug 21, 2009 11:25 am

Hah! Yeah, my '71's side tank is 7 on a good day (5 more often than not) and the rear main was 11.
Even if they do hang down, you just gotta' love those 23 gallon replacements! No more stressing over whether the next gas station will be closed at midnight on Friday in the Sierras.

Paul
'71 Bronco - 302 4v
3.5" WH/Skyjacker Lift
33 x 11.50 x15 Thornbirds on 15x7 Enkei's
Kayline soft top
Hanson bumpers
Dual batteries, Large 1G alt.

WWW.WILDHORSES4X4.COM :mrgreen:

BuffDragon
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Post by BuffDragon » Fri Aug 21, 2009 12:39 pm

duh.....yeah, I guess more info would help, huh
:fedup:


she's a 74 half cab. I havent seen any little bottles in the cab and have been around it pretty good when I was putting harnesses in it. (no, I didnt drill a hole in something ;) )

main tank reads right (I'm 'assuming' as it showed full when I over flowed it on accident....)


at the end of the day, I'm not sure I really care that much about the aux reading 100% as I'm not taking road trips in it. however, I'd prefer everything to work right on her.

another question (yeah, I'm full of questions, amongst other things....)

can I just plumb it somehow so the two tanks equalize into each other, creating one large one? or would that not be as simple as it sounds?
we call it, "Thriller"

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Post by bronko69er » Fri Aug 21, 2009 1:35 pm

Not quite as simple as it sounds.

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Viperwolf1
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Post by Viperwolf1 » Fri Aug 21, 2009 4:35 pm

A '74 should have a condensation tank in the bedside right behind the driver's seat. That tank allows the tanks to breath liquid and gas vapors into it through a vent on each fuel tank. Any liquid that condenses in the plastic tank is returned to the main tank through another small vent line at the top. Vapors that remain are then vented to the charcoal canister behind the right front wheel. With all the parts in place and working you will not smell gas in the garage.
Phil

'74 Sport, '89 5.0 HO SEFI, C4, 33's, 4.10 gears, and a few Hickey parts

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Post by BuffDragon » Fri Aug 21, 2009 9:17 pm

so, I think I found it, looking from underneath the rig.
little plastic looking lines going in thru a grommet. looks like 2 from the back, and maybe 2 from the front? one line is just hanging there, like if something were to run out of it, it'd run out on the ground.
problem is, I'm assuming a bulkhead would block access to this tank. right?
and my bulkhead is perm in now, as the whole tub was sprayed with rhino lining. so I cant remove it, without cutting it out, basically.

now what? I'm guessing those lines cant be plugged....
we call it, "Thriller"

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Post by Viperwolf1 » Fri Aug 21, 2009 10:35 pm

2 lines to the rear tank and 1 to the aux tank. The other one should go to the charcoal canister. That one crosses under the body behind a support rail. Maybe its just disconnected.
Phil

'74 Sport, '89 5.0 HO SEFI, C4, 33's, 4.10 gears, and a few Hickey parts

www.alpineclassicbroncos.com

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Post by BuffDragon » Sun Aug 23, 2009 6:37 am

Viperwolf1 wrote:2 lines to the rear tank and 1 to the aux tank. The other one should go to the charcoal canister. That one crosses under the body behind a support rail. Maybe its just disconnected.

looks the 1 line that goes across to the charcoal canister is cut just below the aux tank. further, I cant find a charcoal canister.
also, as I said, since the bulkhead is now rhino lined in to place, I cant get to the first can (evap can?)

so now what? can all those lines be plugged or do they have to be there in order for the system to work properly?
or
can I make something else and hang it under the rig? I guess it'd have to be higher than the top of the tanks, right?

great info guys.....thanks a ton
we call it, "Thriller"

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Stan
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Post by Stan » Sun Aug 23, 2009 7:40 am

I believe the vent line for the aux tank should cross over ABOVE the frame -high next to the body behind a support rail like - Viper said.
The charchol canister for our '76 is mounted on the firewall on the passenger side.
I'm not sure if your bulkhead being Rhino coated is going to make a difference. The '76 has no bulkhead and I've never "seen" the "can" and I don't know how i'd access the vapor can for it if i wanted to -- from the bottom ??
Stan
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Post by BuffDragon » Sun Aug 23, 2009 10:21 am

Stan wrote:I believe the vent line for the aux tank should cross over ABOVE the frame -high next to the body behind a support rail like - Viper said.
The charchol canister for our '76 is mounted on the firewall on the passenger side.
I'm not sure if your bulkhead being Rhino coated is going to make a difference. The '76 has no bulkhead and I've never "seen" the "can" and I don't know how i'd access the vapor can for it if i wanted to -- from the bottom ??
Stan
the vent line is cut. it drops down about 8" from where it exits under the driver side. cant find any other lines it should attach to, so I'm assuming that part is gone.

does all this mess "have" to be there in order for the fuel system to function correctly?
we call it, "Thriller"

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Post by Viperwolf1 » Sun Aug 23, 2009 4:39 pm

You won't be able to park it inside without the fuel smell if it's not all there. If it's just the line to the charcoal canister thats missing just run a new one. If you need a canister you can pick one up in a wrecking yard for almost nothing.
Phil

'74 Sport, '89 5.0 HO SEFI, C4, 33's, 4.10 gears, and a few Hickey parts

www.alpineclassicbroncos.com

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Post by BuffDragon » Sun Aug 23, 2009 7:18 pm

Viperwolf1 wrote:You won't be able to park it inside without the fuel smell if it's not all there. If it's just the line to the charcoal canister thats missing just run a new one. If you need a canister you can pick one up in a wrecking yard for almost nothing.

sounds easy enough.
what about the first can behind the bulkhead?
how do you get to that (if its split, as someone suggested)?
again, the whole tub was sprayed so if there's an access, its glued together now.
we call it, "Thriller"

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Post by Viperwolf1 » Sun Aug 23, 2009 8:11 pm

The tanks are pretty durable when mounted. I'd just leave it for now if you have enough hose underneath to get everything hooked up. If it leaks after that then worry about opening it up.
Phil

'74 Sport, '89 5.0 HO SEFI, C4, 33's, 4.10 gears, and a few Hickey parts

www.alpineclassicbroncos.com

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Post by BuffDragon » Mon Aug 24, 2009 8:22 am

ok, fair enough.
I'll just get a charcoal canister and get it installed!

last question (on this topic)

does it have to be up high (like above the gas tanks) or does it matter?
ie, can I hang it under the rig somewhere?

thanks yall, been a huge help and hopefully get the wife off my ass.....
(not likely)
we call it, "Thriller"

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Post by Viperwolf1 » Mon Aug 24, 2009 10:21 am

The charcoal canister height should not matter because it only should have fumes going into it. Closer to the engine would be good because the engine needs to be able to suck the fumes out of it.
Phil

'74 Sport, '89 5.0 HO SEFI, C4, 33's, 4.10 gears, and a few Hickey parts

www.alpineclassicbroncos.com

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Post by Scodge » Mon Aug 24, 2009 5:09 pm

If you put the canister lower than the tank, it could fill up with fuel if the overflow fills up, assuming you have an overflow. If you don't, I'd make sure the charcoal canister is higher than the gas tank, which shouldn't be too hard, considering that the gas tank is lower than everything but the tires. The hose that vents the charcoal canister should vent into the air cleaner so the fumes get sucked into the engine.
Scott
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Post by Viperwolf1 » Mon Aug 24, 2009 5:37 pm

The '70-'75 charcoal canisters were mounted lower than the tanks. The vapor condensation tank was higher and sent any liquid fuel back to the main tank.
Phil

'74 Sport, '89 5.0 HO SEFI, C4, 33's, 4.10 gears, and a few Hickey parts

www.alpineclassicbroncos.com

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Post by Scodge » Mon Aug 24, 2009 7:25 pm

Still not a good design. If the charcoal canister is the lowest point of the fuel storage system, it can end up holding gas, instead of eliminating fumes. Especially with a home-made system from salvage yard parts. The smartest bet is to put the charcoal canister in the engine compartment just higher than the gas tank, with a length of hose that vents into the air cleaner so the engine burns the fumes.
Scott
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