Fuel Tank Install by PO, extra hose with no connection (1 Viewer)

Romer

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I have a Northwest Metal Products 22 Gal fuel tank that was installed in the rear and it is the only tank as the normal fuel tank was removed to add storage space under the passenger seat.

I noticed a small stain on my garage floor several times and a fuel smell after driving. I thought maybe a hose was loose

Looking at it, there is the Fuel fill line and the vent going from the tank to the fuel nozzle. There is also the main fuel line from the tank to the engine bay.

I installed an auxiliary tank on my 80 series and there is another hose I did no0t have on that setup

This one goes from the tank and is bolted to the top of the tube and is not connected to anything. There is fuel residue (stains) coming from the open end of this hose and it is definitely the cause of the fuel spill on my garage and the fuel smell

What is the purpose of this hose? I am tempted to cap it.

I didn't have this on the one I installed into my 80

Fuel 1.jpg
Feul 2.jpg
 

Romer

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To orient on the first pic, I am looking up at the qtr panel and you can see the discoloration at the end of the hose like it was spraying. That just doesn't seem right. A fuel system should be under pressure not with an open hose

I noticed the smell even after running up to the store and back on a cool day, that's about a 4 mile drive roundtrip
 

Romer

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Like you said about vapor, wondering if this is a hookup for a carbon/vapor filter? A shop installed this for the PO and I can't see them leaving it unconnected. I intend on capping it, but would be interested in hearing if someone has other inputs? Like I need to get a vapor filter
 
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Cap/plug on the vent seems reasonable if there's already a vent connected at the fuel fill and the fuel cap is vented. Might be a problem with a full tank in off-camber situation, though maybe no worse than before. To use a charcoal canister I think the Holley EFI kit would need to support it - manifold vacuum port on intake and ECM programming to drive a CCP solenoid. I don't think it does based on a quick search.
 

Romer

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Cap/plug on the vent seems reasonable if there's already a vent connected at the fuel fill and the fuel cap is vented. Might be a problem with a full tank in off-camber situation, though maybe no worse than before. To use a charcoal canister I think the Holley EFI kit would need to support it - manifold vacuum port on intake and ECM programming to drive a CCP solenoid. I don't think it does based on a quick search.

Thanks for the reply and the research. I appreciate it
 
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Emissions. Fuel / vapour separator. My best guess. Other side of separator would go to charcoal canister I think.
 

Romer

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Thanks for all your help. I capped it with a brass fitting. The line was full of fuel so didn't seem like a vapor line to me. I'll see if I notice anything different
 
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Before Downey started manufacturing the rear fuel cell, we sold the NWMP tanks. As I recall they had a plastic fitting on the top wall that a return line hooked up to. I always thought their plastic fittings were on the frail side of life!!!! I'm thinking your top plastic fitting is cracked.
 

Romer

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Before Downey started manufacturing the rear fuel cell, we sold the NWMP tanks. As I recall they had a plastic fitting on the top wall that a return line hooked up to. I always thought their plastic fittings were on the frail side of life!!!! I'm thinking your top plastic fitting is cracked.

Jim, why do you say that? It's a hose coming from the top of the tank to no where. bolted to the top of the tub with no connection, mounted higher than the top of the tank. The line had fuel in it when I took it off the bracket to cap it. Ahh nothing like lying on your back and getting a face full of gas.

If it was cracked, wouldn't it be leaking at the top of the tank?
 

Romer

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I must not understand where it's leaking from?????

Leak may be the wrong word. There was a hose that was not connected to anything, the end was open. The fuel was coming out of the end of the hose. The hose was bolted to the tub above the top of the tank so Gravity wouldn't let it pour out, but under pressure, fuel would travel up the tube and flow into free air. The picture shows the hose, the open end and the fuel residual on the tub. It would then drip leaving a small puddle on my garage floor. The puddle is small, but I am sure it loses fuel while driving as well
 
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My guess is some type of return line. Because it is above the tank but leaks your fuel system must be sealed otherwise. When your garage heats up during the day and the gas expands it's coming out this line. If you remove the gas cap and blow compressed air thru it I bet you will hear it bubble in the tank. Just capping might create a vapor lock or at the very least prevent the pump from feeding fuel to engine because of the vacuum created. Installing a check valve that prevent gas to come out but let air in to keep the tank going into a vacuum would prevent this.
 

Romer

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OK, I have the answer to why it is there.

When I had the Multi-port fuel injection installed, they also installed an in tank pump. Reading the instructions it said to ensure the tank is vented, so they added the line bolted up higher than the tank thinking it would just kick vapor out.

They said if the tank isn't vented it could implode.

So this tank has one of the older style caps (Filler tube cap), not the kind on the newer cruisers that screw in for a tight seal. I am thinking that implosion shouldn't be an issue and I should leave it caped.

Thoughts?
 
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For fuel to leak out that vent above the tank the gas cap would have to be holding it's seal. The gas is slowly warming during the day. If the gas was a tight seal it should be able to vent the tank before it forced gas out that vent. Pumping gas to the engine it's possible for the tank to go into a vacuum. If you want to test it. extend that hose and put a vacuum gauge on it. If it doesn't go into a vacuum your venting the tank from the gas cap or somewhere else. But because it does force above the tank I won't assume the gas cap is vented. Toyota did away with vented gas cap caps over forty years ago. That was well before the cap were screw in type.
 

Romer

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Thanks. Read a post somewhere where a Charcoal canister was added outputting into a filter and then open at the top. I'll keep digging, but capping it might not be the best, but should be ok for short trips
 

Romer

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I have a 22 Gal tank in the rear and a 350, so will have to come up with something different. I will address this after I take care of suspension.
 

Gumby

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You can put a check valve or a roll over valve in it that will let air in but not let air out and then put a vented cap from an early, non-charcoal canister 40 on it. The vented cap will allow fumes to be pushed out when the fuel heats up on a warm day. It sound like that's what might be happening with your vent hose. A charcoal canister does the same thing but allows the fumes to be burnt at cruising speeds rather than releasing raw hydrocarbons into the air.
 

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