Fuel 1985 GT Fuel Line Diagram

DienstXIV · Apr 17, 2025

Hi Everyone,

I have a 1985 Mustang GT with a 670 CFM Street Avenger Holly carb. Does anyone have a fuel line diagram for a 1985?

With the warm weather I have been smelling fuel pretty strongly. The whole car just smells like gasoline. I checked for leaks but couldn't find any. I noticed that near the front drivers side of the engine where I believe the fuel pump is there is a plugged line coming out of the pump. I am wondering if this is for some sort of fuel return line going back to the tank that I need to reconnect. Also when I remove the fuel cap there is a lot of pressure that is released. I understand my carb is too big but don't want to spend the money on a smaller one if I don't have to. I am thinking maybe the fuel smell is because the pressure is too high, but then wouldn't it leak somewhere? There is also a charcoal canister but it looks like it's disconnected. It would be nice to know how this fuel system all works together, I cannot find anything for carbureted Fox Body Mustangs.

Any help would be much appreciated!

Cheers,
Alex

AeroCoupe · Apr 17, 2025

This thread may help

Fuel Thread 'Fuel line routing question..'

Mar 23, 2024

Changing over from single exhaust to dual on my 83 mustang..
Had to change over the brake lines and wondering if the fuel lines route differently at the fuel tank with the Fuel Injected cars??
While setting the rear tailpipe on the pass side, it seems like the fuel lines are a bit close??
Tried to find some pics online but nothing came up that I could use..
Fuel tanks seem to have the same basic sizing and the hole in the " high " side seems to be the same in all of the fox bodies
Any help here..... TY

@85GTStangGuy - can you provide some guidance?

85GTStangGuy · Apr 18, 2025

AeroCoupe said:
@85GTStangGuy - can you provide some guidance?

Happy to...

DienstXIV said:
Does anyone have a fuel line diagram for a 1985?

Yea, there's one in my exploded view manual. I'll find it and post it up here in the next day or so.

DienstXIV said:
I noticed that near the front drivers side of the engine where I believe the fuel pump is there is a plugged line coming out of the pump. I am wondering if this is for some sort of fuel return line going back to the tank that I need to reconnect.

Yea, there should be a return line coming out of the stock fuel pump, going back to the tank. It's purpose is to vent fuel pump vapors back to the tank. That may be the cause of your smell issue.

I can get more info on it's routing if you need. It's probably gonna be on the above-referenced fuel line diagram.

DienstXIV said:
Also when I remove the fuel cap there is a lot of pressure that is released.

Not sure about that.... but somethings not right if the pressure is excessive.

DienstXIV said:
I am thinking maybe the fuel smell is because the pressure is too high, but then wouldn't it leak somewhere?

I doubt the fuel pump pressure is too high. That mechanical pump should put out about 8.5 psi.... not sure how it'd put out more.... less, sure.... but probably not more than it's designed to, imo.

DienstXIV said:
There is also a charcoal canister but it looks like it's disconnected. It would be nice to know how this fuel system all works together, I cannot find anything for carbureted Fox Body Mustangs.

That charcoal canister would normally be a solution (or part of one) for a gas smell. But the stock carb has bowl vents that it's connected to.... I don't see any vents on that Avenger carb, so I don't know how it'd hook up.

And read that thread @AeroCoupe linked. It's not exactly what you asked about, but it does have some pertinent info in it.

DienstXIV · Apr 19, 2025

85GTStangGuy said:
Happy to...

Yea, there's one in my exploded view manual. I'll find it and post it up here in the next day or so.

Yea, there should be a return line coming out of the stock fuel pump, going back to the tank. It's purpose is to vent fuel pump vapors back to the tank. That may be the cause of your smell issue.

I can get more info on it's routing if you need. It's probably gonna be on the above-referenced fuel line diagram.

Not sure about that.... but somethings not right if the pressure is excessive.

I doubt the fuel pump pressure is too high. That mechanical pump should put out about 8.5 psi.... not sure how it'd put out more.... less, sure.... but probably not more than it's designed to, imo.

That charcoal canister would normally be a solution (or part of one) for a gas smell. But the stock carb has bowl vents that it's connected to.... I don't see any vents on that Avenger carb, so I don't know how it'd hook up.

And read that thread @AeroCoupe linked. It's not exactly what you asked about, but it does have some pertinent info in it.

Thanks for the info! My charcoal canister is still in the engine bay but not connected to anything. Does the 1985 GT have a valve for the charcoal canister? There is an electrical connector in the area of the charcoal canister. What kind of line was used to go from the charcoal canister to the tank? Rubber or metal?

I feel like I need a fuel return line. I cannot find one on my car, it should be a metal one next to the feed right? I noticed that the front part of the tank is a little wet.

AeroCoupe · Apr 19, 2025

I’m gonna guess the vent on top of the tank is not working. This is a picture of the fuel tank in my 1993 when I reworked the fuel system.

The vent is the top right white object. This connects to the charcoal tank. So as the pressure builds up in the tank it vents into the charcoal canister. If the solenoid is closed then it vents to atmosphere via the canister but if the somebodies open the vapors are burned in the motor.

DienstXIV · Apr 19, 2025

Thanks for the picture! I feel like reconnecting the vent to the charcoal canister will help with the smell and maybe add some mpgs. How does the vent line run under the car?

AeroCoupe · Apr 20, 2025

Clueless there. You will have to wait on 85GTStangGuy to post up some pics or diagrams as the layout is different than my 1993 Coupe.

85GTStangGuy · May 15, 2025

DienstXIV said:
I feel like reconnecting the vent to the charcoal canister will help with the smell and maybe add some mpgs. How does the vent line run under the car?

@DienstXIV - You still working on this?

If it's operating properly, it should definitely help with the smell issue. Wouldn't expect any gas mileage change tho.

For the canister vent line routing, look at the 5th pic down on the linked post....

Fuel Post in thread 'Fuel line routing question..'

Apr 2, 2024

limp said:
I wish I had a stock 85 close by I could crawl under...

Hang on.... I know a guy!

@limp - I got some answers for ya....

limp said:
Problem seems to be fuel lines only, From what I can see they need to be routed differently to work,, The loop in the exhaust that goes over the rear axle hits them.....

Viewing from the back of the car (and keeping in mind, at the time, I was only able to see forward of the rearend about a foot or so due to my point of view), the fuel lines run down the passenger side of the driveshaft tunnel, along the edge where the tunnel meets the...

DienstXIV · Jul 12, 2025

Hi everyone,

So I ordered new fuel lines for my GT from Classic Tube. Once I get them I am going to drop the tank and install a new tank vent valve and the lines, as well as make and weld on some new fuel tank strap brackets. One is all rusted out and held up by zip ties right now.

While I am waiting for that, I want to hook up the EVAP system. I believe in my car there is a solenoid valve that allows fuel vapor to enter my intake when the car is on or in certain conditions? There isn't one in my car but LMR says there is one for my car. I found a connector in my engine bay that will connect to the solenoid valve I got off of LMR. Only problem is, I am not getting power to the connector. I checked when the car is off and when the car is on and warmed up. It could just be corroded, does anyone know how to clean really small female electrical connectors? Pictures of connector attached. The electric lines go to the main engine harness and mostly everything else works so why wouldn't this work? Is a 1985 engine computer smart enough to only open the valve under certain conditions?

What would happen if I just connect the vacuum lines directly to the carb vacuum port without any valve? It wouldn't be ideal but probably better than not having it hooked up at all right?

Thanks I'm advance for the help!

Cheers,
Alex

Fuel 1985 GT Fuel Line Diagram

DienstXIV

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AeroCoupe

lube between the nut and the face. I know my lubes

Fuel Thread 'Fuel line routing question..'

85GTStangGuy

DienstXIV

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AeroCoupe

lube between the nut and the face. I know my lubes

DienstXIV

Member

AeroCoupe

lube between the nut and the face. I know my lubes

85GTStangGuy

Fuel Post in thread 'Fuel line routing question..'

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Fuel 1985 GT Fuel Line Diagram

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lube between the nut and the face. I know my lubes

Fuel Thread 'Fuel line routing question..'

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lube between the nut and the face. I know my lubes

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lube between the nut and the face. I know my lubes

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