Any tricks for finding a leak in fuel line ?

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I had the same problem. Only spot I ever found where my fuel line might have been getting a little air is where the rubber line attaches to the metal line at frame rail. OEM line had a crimped clamp on it. It was a little loose. Repairing that made no difference.
Later models have the fuel filter positioned vertically down near the fuel pump and a thicker base gasket under the carb. Filter fills and fuel in it stays a little cooler down there. I made those changes to my 67 so I could run todays fuel. Once the non ethanol "real gas" became available I run it in everything here that has a carburetor. I haven't had to replace a line or primer bulb on the weed wacker since. Real gas costs more but well worth it to end all the fuel delivery issues I had for years.
 
I thought we were talking about filling a gas tank with 15 psi of air pressure, no where near the same as the fuel line at 15 psi. Yes it is the same psi but no where near the same force.
 
RedFish said:
I had the same problem. Only spot I ever found where my fuel line might have been getting a little air is where the rubber line attaches to the metal line at frame rail. OEM line had a crimped clamp on it. It was a little loose. Repairing that made no difference.
Later models have the fuel filter positioned vertically down near the fuel pump and a thicker base gasket under the carb. Filter fills and fuel in it stays a little cooler down there. I made those changes to my 67 so I could run todays fuel. Once the non ethanol "real gas" became available I run it in everything here that has a carburetor. I haven't had to replace a line or primer bulb on the weed wacker since. Real gas costs more but well worth it to end all the fuel delivery issues I had for years.
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The ethanol can be removed from the fuel, put two gallons in plastic 5 gallon water bottle. Add water slowly to the 2 gallons and the ethanol will separate from the gas (over saturation) siphon off the fuel at the top. In the long run it comes out the same price (gas companies have this figured out too). But in a pinch this can be done.
 
That's how we used to check for water in fuel, add alcohol and the water and alcohol will separate.
 
Dang lots of advice here thanks I appreciate it everyone . Oh and I don’t think it’s the fuel pump because I had just replaced that . But yeah somewhere in between the fuel pump and the tank I guess .. it could even be the connection where the filter is it looks kinda janky but I don’t think it’d be bubbling that badly but what do I know haha
 
Diego53 said:
Dang lots of advice here thanks I appreciate it everyone . Oh and I don’t think it’s the fuel pump because I had just replaced that . But yeah somewhere in between the fuel pump and the tank I guess .. it could even be the connection where the filter is it looks kinda janky but I don’t think it’d be bubbling that badly but what do I know haha
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Think of it this way, fuel pump sucks the fuel forward, and hole will let in air. Check the short rubber hose at the tank to the steel fuel line, hard to check the steel line for a crack or rust hole the reason I suggested a LITTLE pressure, it will force any fuel out (need a helper for this). But if it has a hole being low it would form a puddle. If no puddle that lead back up to that short hose (I replaced a lot of those) if you change it don’t forget the small ground connector. All bubbles form before the pump. IF they are ok the line IN the tank is bad (I’ve seen them rust thru)
 
That's a nice flange. A small return line to the tank would help vent that boiled gas out the line while keeping enough pressure to fill the carb, especially a low pressure Carter/brock.
 
If it was me, I would follow the drip.
 
So I threw a new fuel line on and still bubbling .. I figured the line might be getting too hot and boiling the gas because there’s a point where it gets real close to the exhaust manifold so I bought some heat insulation shroud stuff from Orielly’s, put it on where I thought it’d be getting too hot and took it for a drive. Same bubbling now I’m going back to thinking there’s a leak somewhere:(
 
did you try my soap spray method? Put a few psi of air in at the carb inlet side and start spraying that soapy solution on the entire line and look for bubbles. Worst that can happen is you get a clean fuel line.....
 
Hope you will forgive the qualifications needed for a newbie here, outside air comes from wherever vacuum pulls it when the fuel line is plugged.

Before the loss of days of data, I had suggested a vacuum gauge check at the tank pick up line...

New here, but been in the trenches professionally for 5 decades...
 
I'm with @Ceedawg /post 32.
If you put gearclamps on that line, then you need two per side with the screws staggered 180*, else the pump will suck air there. And because it is higher than the fuel level in the tank, it does not leak liquid. And at atmospheric pressure (engine off) it doesn't leak anything at all.
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One thing nobody mentioned is that when HOT fuel under pressure passes over a sharp point, it tends to form bubbles there. IDK what the bubbles are, I just see them forming. Same happens when the hot fuel passes from a high-pressure area to a low pressure area, like into the float bowl.
To help stop that, I put the filter at the back of the car, and run a one-piece hardline from the low-pressure pump to the carb, with no anchor points to the hot engine, which runs at 207*F . After that I just run the engine at WOT most of the time, so there is never any fuel-pressure to speak of...... lol.
Oh, I almost forgot, my fuel line is right in the path of the air coming thru the rad, pulled in by the 7-blade, high attack-angle, all-steel fan, so it sits in a constant bath of about 180* air. Once the hood is closed, that is about the coolest temp you will find under there.
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BTW-1
I have been running 87E10, which is "up to 10%" alcohol, in my combo since 1999 with ZERO problems. I mean nil/nada/nucht/nietski, and zilch.
All this yakitty-yak about alcoholized fuels being a problem is, IMO, just that.

BTW-2
Gasoline is made up of many, many components.
The lightest compounds in the fuel are said to boil at 95*F, at STP (Standard Temperature and Pressure). At 4.5 psi inside the hot fuel line, this condition does not exist. But once the fuel is in the bowl, sitting on an engine that is over 200*F, literally a hot-plate, you can bet that those lighter components are very eager to go anywhere but down into the engine.
When you shut your hot engine off; within seconds those compounds are evaporating. As the float-bowl empties, the fuel-valve opens and the pressure between the pump and bowl drops to zero and the fuel in that line begins to boil. Pretty soon all the VOCs (Volatile Organic Compounds) are boiled off, and all you have left are the heavier components, some of which require over 400* to break down.
Next morning you come out, and crank and crank and crank, because your engine cannot create the heat to ignite those heavy compounds. Finally your pump primes and pushes some fresh fuel with the lighter VOCs, up into the bowls, and Shazzam! she lites up.
Granted; premium fuel does not have those same light VOCs in it, so this is less of a problem. But Premium has other stuff in it, that slows its burn rate, to help prevent detonation. I call it slowgaz, and I don't want no stinking slowgaz in my engine . So I made 87E10 work. Cuz you know; gasohol has oxygen in it, lots of oxygen. Ok not lots, up to 35% by weight IIRC, but neither does the atmosphere, being less than 20% oxygen by weight....... at sealevel. So it's relative. The other 80% is mostly nitrogen, which really serves no useful function as a fuel. Yet there it is, free/no extra charge, thanks be to the Ancient of Days.
Think of it this way; By running 10% ethanol, I just eliminated the compressing of a portion of the useless nitrogen; Hooray free horsepower. But more importantly I injected liquid oxygen at the rate of 35% per pound of that gasohol.
And people call me crazy for burning it!
And they say I can't go as fast as I do go in the Eighth.
And they say it's impossible to get 32mpg out of any 360.
To which I have a standard reply; Just cuz your engine cannot do it, does not mean it cannot be done.
But I digress, lol.
 
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67Dart273 said:
You do NOT want to put any 15 psi into the tank. Disconnect the line, plug one end, and pressurize it. Actually just replace it if you know it's the line
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Man, if you don't replace known original/ used items like that, You WILL have problems. I could never figure out my 63 Dart gt... /6. I could push air ( my own hot air) from the pump input line and hear it bubble in the tank. Pulled the tank, cleaned it, everything. Except that damn hose... so YESSIR! And my 74 gave me FITS till I changed the hard line. Would idle, run, raise some cain, then just when IT wanted to, would die. Sometimes after half hour or more , sometimes enough for me to get out if the neighborhood. I bent them, and the brake lines by hand for my 66, got the inline tube line for the 74. And upgraded to the larger while there.
 
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AJ/FormS said:
I'm with @Ceedawg /post 32.
If you put gearclamps on that line, then you need two per side with the screws staggered 180*, else the pump will suck air there. And because it is higher than the fuel level in the tank, it does not leak liquid. And at atmospheric pressure (engine off) it doesn't leak anything at all.
========================
One thing nobody mentioned is that when HOT fuel under pressure passes over a sharp point, it tends to form bubbles there. IDK what the bubbles are, I just see them forming. Same happens when the hot fuel passes from a high-pressure area to a low pressure area, like into the float bowl.
To help stop that, I put the filter at the back of the car, and run a one-piece hardline from the low-pressure pump to the carb, with no anchor points to the hot engine, which runs at 207*F . After that I just run the engine at WOT most of the time, so there is never any fuel-pressure to speak of...... lol.
Oh, I almost forgot, my fuel line is right in the path of the air coming thru the rad, pulled in by the 7-blade, high attack-angle, all-steel fan, so it sits in a constant bath of about 180* air. Once the hood is closed, that is about the coolest temp you will find under there.
========================
BTW-1
I have been running 87E10, which is "up to 10%" alcohol, in my combo since 1999 with ZERO problems. I mean nil/nada/nucht/nietski, and zilch.
All this yakitty-yak about alcoholized fuels being a problem is, IMO, just that.

BTW-2
Gasoline is made up of many, many components.
The lightest compounds in the fuel are said to boil at 95*F, at STP (Standard Temperature and Pressure). At 4.5 psi inside the hot fuel line, this condition does not exist. But once the fuel is in the bowl, sitting on an engine that is over 200*F, literally a hot-plate, you can bet that those lighter components are very eager to go anywhere but down into the engine.
When you shut your hot engine off; within seconds those compounds are evaporating. As the float-bowl empties, the fuel-valve opens and the pressure between the pump and bowl drops to zero and the fuel in that line begins to boil. Pretty soon all the VOCs (Volatile Organic Compounds) are boiled off, and all you have left are the heavier components, some of which require over 400* to break down.
Next morning you come out, and crank and crank and crank, because your engine cannot create the heat to ignite those heavy compounds. Finally your pump primes and pushes some fresh fuel with the lighter VOCs, up into the bowls, and Shazzam! she lites up.
Granted; premium fuel does not have those same light VOCs in it, so this is less of a problem. But Premium has other stuff in it, that slows its burn rate, to help prevent detonation. I call it slowgaz, and I don't want no stinking slowgaz in my engine . So I made 87E10 work. Cuz you know; gasohol has oxygen in it, lots of oxygen. Ok not lots, up to 35% by weight IIRC, but neither does the atmosphere, being less than 20% oxygen by weight....... at sealevel. So it's relative. The other 80% is mostly nitrogen, which really serves no useful function as a fuel. Yet there it is, free/no extra charge, thanks be to the Ancient of Days.
Think of it this way; By running 10% ethanol, I just eliminated the compressing of a portion of the useless nitrogen; Hooray free horsepower. But more importantly I injected liquid oxygen at the rate of 35% per pound of that gasohol.
And people call me crazy for burning it!
And they say I can't go as fast as I do go in the Eighth.
And they say it's impossible to get 32mpg out of any 360.
To which I have a standard reply; Just cuz your engine cannot do it, does not mean it cannot be done.
But I digress, lol.
Click to expand...
I’m writing this all down. I wanna know HOW you got that mpg, always thought premium would evaporate fast. We used to run cam 2 purple cell would be empty next race, on a wim I had some blue so we ran it and next race it was still there in the tank, it didn’t evaporate! The other racers were buying 55 gallon drums every month, one drum of blue lasted us all racing season. Cam 2 guys loved selling all that gas I bet! I’ll send a pm
 
If I just blow into the line will that somehow Not make enough pressure to identify a leak with the soapy water method? I don’t have a compressor or bike pump or anything to use
 
RustyRatRod said:
If it was me, I would follow the drip.
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****! You beat me to it Rusty! Every gas leak I've ever seen leaves a tell-tale black streak! Get under the car and eye ball it. You can see pretty much all the gas line under there so as Rusty said, follow the trail!!
 
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