Fuel Line question Ford 640 134cc engine

[ltng7679]

I've need to replace metal fuel line and am looking to reroute it due to lousy access. I stripped the treads to the tank valve by not being careful enough starting the tread. luckily I have a new fuel shutoff valve. I was looking to replace the old rusty line with mainly rubber hose that I'd route back toward the battery under the tank and then out along the carburetor air intake hose to the carburetor I was looking for the fittings size and types that goe into the valve and carb. It looks like 1/4" flare tube but the 7/16" nut seems to have 24 threads / inch which seems odd. Can I get any premade tubes with the right fittings from an auto parts store that I can cut and thread into each fitting and then put hose between the two? I hate to spend the money on a new tube that is bent and exact just to cut it up.

Thanks

 

[Hobo,NC]

I've need to replace metal fuel line and am looking to reroute it due to lousy access. I stripped the treads to the tank valve by not being careful enough starting the tread. luckily I have a new fuel shutoff valve. I was looking to replace the old rusty line with mainly rubber hose that I'd route back toward the battery under the tank and then out along the carburetor air intake hose to the carburetor I was looking for the fittings size and types that goe into the valve and carb. It looks like 1/4" flare tube but the 7/16" nut seems to have 24 threads / inch which seems odd. Can I get any premade tubes with the right fittings from an auto parts store that I can cut and thread into each fitting and then put hose between the two? I hate to spend the money on a new tube that is bent and exact just to cut it up.

Thanks

One routed to the front in this post fuel line Yes your assumptions on size is correct (I think without looking).
Just buy a length of line from the parts store and a cheap HF double flair kit and roll your own. Get a longer line use it to practice on life will be good.



AI Overview




A standard \(1/4"\) brake line primarily utilizes a \(7/16"-24\) inverted flare fitting (thread size). These fittings are commonly used in pairs with double-flared or bubble-flared steel or copper-nickel lines to create a reliable, high-pressure sea

 

[ltng7679]

Thanks for the advice - off to NAPA. If I can't make it work I can always order the replacement part.

 

[Lynn Patrick]

I usually just buy a 32" (minimum) brake line from the parts house & bend it to fit. I have a double flare tool, but find it easier to let the parts store do it, then I use my (cheap) HF tubing bender to make it fit. I also then take the opportunity to cut it & install a 1/4 turn valve so I don't have to disturb the often leaky tank valve.

 

[sotxbill]

Rubber eventually cracks and leaks,,, and then the tractor burns to the ground.

 

[Ozlander]

Rubber eventually cracks and leaks,,, and then the tractor burns to the ground.

Not if you use hose approved for gasoline.

 

[showcrop]

Rubber eventually cracks and leaks,,, and then the tractor burns to the ground.

strange then that every autoparts store stocks and sells a lot of rubber fuel line, and every hot rod you see at a car show has rubber fuel line.

 

[used red MN]

Rubber eventually cracks and leaks,,, and then the tractor burns to the ground.

You are correct to a degree. Installing a rubber hose in the fuel system of a gas tractor does not mean it will burst into a gas fed inferno within the week. You appear to be a “purist” who would not consider deviating from the ideal setup for a machine, that is good and serves you well. Sometimes one has to be a bit flexible and allow those who may not know how to cut, flare and bend tubing to do what serves them best. The cracking and leaking usually starts very slowly and can be detected in plenty of time to take preventive action long before the “burn to the ground” point is reached. Is your tractor with all steel fuel lines ahead of the curve in this area, absolutely. Keep in mind many today’s vehicles have plastic gas lines between the tank and the engine that often is pressurized to 40 psi and they also have plastic gas tanks all DOT approved.

 

[showcrop]

A copper fuel line is much less durable than rubber, and should never be used. A steel line without an OEM rubber section is also more susceptible to cracking from vibration and is less durable than rubber.

 

[Btzj02]

The last rubber fuel line I bought had a caution in the package stating something to the effect: "Not to be used in an enclosed area". I am assuming that may mean that an enclosed "heated" area may be a problem. All my small engine equipment uses rubber fuel lines with no problems! For my tractors I do make my own fuel lines from steel but I create an extra loop in the line to create an expansion joint for flexibility.

 

[Eman85]

All rubber fuel lines are not the same, there are ratings for them which are usually ignored due to price.

 

[ltng7679]

Here's my update on my question. I did run a combination of metal brake line and rubber fuel line. I made a right angle bend on the one entering the carb (Zeith aftermarket) and ran it in toward the back of the machine against the air intake manifold stopping it just in front of the location of the oil filled air filter. Connected the rubber hose and ran it up in front of the battery and through the hole in the aft metal frame of the fuel tank. There it connected to a line I ran from the tank. Although it works, I do seem to be getting some vapor lock issues when the machine is standing still idling. It works fine when moving, but the long horizontal runs seem to make it hard for the air gas to bubble up into the tank. I might try to put a constant angle into my design of rubber and metal, but can also just buy the premade all metal replacement line I see in the store of this website.

 

[Tony Jacobs]

Here's my update on my question. I did run a combination of metal brake line and rubber fuel line. I made a right angle bend on the one entering the carb (Zeith aftermarket) and ran it in toward the back of the machine against the air intake manifold stopping it just in front of the location of the oil filled air filter. Connected the rubber hose and ran it up in front of the battery and through the hole in the aft metal frame of the fuel tank. There it connected to a line I ran from the tank. Although it works, I do seem to be getting some vapor lock issues when the machine is standing still idling. It works fine when moving, but the long horizontal runs seem to make it hard for the air gas to bubble up into the tank. I might try to put a constant angle into my design of rubber and metal, but can also just buy the premade all metal replacement line I see in the store of this website.

You would be smarter and time well spent just to install a reproduction original style line and be done with it . You will never stop the vapor lock problems especially with todays gas that boils sooner than the better gas of days gone bye . Ford designed a vertical line for a reason and it was never a problem for 70/80 years all the horizontal Cobb jobs will never replace the factory design .

 

[used red MN]

Although it works, I do seem to be getting some vapor lock issues when the machine is standing still idling.

Is the outdoor temp over 85F, and the machine has been just been worked really hard and is idling slow? If it is not meeting all the criteria in that sentence you’re not experiencing vapor lock, there is some other malfunction. What is the symptom that is encountered that you claim to be vapor lock?

 

[showcrop]

The OP had nothing to do with avoiding the dreaded "internet invented vapor lock". I have bought two OEM fuel lines over the years and never had a problem.

 

[Btzj02]

You would be smarter and time well spent just to install a reproduction original style line and be done with it . You will never stop the vapor lock problems especially with todays gas that boils sooner than the better gas of days gone bye . Ford designed a vertical line for a reason and it was never a problem for 70/80 years all the horizontal Cobb jobs will never replace the factory design .

Actually todays fuels vaporize, (boil), at a higher temperature, (boil later not sooner), due to the fact that the Read Vapor Pressure, (RVP), in todays gasoline is lower than RVP of years gone by. If the comment was to discourage the use of Ethanol in gasoline it may be interesting to know that ethanol does not lower the initial boiling point of gasoline either. Gasoline has a large boiling point range and the initial boiling point is the first temperature where gasoline starts to boil.

 

[Tony Jacobs]

Actually todays fuels vaporize, (boil), at a higher temperature, (boil later not sooner), due to the fact that the Read Vapor Pressure, (RVP), in todays gasoline is lower than RVP of years gone by. If the comment was to discourage the use of Ethanol in gasoline it may be interesting to know that ethanol does not lower the initial boiling point of gasoline either. Gasoline has a large boiling point range and the initial boiling point is the first temperature where gasoline starts to boil.

Well actually it was only to encourage the use of the proper fuel line designed for the tractor by the designers who built the tractor that’s all . Today’s fuel is garbage and it gets worse every year and causes more problems now than ever before . I have seen the fuel go from the old Pink Sunoco 260 fuel to garbage of today that needs to be in a high pressure fuel injection system just to run and evaporate as fast as you burn it . I have oil engineering experience so I understand exactly what you are saying and I know there isnt anything we can do about it so I dont bother beating a dead horse complaining about the fuel . Boiling gas was a problem when these tractors were new and the fuel line was designed the way it was because of that and because of the fuel tank being mounted above the engine with no fuel pump . Gravity feed fuel system doesn’t work on a horizontal line but all of these so called experts think they can route the fuel line better than the engineers who developed the tractors 70/80 years ago and make it better which it never does . Thanks Tony

 

[showcrop]

Actually todays fuels vaporize, (boil), at a higher temperature, (boil later not sooner), due to the fact that the Read Vapor Pressure, (RVP), in todays gasoline is lower than RVP of years gone by. If the comment was to discourage the use of Ethanol in gasoline it may be interesting to know that ethanol does not lower the initial boiling point of gasoline either. Gasoline has a large boiling point range and the initial boiling point is the first temperature where gasoline starts to boil.

I recently read different. I don't recall where but it explained that the different components change things up more than you will get from just the RVP, because though the RVP is lower, the ethanol will evaporate separately before the gas.

 

[Eman85]

Not getting in the chemistry bit but I know with racers that run E85 is the pump gives you E70 or so you can attain 85% by evaporating the gasoline by leaving the can open or bubbling it with low pressure air.
This is where the small engine problems with e10 or 15 come from. The gas evaporates leaving behind ethanol and the ethanol contains the moisture it picked up from the atmosphere.

 

[Btzj02]

The Chemistry: All of the components of gasoline have their own boiling points. The Initial boiling point is determined by the lightest component of gasoline, which is usually forms of propane and butane. Final boiling point may be in the range of #1 fuel oil. Ethanol and water also have defined boiling points. If gasoline mixture begins to boil it is true that what is boiled off is never a pure one component or another it is always a mixture of components. In an oil refinery the height of the fractionation tower dictates how pure a component may be. The higher the tower the better or more pure the product. A tractor gas tank full of an ethanol blend will not boil off just the hydrocarbon or just the ethanol. The vapor and the liquid left behind are both mixtures of all the components in the tank. Ethanol will mix with both a hydrocarbon and water but, it prefers water over the hydrocarbon. If you have a moisture/water problem it can cause the ethanol to drop out of the gasoline but as long as the concentration of ethanol in the water is greater than 54% or 100 proof it will still burn in the engine. So if you have a 10 gallon tank at 10% ethanol it would be able to absorb just under 1/2 gallon of water and he tractor will still run. Incidentally because ethanol likes water better than hydrocarbon refiners cannot use underground pipelines to ship ethanol blend products. Pipelines are the low point in any system and they are all saturated with water. For the same reason if you drive by a tank farm you can spot the ethanol blended gasoline tanks because they have a geodesic dome covering. All hydrocarbon tanks have a low point bleed to periodically drain water that separates to the bottom of every tank. With all that said. Water ingress is the enemy of all areas of the tractor filled with hydrocarbon. There are other reasons to not use ethanol blend in small engines and older equipment but ethanol does not cause a water problem. Water does. If I believed that I had a water problem in my gas tank the first thing I would do is add alcohol to the tank. After all the Ford shop manual states to use alcohol to dry out a fuel tank after cleaning. Don't blame the ethanol, blame the water!