Regan Brown
The rubber fuel line diameters for a CJ7 are a popular topic of discussion among car enthusiasts. Many people are unsure about the correct diameter for the return, with suggestions ranging from 5/16” to 3/8”. Some people are also unsure about whether they can reuse their old rubber fuel lines or if they need to install special fittings to avoid blowing fuel.
| Characteristics | Values |
|---|---|
| Fuel line size | 8 mm or 5/16" |
| Supply | 3/8" |
| Return | 5/16" |
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What You'll Learn
What diameter should I use for the return?
The recommended fuel line size for most fuel injection systems is 8mm or 5/16". However, some people recommend a 3/8" supply and a 5/16" return.
If you are installing a 4.0l EFI engine, you will need to use EFI-rated fuel lines. You can attach an EFI-rated fuel line and EFI fitting to the short metal tube (supply) on your CJ7 gas tank.
It is also important to consider the pressure of the fuel system. If you are using a high-pressure system, you may need to install special fittings to avoid blowing fuel across your exhaust.
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Can I safely run EFI-rated rubber lines from the front to back?
Yes, you can safely run EFI-rated rubber lines from the front to back of your CJ7. However, it is important to note that you cannot reuse your old rubber fuel lines as the 4.0L EFI is a high-pressure system.
The fuel line size you should use for your CJ7 is 8mm or 5/16". You can use a 3/8" supply, but this may be overkill and cause friction loss.
When it comes to the return, a 5/16" diameter is recommended. You can splice into the original 5/16" steel line a fuel filter and inline pump using fuel injection rubber hose just above the fuel tank. In the engine bay, you can use the same rubber hose to connect the steel line where it ends to the injection system.
Some people prefer to use stainless steel lines or hardlines, but this is not required as long as the hose is protected. If you are concerned about pressure, you may want to consider installing hardliners with special fittings to avoid blowing fuel across your exhaust.
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Should I use stainless lines?
The fuel line size for most fuel injection systems is 8 mm or 5/16". However, if you're using a 4.0L EFI engine, you cannot reuse your old rubber fuel lines.
So, should you use stainless lines? Well, it depends on your application. If you're running a high-pressure fuel injection system, then stainless lines may be a better option than rubber lines. Stainless lines are more durable and can withstand higher pressures. They are also less likely to leak or rupture, which could be dangerous.
However, there are a few things to consider before making the switch. First, stainless lines can be more expensive than rubber lines. Second, they may be more difficult to install, especially if you're not familiar with the process. Finally, stainless lines can be more rigid than rubber lines, which could make them more susceptible to vibration and movement.
If you're unsure whether to use stainless or rubber lines, it's always best to consult a professional. They can help you assess your specific application and make a recommendation based on your needs.
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Will the hardlines hold the pressure-rated fuel?
The fuel line size for most fuel injection systems is 8 mm or 5/16". However, it is not clear whether the hardlines will hold the pressure-rated fuel. One user on a forum asks whether they need to install a special fitting to avoid blowing fuel across their exhaust. Another user says that they cannot reuse their old rubber fuel lines, as the 4.0L EFI is a high-pressure system.
One user recommends a 3/8" supply and a 5/16" return. Another user spliced into the original 5/16" steel line a fuel filter and inline pump using fuel injection rubber hose just above the fuel tank. They also used the same rubber hose to connect the steel line to the injection system in the engine bay.
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What diameter should I run for the supply?
The fuel line size for most fuel injection systems is 8 mm or 5/16". However, some recommend a 3/8" supply line to avoid friction loss.
If you are installing EFI-rated fuel lines, you will not be able to reuse your old rubber fuel lines. You will need to attach an EFI-rated fuel line and EFI fitting onto the short metal tube (supply) with a standard slip fitting.
It is also important to consider the pressure of the fuel lines. If you install hardliners, you may need to install a special fitting to avoid blowing fuel across your exhaust.
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Frequently asked questions
5/16” is the most common diameter for fuel lines on fuel injection systems.
Yes, but you may want to consider plumbing stainless lines instead.
3/8" is recommended, although this may be overkill for some applications.
Yes, but you will need to use a standard slip fitting.
