Katerina Swanson
Converting an older Johnson dual fuel line to a single fuel line is a topic that has been widely discussed on boating forums and antique engine forums. While some people suggest that it is a simple modification, others argue that it is not worth the effort and recommend sticking with the original two-line pressure tank system. The conversion process may involve adapting the hose, blocking the pressure side, and leaving the cap loose for ventilation. Some people have shared their experiences and offered advice on the necessary modifications, such as drilling, tapping, and fabrication. Additionally, there are custom bypass covers available that enable the use of modern fuel pumps and single-line gas tanks with older dual fuel line outboards.
Characteristics and Values Table
| Characteristics | Values |
|---|---|
| Engine Type | Johnson 10 Hp QD series |
| Year | 1958 to 1963 |
| Conversion Method | Using a custom bypass cover and fuel pump |
| Difficulty | Simple, does not require much mechanical knowledge |
| Materials Needed | Custom bypass cover, modern fuel pump, standard 1/4" auto fuel line |
| Cost | Custom bypass cover: $20; Pressure tanks: $20 |
| Alternative Methods | Using epoxy or rubber plug, drilling into the crankcase |
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What You'll Learn
The process of converting a Johnson dual fuel line to a single fuel line
Firstly, it is necessary to understand the differences between the dual fuel line and single fuel line systems. The dual fuel line system in Johnson outboards involves a pressurized two-line tank. Pressure from the engine is transmitted through one line to the fuel tank, which then sends fuel through the other line to the carburetor. On the other hand, the single fuel line system utilizes a pulse-activated fuel pump, where pressure pulses from the revolution of the crankcase activate a diaphragm in the fuel pump, controlling the flow of fuel with a one-way valve.
To begin the conversion process, you will need to gather the necessary tools and materials, which may include a fuel pump, hoses, fittings, and an adapter or bypass cover. Some people choose to fabricate their own adapter plates, but custom-made options are also available for purchase. The specific parts required may vary depending on the model of your Johnson outboard.
Next, you will need to remove the old dual fuel line system. This involves disconnecting the fuel lines, carburetor, and linkage, as well as removing the intake manifold and reed plate. It is important to be careful during this process to avoid damaging any components that may still be in good condition.
Once the old system has been removed, you can start installing the new single fuel line system. This typically involves adapting the hose to work with the new fuel pump and ensuring that the cap is loose to provide proper ventilation. If you are using an adapter or bypass cover, follow the manufacturer's instructions for proper installation.
Finally, you will need to test the new single fuel line system to ensure it is functioning correctly. Pay close attention to the fuel flow and make any necessary adjustments to ensure the engine is running smoothly. It is also important to regularly maintain your fuel system to prevent any potential issues and ensure the safety of your boat.
Converting a Johnson dual fuel line to a single fuel line can be a straightforward process, but it requires careful planning and execution. By following the steps outlined above and consulting additional resources as needed, you can successfully perform this conversion and enjoy the benefits of a more modern fuel system.
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The benefits of using a fuel pump system
A fuel pump system is an essential part of a boat's motor. It helps move the fuel from the tank to the fuel injection system, enabling the boat to run smoothly and efficiently. The pump draws fuel from the tank and delivers it to the engine, where it is mixed with air by the carburetor or fuel injector before entering the boat motor. Modern outboard motors are extremely powerful and fuel-efficient, and a well-maintained fuel pump system is key to their longevity and performance.
There are two main types of fuel pumps: mechanical and electric. Mechanical fuel pumps were the standard method of delivering gas to the engine, using a rod or lever to suck the gas from the tanks. Electric fuel pumps, on the other hand, use electrical power to move gas from the tank and offer greater versatility in flow rates and pressure settings. Electric pumps are particularly useful when high-fuel pressures are required, such as with turbochargers and fuel injection.
The benefits of a well-functioning fuel pump system are significant. Firstly, it ensures the boat has enough power and speed. Secondly, it helps maintain fuel efficiency, saving money and reducing environmental impact. Additionally, regular inspections and maintenance of the fuel pump system can help prolong the life of the boat's engine, as fuel pump issues can lead to other engine components failing. For example, a broken fuel diaphragm or a blockage in the fuel lines can cause the engine to starve and die due to a lack of fuel.
Furthermore, a fuel pump system can help prevent issues caused by fuel contamination. Fuel contamination can occur due to corrosion, moisture, and debris in the fuel tank, which can then affect multiple components, including the fuel pump and engine. By regularly checking and maintaining the fuel pump system, boat owners can identify and address these issues early on, saving time and money on repairs. Overall, a well-maintained fuel pump system is crucial for the safe and efficient operation of a boat, providing peace of mind for boat owners and enthusiasts alike.
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The drawbacks of using a fuel pump system
While there is some information available on converting a Johnson two-line fuel tank to a single fuel line, there is limited information on the drawbacks of using a fuel pump system. However, here is some general information on the disadvantages of an electric fuel pump system:
Electric fuel pumps can fail, causing the engine to not get fuel and resulting in a stalled vehicle. They can also leak, which can be dangerous and costly. Electric fuel pumps are also more expensive than mechanical fuel pumps and require an expert to replace them.
Some boat owners prefer to keep their Johnson two-line fuel tanks as they are reliable and have worked well for over 50 years with simple maintenance. The conversion to a single fuel line is not easy and requires drilling, tapping, and fabrication. It is also important to be careful when using a tank with a fuel pump, as it may overpressure the carb float. Additionally, conversion pumps can produce too much pressure for the carb, while the original design dribbles gas to the carb with no pressure.
Overall, while it is possible to convert a Johnson two-line fuel tank to a single fuel line with a fuel pump system, there are some drawbacks and challenges to consider. It may be preferable to keep the original two-line pressure tank system, which is reliable and easy to maintain.
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The cost of converting to a single fuel line
For those who want to buy a new tank, the cost of a single-line plastic tank is relatively affordable and can be purchased for a low price. In addition, a fuel pump may need to be installed, which can range in price depending on the type and brand chosen. It is important to note that the fuel pump is necessary to ensure fuel can reach the motor.
On the other hand, those who prefer to modify their existing dual-line tank can expect to incur costs for the required parts and adaptations. For example, adapting the hose and leaving the cap loose to function as a vent is a simple modification that can be made. Additionally, blocking the pressure side of the hose and drilling a hole in the cap is another option, as mentioned by a user who performed this conversion.
It is worth noting that some people have expressed a preference for the pressure tank system, citing its reliability and ease of finding replacement tanks and rebuild kits. Rebuild kits for the fuel tank, which include gaskets, o-rings, and hoses, can be found for around $20.
When it comes to the motor itself, there are different approaches to converting it to a single fuel line. One method involves using a simple bracket to adapt the motor to work with a newer pulse-style fuel pump. This can be achieved by replacing one of the bypass covers with an adapter plate, which can be purchased or fabricated by those with the necessary skills and equipment. Another approach is to install a small electric pump and use a regular tank, which requires plugging the vacuum port on the block and running a separate hose to the carburetor.
Overall, the cost of converting to a single fuel line can vary depending on the specific choices made during the conversion process. It is recommended to carefully consider the available options and seek advice from knowledgeable sources before proceeding with any modifications.
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$162.99
The reliability of Johnson dual fuel lines
Johnson dual fuel lines are reliable and have worked well for over 50 years. However, some people prefer to convert them to single fuel lines for various reasons. One reason is to avoid having two separate fuel systems, which can be inconvenient and take up space. Another reason is that the dual fuel line system can be prone to coking, which can cause fuel valves and lines to become plugged.
Coking occurs when oil bakes at high temperatures, and it can coat check-valve internal surfaces and fuel lines, restricting the movement of valve parts. Engineers can take steps to mitigate the risk of coking during the design stage, such as installing a recirculating liquid system or moving fuel lines away from the turbine casing to reduce their exposure to high temperatures.
Converting a Johnson dual fuel line to a single fuel line can be a simple process that does not require much mechanical knowledge or skill. One common method is to use a custom bypass cover, which allows the use of modern fuel pumps and single-line gas tanks with older dual fuel line outboards. These custom bypass covers are available for purchase online. Another method is to drill and tap a fitting into the intake transfer port for a pulse fitting to drive a pump.
Some people prefer to keep the original dual fuel line system, as it is reliable and easy to find replacement parts. Tank rebuild kits are readily available, and the tanks themselves can be found on eBay, yard sales, and other sources. Additionally, the conversion process can be complex for some models, requiring drilling, tapping, and fabrication.
In summary, Johnson dual fuel lines are reliable and have a long history of successful operation. While some people choose to convert them to single fuel lines for convenience or to avoid coking issues, others prefer to keep the original system due to its reliability and the availability of replacement parts. Ultimately, the decision to convert depends on individual preferences and the specific circumstances of the boat owner.
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Frequently asked questions
You can convert a Johnson dual fuel line to a single fuel line by plugging one side with a vacuum line plug or epoxy. You can also use a fuel pump to draw fuel out of the pressure tank by adapting the hose and leaving the cap loose for a vent.
Converting to a single fuel line can simplify your fuel system and make it easier to swap motors and use the same fuel line. It can also be a more modern system that uses pulse-activated fuel pumps.
Converting to a single fuel line may require alterations to your intake manifold and pressure tank check valve system. It may also be more expensive and difficult to find parts for the single fuel line system.
Yes, you can use a fuel pump with a dual fuel line tank by adapting the hose and leaving the cap loose for a vent. However, you may need to disable the one-way valve in the tank.
You can buy parts for the conversion online from websites such as eBay, iboats, Smokstak, and Vintageoutboard. You can also find used tanks and hoses at yard sales or through online communities such as aomci.org.
