12/08/2013
The Datsun 240Z, a true icon of automotive history, continues to capture the hearts of enthusiasts worldwide. Its timeless design and exhilarating driving experience are undeniable. However, as these classic machines age, their original fuel systems can become a bottleneck for performance and a source of reliability issues. Upgrading the fuel system is a crucial step for any 240Z owner looking to unlock its full potential, whether for spirited driving, track days, or simply ensuring smooth, dependable operation. This article delves into the common issues with the stock fuel system and explores the recommended upgrades, covering everything from fuel pumps and regulators to carburettors and fuel lines. We'll help you make informed decisions to keep your legendary Z running at its peak.
Understanding the Stock 240Z Fuel System
The original Datsun 240Z was equipped with a robust, albeit somewhat dated, fuel system designed for its era. It typically featured a mechanical fuel pump driven by the camshaft, a simple fuel filter, and twin Hitachi SU-type carburetors. While these components were adequate for the car's original performance targets, they often show their age. Mechanical fuel pumps can lose pressure over time, leading to fuel starvation under load. The original carburetors, while capable of producing a satisfying induction roar, can be finicky to tune and may not flow enough fuel for more potent engine builds. Furthermore, the rubber fuel lines of this era can degrade, becoming brittle and posing a fire risk.
Common Issues with the Original Fuel System:
- Degraded Rubber Fuel Lines: Over decades, rubber components degrade, leading to leaks and potential fire hazards. Replacing these with modern, ethanol-resistant lines is paramount.
- Weak Mechanical Fuel Pump: The original mechanical pump can lose its diaphragm integrity, resulting in insufficient fuel delivery, especially at higher RPMs.
- Carburettor Wear and Tuning Difficulties: Worn jets, needles, and internal seals can make tuning difficult, leading to poor idle, hesitation, and reduced power.
- Fuel Filter Clogging: The original filter may not be adequate for modern fuel formulations or can become easily clogged with debris from an aging fuel tank.
Recommended Fuel System Upgrades for the 240Z
When it comes to upgrading your 240Z's fuel system, the goal is usually to improve reliability, fuel delivery consistency, and performance. Here's a breakdown of the key components and popular upgrade paths.
1. Electric Fuel Pump Conversion
One of the most common and beneficial upgrades is switching from the mechanical fuel pump to an electric fuel pump. Electric pumps offer several advantages:
- Consistent Fuel Pressure: They provide a steady and reliable fuel supply, regardless of engine RPM.
- Easier Installation: While requiring some wiring, they eliminate the need for the camshaft drive mechanism.
- Improved Performance: Many aftermarket electric pumps are designed to flow more fuel, supporting higher horsepower engines.
- Reliability: Modern electric pumps are generally more reliable and have a longer lifespan than their mechanical counterparts.
When selecting an electric fuel pump, consider reputable brands like Holley, Mallory, or Carter. Ensure the pump is rated for the required fuel flow and pressure for your engine's needs. It's also advisable to install a new fuel filter specifically designed for electric pumps and compatible with modern fuels.
2. Fuel Pressure Regulator
If you're upgrading to an electric fuel pump, especially one capable of higher pressures, a fuel pressure regulator becomes essential. This device maintains a constant fuel pressure to the carburetors, preventing over-fuelling and ensuring optimal performance. An adjustable regulator offers the flexibility to fine-tune fuel pressure for different engine configurations.
Table: Fuel Pump and Regulator Considerations
| Component | Stock | Recommended Upgrade | Benefits |
|---|---|---|---|
| Fuel Pump | Mechanical | Electric (e.g., Holley Red/Blue) | Reliability, consistent pressure, higher flow potential |
| Fuel Pressure Regulator | None (integrated in pump) | Adjustable (e.g., Aeromotive, Mallory) | Precise fuel pressure control, prevents flooding |
| Fuel Lines | Rubber | Braided Stainless Steel or High-Quality Rubber (ethanol resistant) | Durability, safety, resistance to fuel degradation |
3. Carburettor Upgrades
While the original Hitachi carburetors can be rebuilt and tuned, many 240Z owners opt for aftermarket carburetors to improve performance and ease of tuning. Popular choices include:
- Weber Carburetors: The iconic Weber DCOE or IDA carburetors are a favourite among enthusiasts. They offer excellent performance, a wide range of tuning capabilities, and that classic motorsport sound. A common setup is a dual Weber 45 DCOE or 40 DCOE setup.
- Mikuni Carburetors: Similar to Webers, Mikuni carburetors (like the PHH series) are also highly regarded for their performance and reliability.
- Modern EFI Systems: For the ultimate in performance, reliability, and drivability, consider a modern Electronic Fuel Injection (EFI) system. While a more significant investment, EFI offers precise fuel control, automatic adjustments for altitude and temperature, and improved fuel economy. Brands like Holley Sniper or FiTech offer complete kits suitable for classic cars.
If sticking with the original carburetors, ensure they are thoroughly cleaned, rebuilt with new gaskets and seals (like the new fuel cap gasket mentioned), and properly tuned. Rebuilding kits are readily available for Hitachi carburetors.
4. Fuel Tank and Sender Unit
As the fuel tank ages, rust and debris can accumulate inside, contaminating the fuel and clogging filters and carburetors. Consider removing and cleaning the fuel tank, or if it's significantly corroded, replacing it with a new or professionally restored unit. While you're at it, checking and potentially replacing the fuel sender unit will ensure your fuel gauge remains accurate.
5. Fuel Lines and Fittings
Replacing the old, potentially brittle rubber fuel lines is a non-negotiable safety upgrade. Opt for braided stainless steel lines or high-quality, ethanol-resistant rubber fuel lines. Ensure all fittings are secure and leak-free. Using the correct AN fittings and adapters will provide a clean and professional installation.
Installation Tips and Considerations
When undertaking fuel system upgrades on your 240Z, safety should be your top priority. Always disconnect the battery before working on the fuel system and ensure the area is well-ventilated. Have a fire extinguisher readily available.
- Wiring: Properly wire the electric fuel pump, using a relay and a suitable fuse. Consider wiring it to come on with the ignition or with an oil pressure safety switch.
- Fuel Pump Mounting: Mount the electric fuel pump securely, preferably in a location that minimizes vibration and noise.
- Fuel Pressure Testing: After installation, always test the fuel pressure at the carburetor inlet to ensure it's within the specified range.
- Leak Checks: Thoroughly check all connections for leaks before starting the engine.
- Carburettor Tuning: If you've upgraded carburetors or rebuilt the originals, proper tuning is essential for optimal performance. This often involves adjusting the idle mixture, idle speed, and potentially jetting.
Frequently Asked Questions
Q1: Do I really need to upgrade my fuel pump on a stock 240Z?
A1: While a stock 240Z might run on its original mechanical pump, it's a component that often fails with age. An electric pump offers significantly better reliability and consistent fuel delivery, especially if you plan on driving the car spiritedly.
Q2: What's the best fuel pressure for a 240Z with Weber carbs?
A2: For most Weber setups on a 240Z, a fuel pressure of around 3 to 3.5 PSI is typically recommended. Always consult the specific recommendations for your chosen carburetor model.
Q3: Can I use modern ethanol fuel with my stock 240Z fuel system?
A3: It is generally not recommended to run modern E10 or higher ethanol fuels through a completely stock 240Z fuel system. Many of the original rubber components are not ethanol-resistant and can degrade quickly. Upgrading to ethanol-resistant fuel lines and potentially a new fuel tank is highly advised if you intend to use modern fuels.
Q4: How much more power can I expect from a Weber carb upgrade?
A4: The power gains from a Weber carb upgrade can vary significantly depending on the specific Weber model, engine condition, and tuning. However, a well-tuned dual Weber setup can typically add anywhere from 10-20 horsepower over a healthy stock setup, along with improved throttle response and a more aggressive sound.
Q5: Is it worth converting to EFI on a 240Z?
A5: For those seeking the ultimate in drivability, fuel efficiency, and performance tuning, an EFI conversion is definitely worth considering. It offers significant advantages over carburettors, but it is a more complex and costly modification. For a purely classic driving experience, a well-maintained carburettor setup is often preferred.
Conclusion
Upgrading the fuel system on your Datsun 240Z is an investment in its performance, reliability, and safety. Whether you opt for a simple electric fuel pump conversion, a full carburetor upgrade, or even a modern EFI system, these modifications will ensure your classic Z car continues to provide years of exhilarating driving pleasure. Always prioritize quality parts, proper installation, and thorough testing to achieve the best results. With the right fuel system, your 240Z will be ready to tackle any road with confidence and power.
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