Mr Gasket 42S Fuel Pump

Introduction: Evaluating the Performance Icon

The Mr Gasket 42S has become an iconic electric fuel pump over the years, known for its reliable performance in a range of demanding applications. This legendary pump has powered everything from hot rods to race cars, making it a favorite among performance enthusiasts. However, with many fuel pump options now available, is the 42S still a smart choice? This comprehensive buying guide takes an in-depth look at the pump’s specs, features, installation, and performance to help you decide.

Key Specs: Flow Rate, Pressure, and Compatibility

First, let’s examine some key specifications for the Mr Gasket 42S to understand its capabilities:

• Flow rate: The 42S is rated to support up to 255 liters per hour or 90 gallons per hour. This high flow allows it to keep pace even with modified high-output engines.
• Pressure: This pump can reliably deliver 4-7 PSI of fuel pressure. The exact pressure depends on voltage and other factors. This is sufficient for carbureted systems.
• Compatibility: The 42S is designed for 12V systems and works with gas engines, including forced induction applications. It is not recommended for diesel engines.
• Inlet/Outlet: Inlet and outlet ports are -6AN male flare fittings, making it easy to connect fuel lines securely.

Installation: Mounting and Wiring

Installing the 42S fuel pump is straightforward with proper planning:

• Mounting: The pump can be mounted near the fuel tank using the included mounting bracket. Isolating it from vibration ensures quiet operation.
• Wiring: Powering the 42S requires a 12V+ switched ignition source. It draws around 15A max. Use adequate wire gauge and relays to handle the current.
• Plumbing: Fuel input and output lines must be compatible with the -6AN flare fittings. Use 5/16 or 3/8” ID hose for the short pump-to-filter run.
• Proper installation is key to maximizing pump life and performance. So take your time and follow instructions.

How It Compares: Advantages of Old School Design

The Mr Gasket 42S represents old school design but still has advantages compared to some newer pumps:

• Proven durability under high loads and engine vibration
• Higher flow rate than most compact modern in-tank pumps
• External mounting provides flexibility in plumbing and troubleshooting
• No complex modern electronics to fail

However, it is also larger/heavier than in-tank pumps and requires custom plumbing work. You have to weigh the trade-offs for your particular build.

Where to Buy: Retailers and Pricing

The 42S can be purchased from a variety of retailers that specialize in performance parts:

• Direct from Mr Gasket for around $109
• Summit Racing usually stocks it for approximately $119
• Jegs has it for about $129
• Amazon sells it in the $115-130 range

Shop around for the best shipping rates and pricing. Mr Gasket sometimes offers sales direct through their website.

Real-World Performance: Flow Testing Results

To really understand the capabilities of the 42S, let’s look at some real-world flow test results:

• At open flow it can reach around 103 gallons per hour. This requires 13V to achieve.
• Under operating pressure of 5 PSI, flow is reduced but still reaches 75-80 GPH, depending on voltage.
• With longer discharge lines and fittings, flow drops but remains adequate for engines making 500+ HP.
• Overall the pump backs up its high flow rate reputation with actual performance.

These flow benchmarks demonstrate why the 42S continues to satisfy hardcore enthusiasts.

Troubleshooting Tips: When Things Go Wrong

Even a solid fuel pump like the 42S can still have issues. Here are some troubleshooting tips:

• No fuel flow – Check fuse, wiring, voltage at pump. Faulty ground connection is common cause.
• Low pressure – Ensure voltage is 13+ at pump. Verify no leaks in discharge side. Replace filter.
• Excessive noise – Pump may cavitate if fuel tank is too low or pickup blocked. Or mounting may be loose.
• Pump fails prematurely – Extreme voltage/amp spikes can overload components leading to early failure.

Taking the time to properly diagnose problems can help get your 42S pumping again.

Keeping Your 42S Alive: Maintenance Tips

With periodic maintenance, the 42S can log many years of reliable service:

• Use a fuel filter downstream to capture particles. Change it regularly.
• Check supply line and tank pickup for obstructions or debris.
• Verify electrical connections are clean and tight. Add dielectric grease.
• Consider a pump voltage stabilizer to prevent over-voltage damage.
• Mount securely to prevent driveline vibration transmitting to pump.
• Check pump periodically for leaks indicating worn seals or gaskets.

A well-maintained 42S should have a long service life powering your performance vehicle.

Conclusion: Still a Strong Player

The Mr Gasket 42S fuel pump clearly remains a viable option for anyone looking to upgrade their fuel delivery system. With a long history of dependable power in demanding applications, it’s a proven performer. While not quite as sophisticated as modern in-tank pumps, its simpler design also provides durability. For the right application, the 42S is still a great choice. Just take the time to properly install and maintain it, and this old school fuel pump will likely outlast your vehicle.