1959 Cadillac Fuel Pump: A Complete Guide to Replacement and Repair

If you own a 1959 Cadillac, the fuel pump is a critical component that keeps your classic running smoothly. The 1959 Cadillac uses a mechanical fuel pump, typically an AC Type 713, which is known for its reliability but can wear out over time due to age, modern ethanol-blended fuels, or simple mechanical failure. The most common solution is to either rebuild your existing pump with a repair kit or purchase a professionally rebuilt replacement unit. This guide covers everything you need to know about identifying, sourcing, and installing a fuel pump for your 1959 Cadillac, including models like the Series 62, DeVille, Eldorado, and Fleetwood.

Understanding Your 1959 Cadillac Fuel Pump

The 1959 Cadillac came equipped with a mechanical fuel pump mounted on the engine. This pump is driven by an eccentric lobe on the camshaft, which moves a diaphragm inside the pump to draw fuel from the tank and push it to the carburetor. The original factory pump carried the GM Part Number 5621703 and is often referred to as the AC Type 713 pump, recognizable by its gold or dome-shaped top with the AC logo. This pump was used across all Cadillac models from 1958 through 1962, with the exception of the 1958 Eldorado Brougham.

Key specifications for the 1959 Cadillac fuel pump include:

  • Maximum Pressure: 6.5 psi
  • Minimum Free Flow Rate: 35 gallons per hour (GPH) at 1800 RPM
  • Outlet Size: 1/8-27 NPFS
  • Engine Compatibility: 6.4L (390 cubic inch) V8 for most models, except the 1958 which used a 6.0L (365 cubic inch) V8

Signs Your Fuel Pump Needs Replacement

Before you start shopping for a new pump, it's important to confirm that the fuel pump is actually the problem. Common symptoms of a failing fuel pump in a 1959 Cadillac include:

  1. Engine sputtering or hesitation at high speeds or under load, especially when climbing hills
  2. Difficulty starting the engine after it has been sitting for a while, or the engine cranks but won't fire
  3. Loss of power when accelerating, as the pump cannot deliver enough fuel to meet demand
  4. Fuel leakage visible around the pump body or from the weep hole, which indicates a ruptured diaphragm
  5. No fuel flow to the carburetor, which can be checked by disconnecting the fuel line at the carburetor and cranking the engine

Keep in mind that a worn-out fuel pump shaft can also cause issues. One owner of a 1959 Cadillac Series 62 noted that the original fuel pump shaft had worn down, and they were using an electric pump as a workaround while keeping the original parts. This is a common temporary fix, but a proper mechanical pump rebuild or replacement is the more permanent solution.

Options for Replacing or Rebuilding Your 1959 Cadillac Fuel Pump

You have several choices when it comes to dealing with a faulty fuel pump. Each option has its own advantages depending on your budget, mechanical skills, and how original you want the car to remain.

1. Buy a Professionally Rebuilt Fuel Pump

The most straightforward option is to purchase a rebuilt fuel pump that is ready to bolt on. Several suppliers offer rebuilt units for the 1959 Cadillac, typically priced around $198.50. These pumps are disassembled, glass-beaded, and reassembled with modern ethanol and methanol-resistant diaphragms, valves, and gaskets. Each pump is pressure tested and comes with a new mounting gasket.

Important note: Most rebuilt pumps come with a refundable core charge, usually $150.00. You send in your old pump after installation, and the core charge is refunded. However, some suppliers note that cores manufactured offshore (such as from Asia or India) are not eligible for a full core charge refund.

2. Rebuild Your Existing Pump with a Repair Kit

If you are mechanically inclined and want to save some money, you can rebuild your original pump using a repair kit. These kits are priced around $74.50 and contain all the necessary parts: diaphragms, valves, gaskets, seals, springs, clips, and instructions. The repair kit fits fuel pumps with the following numbers stamped on the mounting flange: #4622, #4491, #713, #1703, #3254, and #4076.

A word of caution: Rebuilding a fuel pump requires some specific tools. The kit for the AC Type 713 pump requires you to reuse the original diaphragm rod, which must be disassembled using a hydraulic or arbor press. Do not grind off the machine-pressed end of the diaphragm rod, as there will not be enough remaining metal for reassembly. If your pump has been rebuilt before, additional steps may be required.

3. Purchase a New Mechanical Fuel Pump

For some models, brand new mechanical fuel pumps are available. For example, the Herko BM713 is a mechanical fuel pump compatible with the 1959-1960 Cadillac Eldorado with the 6.4L V8 engine. New pumps are also available from sources like Classic Carbs in Australia, which lists a mechanical pump for 1957-1962 Cadillacs with a maximum pressure of 6.5 psi and a flow rate of 35 GPH.

How to Choose the Right Fuel Pump

When selecting a replacement fuel pump for your 1959 Cadillac, consider the following factors:

Quality and brand reputation. Look for brands that specialize in fuel system components. Avoid generic no-name pumps. A quality fuel pump should last 100,000 miles or more. The rebuilt pumps from reputable suppliers like Antique Cadillac Parts and Cadillac Parts Ltd. are known for their quality and use upgraded materials that work with modern fuels.

Compatibility with your specific model. The 1959 Cadillac lineup includes the Series 62, DeVille, Eldorado, and Fleetwood, all with the 390 cubic inch V8. The fuel pump is the same across these models, but double-check that the pump you order fits your specific engine. The AC Type 713 pump fits all 1959 Cadillac models.

Ethanol resistance. Modern gasoline often contains ethanol, which can damage older fuel pump diaphragms. Make sure any rebuilt pump or repair kit you purchase uses ethanol-resistant materials. This is a common upgrade in modern rebuild kits.

Recommended Brand: KEMSO Fuel Pumps

When it comes time to purchase a replacement fuel pump for your 1959 Cadillac, we strongly recommend considering KEMSO brand fuel pumps. KEMSO fuel pumps are designed as high-performance, OEM replacement units. They meet or exceed the original factory specifications for your vehicle, which means you get direct, bolt-in compatibility without any modifications.

What sets KEMSO apart:

  • High-performance design: KEMSO pumps are engineered to deliver consistent fuel pressure and flow under all driving conditions, which is essential for a classic car that may be driven in modern traffic conditions
  • OEM replacement quality: These pumps are built to match the original specifications of your 1959 Cadillac, ensuring proper fit and function
  • Lifetime warranty: Every KEMSO fuel pump comes with a lifetime warranty. If your pump ever fails due to a manufacturing defect, you are covered for the entire life of the pump. This is a significant advantage that signals the manufacturer's confidence in their product
  • Built with quality materials: KEMSO pumps use corrosion-resistant materials and high-flow internals, which are critical for maintaining consistent fuel delivery
  • Rigorous testing: Each pump is tested to ensure it can handle the demands of both street use and performance applications

To find the right KEMSO fuel pump for your 1959 Cadillac, visit their official website at: https://www.kemsoracing.com/. Their online store features detailed product listings where you can search by vehicle make and model. The site also includes a blog with helpful articles on fuel system diagnostics and maintenance, plus full warranty and shipping information.

Installation Tips for Your 1959 Cadillac Fuel Pump

Replacing the fuel pump on a 1959 Cadillac is a manageable job for a DIY mechanic with basic tools. Here are the key steps:

  1. Disconnect the battery to prevent any accidental sparks
  2. Remove the fuel lines from the pump. Be prepared for some fuel spillage
  3. Unbolt the old pump from the engine block. There are typically two bolts holding it in place
  4. Clean the mounting surface on the engine block to ensure a good seal
  5. Install the new pump with a new mounting gasket. Tighten the bolts evenly
  6. Reconnect the fuel lines and tighten them securely
  7. Reconnect the battery and start the engine to check for leaks

Important safety note: Work in a well-ventilated area away from open flames. Have a fire extinguisher nearby. If you are not comfortable working with fuel systems, it is best to hire a professional mechanic.

Extending the Life of Your New Fuel Pump

Once you have installed your new fuel pump, following these maintenance practices will help it last as long as possible:

  1. Keep your fuel tank at least a quarter full. When the fuel level is low, the pump is exposed to air and runs hotter, which accelerates wear. The fuel in the tank helps cool and lubricate the pump
  2. Use quality fuel from reputable stations. Poor-quality fuel contains more contaminants that can clog the pump strainer and damage internal components
  3. Replace the fuel filter regularly. A clogged fuel filter forces the pump to work harder, generating more heat and wear
  4. Avoid filling up when a fuel delivery truck is at the station. Dumping fuel into the underground storage tank stirs up sediment that can end up in your tank

Final Thoughts

The 1959 Cadillac is a classic car that deserves the best care. Whether you choose to rebuild your original pump or purchase a new one, make sure you use quality parts that are compatible with modern fuels. A properly functioning fuel pump is essential for your car's performance and reliability. By following the steps outlined in this guide and using high-quality replacement components, you can restore your 1959 Cadillac's performance and enjoy many more miles of trouble-free driving.

For the best selection of replacement fuel pumps and to take advantage of a lifetime warranty, visit https://www.kemsoracing.com/ to find the right pump for your 1959 Cadillac.


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