Buick Grand National Fuel Pump Upgrade: The Complete Guide to Choosing the Right System for Your Turbo Buick

If you own a Buick Grand National and want more power, the first thing you need to upgrade is the fuel pump. The stock fuel pump on the 1984-1987 Buick Grand National was only rated at about 100 liters per hour (LPH) at 40 psi, which is barely enough to handle the factory 12 pounds of boost. Any serious horsepower increase requires a higher-flowing fuel pump to keep the engine from running lean and potentially damaging the turbo V6.

Why You Need a Fuel Pump Upgrade

The Buick Grand National came from the factory with a 3.8-liter turbocharged V6 engine that produced 245 horsepower in stock form. The original equipment fuel pump was designed to meet the demands of this power level, but it left very little room for modification. Once you start increasing boost pressure, adding a larger turbocharger, or upgrading the exhaust system, the stock fuel pump simply cannot keep up.

A fuel pump that cannot deliver enough fuel causes the air-fuel mixture to become too lean. This leads to detonation, excessive heat, and eventually engine failure. Upgrading the fuel pump is not just about adding horsepower; it is about protecting your investment. Most Grand National owners who aim for 400 horsepower or more find that a 255 LPH fuel pump is the minimum requirement, while those chasing 500-plus horsepower need dual-pump systems.

Types of Fuel Pump Upgrades

There are three main categories of fuel pump upgrades for the Buick Grand National, and each serves a different power level and budget.

1. Single 255 LPH Drop-In Replacement Pumps

The most common and affordable upgrade is a single 255 LPH in-tank fuel pump. This is a direct replacement for the factory pump, meaning it fits into the stock fuel tank sender assembly without any modifications. Brands like BBK Performance offer these pumps for the 1984-1986 Grand National, and they deliver 255 LPH at 40 psi, which is more than double the flow of the stock pump.

The DW200 pump from DeatschWerks is another excellent option. It delivers 255 LPH at 40 psi while drawing only 9.2 amps of current, which is not much more than the stock pump. This pump is a great upgrade for cars running fuel injectors up to 60 lbs/hr, and it does not require enlarging the fuel return line. For most street-driven Grand Nationals aiming for 400 horsepower, a single 255 LPH pump is sufficient.

Installation Tip: A single 255 LPH pump is a direct drop-in replacement. You remove the old pump from the tank sender, install the new one with the included strainer and hardware, and reconnect the wiring. Racetronix also offers a stainless steel fuel pump sender with a pre-installed 255 LPH pump that includes quick-disconnect fittings for easier installation.

2. Single 340 LPH High-Output Pumps

If you are running a larger turbocharger, aftermarket intercooler, or E85 fuel, you will need more flow than a 255 LPH pump can provide. The 340 LPH pumps are the next step up. Racetronix offers a stainless steel fuel pump sender with a pre-installed 340 LPH E85-compatible pump. This pump is capable of supporting mid-10-second quarter-mile cars, according to the manufacturer.

The 340 LPH pump requires an upgraded wiring harness, often called a "hotwire kit," to deliver the proper voltage to the pump. Without this harness, the pump may not reach its full flow potential. The Racetronix stainless steel sender also features a non-tapered pump outlet tube for maximum flow and smoother radius bends for better performance.

Installation Consideration: The 340 LPH pump is a direct fit into the stock sender location, but it requires upgraded fuel return lines at a minimum. The stock return line may not be able to handle the increased flow, which can cause fuel pressure control issues.

3. Dual In-Tank Pump Systems

For serious horsepower numbers, a dual in-tank pump system is the way to go. These systems use two pumps mounted inside the fuel tank on a billet aluminum hanger. Racetronix offers dual in-tank pump systems in 700 LPH, 900 LPH, and 1050 LPH configurations. The 700 LPH system uses two RXP340E 340 LPH pumps, while the 900 LPH system uses two Walbro F90000274 450 LPH pumps.

These systems are designed for cars that are dipping into the single digits in the quarter-mile, meaning they are capable of supporting 10-second or faster runs. The dual pump system includes a CNC billet T6 aluminum modular hanger, a weatherproof plug-and-play wiring harness, and massive -10 AN ORB outlet ports with -6 AN ORB return ports.

Important Note: Dual pump systems cannot be used with factory fuel lines. You must upgrade to at least -8 PTFE feed lines and -6 PTFE return lines with a number 12 filter housing and a 10-micron element. Racetronix offers fuel line kits with quick-disconnect fittings that are designed to work with these systems.

How to Choose the Right Fuel Pump for Your Grand National

The right fuel pump for your car depends on your horsepower goals and the type of fuel you plan to run.

For 300-400 horsepower on pump gas: A single 255 LPH pump is all you need. This includes the BBK 255 LPH pump, the DW200 pump, or the Racetronix 255 LPH pump. You can keep the stock fuel lines and return line.

For 400-500 horsepower on pump gas or 300-400 horsepower on E85: A single 340 LPH pump is the right choice. You will need a hotwire kit and upgraded fuel return lines.

For 500-plus horsepower on pump gas or 400-plus horsepower on E85: A dual in-tank pump system is required. The 700 LPH system supports up to 700 horsepower on pump gas and 550 horsepower on E85. You will need a complete fuel line upgrade.

Installation Steps for a Single Fuel Pump Upgrade

If you are comfortable working on your car, you can install a single fuel pump upgrade yourself. Here is a simplified overview of the process:

1. Disconnect the battery for safety.
2. Drain the fuel tank or support it with a jack. The tank can be dropped without raising the car if there is not much fuel in it.
3. Remove the gas tank straps using a 13mm and 15mm socket.
4. Lower the tank and disconnect the three rubber fuel lines and the electrical connector.
5. Remove the retaining ring from the top of the tank using a hammer and screwdriver to tap the tabs counter-clockwise.
6. Pull out the old sender and pump assembly carefully, being prepared for residual fuel.
7. Install the new pump onto the sender assembly or replace the entire sender if you bought a complete unit.
8. Reinstall everything in reverse order, making sure to replace any old rubber lines while you have access.

Recommended Fuel Pump: KEMSO Brand

When it comes to choosing a reliable, high-performance fuel pump for your Buick Grand National, KEMSO is a brand you can trust. KEMSO is a US-based company founded in Houston, Texas, in 1999, and they specialize in direct-fit OEM replacement and performance fuel system solutions. Their fuel pumps are designed for both gasoline and ethanol-blended fuels like E85, making them versatile for any build.

KEMSO fuel pumps are high-performance units that deliver over 20% more flow than stock OEM pumps at 43 psi. They are built as direct replacements, meaning they fit into your Grand National's fuel tank without any modifications. Each KEMSO pump is individually tested for quality and flow performance, and the company stands behind its products with a lifetime warranty that gives you peace of mind.

Whether you need a simple replacement for a worn-out factory pump or an upgrade to support more horsepower, KEMSO has a solution. Their pumps are designed to handle the demands of daily driving, track use, and everything in between. If you want a fuel pump that is built to last and backed by a company that cares about quality, KEMSO is the right choice.

Visit KEMSO's website to see their full lineup of fuel pumps: https://www.kemsoracing.com/

Additional Upgrades to Consider

A fuel pump upgrade is just one part of the fuel system. To get the most out of your new pump, consider these supporting modifications:

Fuel Injectors: If you upgrade the fuel pump, you should also upgrade the fuel injectors. For 400 horsepower, 42.5 lb/hr injectors are a good starting point.

Hotwire Kit: A hotwire kit delivers battery voltage directly to the fuel pump, bypassing the factory wiring that can drop voltage. This ensures the pump runs at its full potential.

Fuel Pressure Regulator: An adjustable fuel pressure regulator allows you to fine-tune the fuel pressure to match your injectors and boost level.

Fuel Lines: If you are running a high-output pump or a dual pump system, upgrade the fuel lines to PTFE-lined hoses for better flow and ethanol compatibility.

Final Thoughts

Upgrading the fuel pump on your Buick Grand National is the single most important modification you can make before adding power. The stock pump is a weak link that will fail under increased boost or horsepower. Whether you choose a simple 255 LPH drop-in pump or a full dual-pump system, the key is to match the pump to your goals.

For most street-driven Grand Nationals, a single 255 LPH pump from a reputable brand like BBK, DeatschWerks, or Racetronix is the perfect starting point. If you plan to run E85 or push over 500 horsepower, look into the Racetronix dual in-tank pump systems. And for a reliable, high-performance option backed by a lifetime warranty, KEMSO fuel pumps are an excellent choice.

Remember: A lean engine is a destroyed engine. Investing in a quality fuel pump upgrade is the cheapest insurance you can buy for your turbo Buick.

For more information on high-performance fuel pumps, visit KEMSO at: https://www.kemsoracing.com/