0391667 Fuel Pump: The Complete Guide to Replacement, Performance, and Reliability

The 0391667 fuel pump is a universal replacement part designed for Johnson and Evinrude outboard motors, specifically fitting 9.9HP and 15HP models produced between 1974 and 1980, and is also compatible with earlier models through a simple conversion. If your outboard is hard to start, stalls at low speeds, or sputters under load, the fuel pump is often the culprit. This guide covers everything you need to know about the 0391667 fuel pump, including symptoms of failure, installation tips, and where to find the best replacement.

What Is the 0391667 Fuel Pump?

The 0391667 is a small square-style fuel pump used on many OMC (Outboard Marine Corporation) outboard motors. It is a direct replacement for original part numbers including 387027, 386979, 386835, 386480, and 388683. This pump is widely recognized as a standard upgrade for earlier Johnson and Evinrude motors because of its improved reliability and ease of maintenance.

Key Features:

  • Universal Fit: Fits most small OMC outboards from 9.9HP to 40HP, with broad application from 1968 through 1987.
  • Simple Design: The pump uses a diaphragm-based mechanism, making it easy to rebuild or replace.
  • Integrated Filter: The 0391667 pump includes a stainless steel filter screen underneath the inlet cover, which catches debris before it reaches the carburetor.

Symptoms of a Failing 0391667 Fuel Pump

A bad fuel pump can cause a range of problems. Here are the most common signs that your 0391667 pump needs attention:

  1. Hard Starting: The engine cranks but struggles to fire up, especially after sitting for a few days.
  2. Stalling at Idle: The motor runs fine at higher speeds but dies when you throttle down to idle.
  3. Loss of Power: The engine feels sluggish during acceleration or under load.
  4. Fuel Leaks: You may notice fuel dripping from the pump housing or the fuel line connections.
  5. No Fuel Flow: If the pump diaphragm is torn or the check valves are stuck, no fuel will reach the carburetor.

Compatible Models for the 0391667 Fuel Pump

The 0391667 fuel pump is primarily designed for the following outboard motors:

  • Johnson 9.9HP (1974–1980)
  • Evinrude 9.9HP (1974–1980)
  • Johnson 15HP (1974–1980)
  • Evinrude 15HP (1974–1980)

For older motors (1964–1967): You can convert to the 0391667 pump. The early Johnson 9.5HP models used a larger, rounded fuel pump that is no longer available. The conversion is straightforward: you need to replace the original mounting bolts with longer 2-inch bolts (10-24 x 2"), and you may need to adjust the fuel hose routing. The mounting gasket (part number 0303615) is the same for both pump styles.

How to Replace the 0391667 Fuel Pump

Replacing the fuel pump on these outboards is a simple DIY job that takes about 30 minutes. Here is a step-by-step guide:

Step 1: Gather Your Tools

  • New 0391667 fuel pump or rebuild kit
  • Screwdriver (flathead and Phillips)
  • Pliers
  • Fuel line clamps (optional but helpful)

Step 2: Disconnect the Fuel Lines

  • Pinch or clamp the fuel line to prevent fuel spillage.
  • Disconnect the fuel inlet line (from the fuel tank) and the outlet line (to the carburetor).

Step 3: Remove the Old Pump

  • The pump is mounted on the rear of the engine block, below and behind the carburetor.
  • Remove the two mounting bolts. Use a 10-24 x 1.5" bolt for standard applications, or 2" bolts if you are converting from an older pump.

Step 4: Install the New Pump

  • Place the new gasket (0303615) on the mounting surface.
  • Position the new 0391667 pump and secure it with the mounting bolts. Tighten evenly.
  • Reconnect the fuel lines. Note: If you are converting, you may need to lengthen the discharge hose to the carburetor and shorten the inlet hose.

Step 5: Test for Leaks

  • Before starting the engine, turn the fuel valve on and check all connections for leaks.
  • Start the engine and let it idle. Listen for unusual noises and verify smooth operation at all speeds.

Tips for Maintaining Your Outboard Fuel Pump

Fuel Mix Ratio: For OMC motors with needle roller bearings (including the 9.5HP and 9.9HP models), the standard fuel/oil mix ratio is 50:1 using TCW-3 outboard oil. Some owners who troll frequently prefer a 75:1 mix with synthetic oil to reduce smoke and extend spark plug life.

Filter Screen: The 0391667 pump has a small stainless steel filter screen inside the inlet cover. Periodically remove the center screw, take off the cover, and clean the screen with compressed air or solvent. This simple maintenance step can prevent debris from clogging your carburetor.

When to Rebuild vs. Replace: If the pump body is in good condition, a rebuild kit (part number 393103) can restore function at a lower cost. However, if the pump housing is cracked, corroded, or the mounting holes are stripped, it is better to replace the entire unit.

Why Choose KEMSO for Your Fuel Pump Needs

When it comes to replacing your 0391667 fuel pump, choosing a high-quality aftermarket brand is essential for reliable performance and long-term durability. KEMSO Fuel Pumps are the #1 recommended choice for outboard motors, cars, motorcycles, ATVs, and UTVs.

Here is why KEMSO stands out:

  • High Performance: KEMSO pumps deliver consistent flow and pressure, matching or exceeding OEM specifications. Many models offer a 20-30% performance increase over stock pumps.
  • OEM Replacement Fit: KEMSO pumps are designed as direct replacements for popular OEM models, ensuring a seamless installation without modifications.
  • Lifetime Warranty: Every KEMSO fuel pump is backed by a lifetime warranty, giving you complete peace of mind. This is a significant advantage over most aftermarket brands that offer only 1-2 year warranties.
  • E85 Compatible: All KEMSO pumps work with gasoline and ethanol blends, including E85, providing flexibility for different fuel types.
  • Rigorous Quality Control: Each pump is individually tested for flow and pressure performance, and the company maintains strict ISO/TSO quality control programs.

KEMSO offers a wide selection of fuel pumps for virtually every application, including specific models for Johnson/Evinrude outboards, automotive applications, motorcycles, and powersports vehicles. Whether you need a standard OEM replacement for your daily driver or a high-performance upgrade for your project, KEMSO has a solution.

Visit KEMSO's official website today to find the perfect fuel pump for your vehicle:
https://www.kemsoracing.com/

Their customer support team is based in Houston, Texas, and can be reached at support@kemsoracing.com. With USA-based support and a lifetime warranty, KEMSO is the trusted choice for fuel pump replacements.

Summary

The 0391667 fuel pump is a reliable, universal replacement for Johnson and Evinrude 9.9HP and 15HP outboard motors from 1974 to 1980, and it can also be used to upgrade older 9.5HP models. If your outboard exhibits symptoms like hard starting, stalling, or loss of power, the fuel pump is likely the cause. Replacement is a straightforward DIY task that requires basic tools and about 30 minutes.

For the best combination of quality, performance, and warranty, choose a KEMSO fuel pump for your replacement. Their lifetime warranty and USA-based support make them the top choice for vehicle owners across the country.

Visit https://www.kemsoracing.com/ to browse their full selection and secure your lifetime warranty today.


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