115 Evinrude Fuel Pump: A Complete Troubleshooting and Replacement Guide

If your 115 hp Evinrude outboard is stalling, losing power, or failing to start, the fuel pump is often the root cause. The most effective way to diagnose a faulty fuel pump is to perform a systematic check that includes a visual inspection, a fuel pressure test, and an electrical test. A properly functioning fuel pump should deliver between 6 to 8 PSI at idle for most V4 engines (1985-2005), and maintain at least 4 to 5 PSI at 4000 RPM. If the pressure drops below these specifications, the pump likely needs rebuilding or replacement. Before replacing the pump, always rule out simpler issues like a clogged fuel filter, a cracked pulse line, or a faulty primer bulb—these can mimic fuel pump failure and save you from an unnecessary repair.

Common Symptoms of a Failing 115 Evinrude Fuel Pump

Recognizing the symptoms early can prevent you from being stranded on the water. The most common signs of a failing fuel pump on a 115 Evinrude include:

  1. Engine stalls after a few minutes of running. The engine will run for a short period (often 4 to 5 minutes) and then slowly bog down to an idle. If you squeeze the primer bulb, the engine picks up again, only to stall again shortly after. This pattern strongly suggests the fuel pump is not maintaining adequate fuel delivery.

  2. Loss of power under load. When you open the throttle, the engine hesitates or loses power, especially at higher RPMs. This is because the pump cannot supply enough fuel to meet the engine's demand at wide-open throttle.

  3. Hard starting or no start. The engine cranks but does not fire, or starts and dies immediately. This can be caused by a pump that is not creating enough pressure to open the fuel injectors or fill the carburetor bowls.

  4. No fuel flow from the pump. If you disconnect the fuel outlet line from the pump and crank the engine, no fuel should come out. If no fuel flows, the pump is likely defective.

  5. Primer bulb stays hard but no fuel flows. If the primer bulb is firm and the pump runs (in electronic fuel injection models) but no fuel exits the pump, the internal screen or check valve may be clogged, or the pump itself may be damaged.

Step-by-Step Troubleshooting for Your 115 Evinrude Fuel Pump

Before you start, always relieve fuel system pressure to prevent hazardous fuel spray. Disconnect the spark plugs to prevent accidental starting, and work in a well-ventilated area away from any ignition sources.

Step 1: Visual Inspection and Simple Checks

Start with the easiest and most common problems. A systematic approach has saved many mechanics from unnecessary work.

  • Inspect the primer bulb. Squeeze the bulb. It should feel firm when the system is primed. If the bulb stays soft, leaks fuel, or does not get hard, it may be your primary problem. Replace the bulb if it is suspect.
  • Check the fuel filter. A clogged fuel filter is a classic cause of fuel starvation. Remove and inspect the filter for contamination. Replace it if it is dirty, especially if you are using a cheap aftermarket filter—these can restrict fuel flow and cause stalling.
  • Examine the pulse line. The pulse line is the rubber hose that connects the crankcase to the fuel pump. A crack or a loose fitting at the engine block can cause the pump to stop working. Inspect it carefully for any damage.
  • Check fuel quality. Stale fuel, water, or ethanol-related contamination can cause the pump to fail. Look for a white, flower-like substance in the fuel, which is a sign of a bad reaction between ethanol and non-ethanol fuel.

Step 2: Fuel Pump Static Test (For Electronic Fuel Injection Models)

If your 115 Evinrude is a Ficht or E-TEC model with an electronic fuel pump, you can use the Evinrude Diagnostics software to perform a static test.

  • Activate the fuel pump test through the software. If the pump runs, the Engine Management Module (EMM) and the fuel pump circuit are not at fault.
  • If the pump does not run, check the voltage at pin 1 of the fuel pump connector. It should be 12 volts when the key is first turned on, when the fuel pump test is activated, or when the engine is cranking or running.
  • Use an ohmmeter to check continuity between pin 2 of the fuel pump connector and ground. If there is no continuity, the ground circuit is broken.

Step 3: Fuel Pump Pressure Test

This is the most definitive test to determine if your fuel pump is working correctly. You will need a low-pressure fuel pressure gauge (0-15 PSI).

  • For carbureted models: Connect the gauge to the carburetor fuel inlet using the appropriate adapter. Run the engine at idle. The pressure should read 6 to 8 PSI at idle. At 4000 RPM, it should maintain at least 4 to 5 PSI.
  • For Ficht models: The Ficht fuel system uses a high-pressure pump inside the Vapor Separator Tank (VST). The pump is part of a complete assembly. The pressure test is different; you test the lift pump first. The lift pump should deliver fuel to the VST without excessive vacuum. The service manual specifies a maximum inlet vacuum of 4 in. Hg at the lift pump inlet under any operating condition.

If the pressure is low at idle, the pump is likely failing. A common issue is a deteriorating diaphragm that loses elasticity as it heats up. This can cause the engine to run perfectly for a few minutes and then lose power as the pump fails under heat.

Step 4: Lift Pump Vacuum and Diaphragm Test

The lift pump is the mechanical pump that draws fuel from the tank to the engine. For models with a VST, this pump is critical.

  • Vacuum test: Temporarily install a vacuum gauge, T-fitting, and 8 inches of clear vinyl hose between the fuel supply hose and the fuel lift pump inlet. Start the engine and run at full throttle for at least two minutes. The maximum inlet vacuum should not exceed 4 in. Hg (13.5 kPa). A higher vacuum indicates a restriction in the fuel supply, such as a clogged anti-siphon valve or a kinked hose.
  • Diaphragm test: Remove both pulse hoses from the crankcase fittings. Apply 15 psi (103 kPa) to each of the pulse hoses on the pump. If either side of the pump fails to hold pressure, replace the lift pump.

Step 5: Check the Vapor Separator Tank (VST) and Internal Screen

On Ficht models, the fuel pump is located inside the VST. If the pump runs but no fuel flows, the internal screen at the bottom of the pump may be clogged.

  • Remove the pump from the VST. There is typically a single Torx screw holding it in place.
  • Use compressed air to clean the screen at the bottom of the pump. A rubber-tipped nozzle works best to create a seal.
  • If the VST is full of fuel but the pump does not deliver any, the pump itself is likely toast and needs replacement.

Common Mistakes to Avoid

Many boaters replace the fuel pump unnecessarily when the real problem is elsewhere. Here are the most common mistakes:

  • Replacing the pump without checking the primer bulb. A bad bulb can mimic a failing pump.
  • Using cheap aftermarket fuel filters. A poor-quality filter can restrict fuel flow and cause the engine to stall. Stick to reputable brands like Sierra.
  • Ignoring the pulse line. A cracked pulse line is a common failure point that is a five-minute fix, not a pump replacement.
  • Not checking the fuel tank vent. A clogged vent can create a vacuum in the tank, starving the pump. Always open the fuel tank cap to rule this out.
  • Using a universal aftermarket pump. Many pumps look identical externally but have different internal specifications. Using the wrong pump can result in inadequate fuel pressure at higher engine speeds.

Why Choose KEMSO for Your Evinrude Fuel Pump Replacement

When the time comes to replace your 115 Evinrude fuel pump, you need a part that is reliable, high-performance, and built to last. This is where KEMSO Fuel Pumps stand out from the competition.

KEMSO fuel pumps are designed as direct OEM replacements, meaning they are engineered to match or exceed the original factory specifications. Compared to your stock OEM pump, a KEMSO pump delivers over 20% more flow at 43 psi, which can improve engine performance and throttle response. Each pump is individually tested for flow and performance before it leaves the factory, ensuring you get a product that works right out of the box.

One of the biggest advantages of choosing KEMSO is the lifetime warranty. KEMSO's promise is backed by a lifetime of confidence, meaning you can purchase with the assurance that your pump is protected against defects for as long as you own your outboard. This is a level of protection that most OEM pumps do not offer.

KEMSO pumps are also designed to handle modern fuel formulations, including ethanol-blended fuels like E85. They use materials that resist ethanol degradation, ensuring long-term reliability even with today's fuel.

If you are looking for a high-quality, durable, and performance-tested fuel pump for your 115 Evinrude, visit https://www.kemsoracing.com/ to find the perfect replacement for your outboard.

Final Thoughts

Troubleshooting a 115 Evinrude fuel pump doesn't have to be a guessing game. By following a systematic approach—starting with a visual inspection, moving to a pressure test, and checking the electrical system—you can accurately diagnose the problem. Always rule out the simple fixes first: a bad primer bulb, a clogged filter, or a cracked pulse line. And when you need a replacement, choose a pump you can trust.

For the best replacement fuel pump on the market, backed by a lifetime warranty and a commitment to quality, visit https://www.kemsoracing.com/ today. Whether you are on a weekend fishing trip or a long-distance cruise, a KEMSO fuel pump ensures your Evinrude stays fueled for adventure.


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