Replacing Fuel Pump On Johnson Venom 200 Outboard: Step-By-Step Guide

If you're experiencing issues with your Johnson Venom 200 outboard, you may need to replace the fuel pump. A faulty fuel pump can cause a range of problems, including sputtering, misfiring, and rapid fuel consumption. Before replacing the fuel pump, it's important to perform some basic tests and checks to identify the root cause of the problem. This may include testing the compression, inspecting the fuel connections and hoses, and checking the pulse hose and valves. If you determine that the fuel pump needs to be replaced, you can find compatible fuel pumps and repair kits online or through authorized dealers. It's important to follow the correct procedures and safety precautions when working on your outboard motor.

How to identify a bad outboard fuel pump

A bad outboard fuel pump can ruin your day out on the water, but there are some simple ways to identify and troubleshoot the issue.

Firstly, when you try to start your engine, you should be able to hear the outboard fuel pump engaging. If you can't hear that familiar motorized sound, it could be a sign that your fuel pump is having issues. However, it's important to check your battery first, as a weak battery could also be the culprit.

Another common symptom of a bad fuel pump is sputtering or misfiring. If your boat is sputtering, losing speed, or even cutting out completely, it could be a sign of a faulty fuel pump or a clogged fuel filter.

Rapid fuel use is usually another indicator of a bad fuel pump. If you notice your fuel tank is emptying faster than usual, it's worth checking your fuel system for potential issues.

If you're experiencing any of these issues, it's a sign that your fuel pump may be failing. However, it's important to note that what you think is a fuel pump issue could be caused by another component failing, such as a fuel pump diaphragm or check valve. Therefore, it's essential to work through a process of elimination when diagnosing outboard fuel problems.

• Turn off the main electrical cutoff switch.
• Remove the snaps on the outboard motor upper case and take off the cowl cover.
• Take off the spark plug wire boot from the plug tip and move the wire out of the way.
• Use a socket wrench to remove the spark plug.
• Screw a compression gauge hose into the spark plug hole.
• With one hand, twist the throttle position wide open, and with the other, pull the rope start or turn the starter over several times.
• Read the compression gauge in PSI (pounds per square inch). If it falls under 30 PSI, it indicates a compression issue that is preventing the fuel pump from working correctly.
• Check the sump screen to ensure there is enough fuel in the tank and inspect the fuel primer bulb for any leaks or cracks.
• Inspect all fuel connections and hoses for leaks or kinks.
• Loosen the fuel filter hose clamps and check the filter for obstructions.
• Check the pulse hose by loosening the clamp and placing a container underneath, as fuel will discharge.
• With the electric start, ask a helper to crank the engine several times with the ignition cutoff activated and the plug wire removed.
• Connect a fuel pressure gauge to the pulse hose and crank the engine. Normal fuel pumps will have a reading between five and seven PSI. A reading below this range indicates a bad diaphragm or pump check valve.

If you identify any of these issues, you can either replace the fuel pump or opt for a rebuild kit.

Troubleshooting an outboard fuel pump

Next, attach a compression gauge hose to the spark plug hole and twist the throttle position wide open. For an electric start motor, you will need assistance to crank the engine while the throttle is wide open. Then, pull the rope start or turn the starter over four to five times. Read the compression gauge in PSI (pounds per square inch). If the compression falls under 30 PSI, there is a compression issue causing low pulse pressure, which will prevent the fuel pump from functioning correctly.

Another test is to check the sump screen. Ensure there is enough fuel in the tank and check the sump pickup screen for clogs. Blow air through the tank vent to ensure it is flowing freely. Also, inspect the fuel primer bulb for any leaks or cracks.

Additionally, inspect all fuel connections and hoses for leaks or kinks. Loosen the fuel filter hose clamps and remove the filter, then blow through both ends to check for obstructions. If there are no issues, reinstall the filter and tighten the clamps with a screwdriver.

Finally, check the pulse hose by loosening the clamp on the hose, which is connected to the intake manifold and fuel pump. Place a container underneath the hose as fuel will be discharged. For an electric start, crank the engine several times with the ignition cutoff activated and the plug wire removed. If there is a lack of fuel discharge, the issue may be a faulty diaphragm or fuel pump check valve.

Normal fuel pumps will have a fuel pressure of between five and seven PSI. Readings below this range indicate a faulty diaphragm or pump check valve, which will need to be replaced or repaired.

Testing a bad outboard fuel pump

Using a Compression Gauge Hose

Screw a compression gauge hose into the spark plug hole. With one hand, twist the throttle position wide open, and with the other hand, pull the rope start so the engine turns over at least four or five times. If you have an electric start motor, ask an assistant to crank the engine while pushing the throttle wide open. Check the compression reading in PSI (pounds per square inch) on the gauge and refer to your owner's manual for the correct PSI for your engine. If the compression falls below 30 PSI, your fuel pump will not function correctly due to low pulse pressure. In this case, you should first repair the compression problem and then reinstall the spark plug. If the compression seems okay, you can perform the same test on the other cylinders.

Checking the Sump Screen

Ensure there is enough fuel in the tank to be picked up by the sump and that the sump pickup screen is not clogged. Also, check that the tank vent is unclogged by blowing through it and ensuring it flows freely. Inspect the fuel primer bulb for any leaks, cracks, or deformities.

Inspecting Connections and Hoses

Inspect the fuel line hoses and connections from the tank to the fuel pump location for any kinks or leaks. There should be none. Loosen the in-line fuel filter hose clamps and pull out the filter. Blow through both ends of the filter to check for obstructions. If the filter is clear, reinstall it and tighten the clamps with a screwdriver.

Checking the Pulse Hose

Loosen the clamp on the pulse hose, which connects the fuel pump to the intake manifold. Place a container under the hose to catch any fuel discharge and pull the starter rope several times. For an electric start, ask an assistant to crank the engine several times with the ignition cutoff activated and the plug wire removed. If there is no fuel discharge, this could indicate a bad fuel pump check valve or diaphragm.

Using a Fuel Pressure Gauge

Connect a fuel pressure gauge to the pulse hose and crank the engine. A normal fuel pump will have a pressure output of approximately five to seven PSI. Readings below this range indicate a defective fuel pump check valve or diaphragm. In this case, you may need to replace the fuel pump or purchase a rebuild kit.

Testing the diaphragm and one-way valves

Testing the Diaphragm:

• Remove the Fuel Pump: Before beginning the test, it is recommended to remove the fuel pump from the engine, as it will make the process easier.
• Gather the Required Materials: For this test, you will need two 10-24 bolts, four washers, and a hose clamp.
• Clamp and Tighten the Pump: Use the bolts and washers to clamp and tighten the pump. The bolts should be placed through the holes typically used to attach the fuel pump to the engine, with washers on either end to maximize pressure.
• Attach the Fuel Lines: Connect one fuel line to the inlet and another to the outlet of the fuel pump, clamping them tightly.
• Prime the Bulb: Prime the fuel bulb and observe the small hole at the back of the pump. This hole provides a view of the diaphragm, which is an internal rubber part that pushes the fuel through the pump.
• Check for Leaks: If fuel is leaking through the hole at the back of the pump, it indicates a faulty diaphragm. A damaged diaphragm can lead to fuel escaping, causing performance issues or even a complete failure of the engine.

Testing the One-Way Valves:

• Remove the Fuel Pump: As with the diaphragm test, removing the fuel pump from the engine first is recommended.
• Attach the Pressure Gauge Hose to the Outlet: Connect the pressure gauge hose to the outlet of the fuel pump. The outlet is the point from which fuel moves to the rest of the system and may be indicated by an arrow pointing outward.
• Seal the Inlet: Use your thumb to firmly seal the inlet of the fuel pump, which is the point that accepts the flow of fuel and is often marked with an arrow pointing inward.
• Pump the Pressure Gauge: Pump the pressure gauge a few times. If the pressure releases, it indicates that the inlet valve is not functioning correctly, allowing pressure to escape in both directions.

By following these steps and observing the behavior of the diaphragm and one-way valves, you can identify any issues with the fuel pump and take appropriate action, such as repairing or replacing the pump.

Preventing outboard motor fuel pump problems

Dealing with mechanical issues can be frustrating, especially when you are ready to hit the water. To avoid headaches, it’s best to prevent a failure from occurring in the first place. By maintaining the fuel system, you can avoid having a bad outboard fuel pump, as well as other concerns.

Use a fuel stabilizer

Consider using a fuel stabilizer in the fuel if you plan on letting it sit for a while. Before storing your boat for the winter, run the stabilizer through the tank for a few minutes. This will help to keep the fuel fresh and prevent gumming or separation issues that can occur when fuel sits for too long.

Replace the fuel filter regularly

As part of your boat maintenance routine, remember to replace the fuel filter once a year. The fuel filter is located under the engine’s main cover. By replacing it regularly, you can prevent clogs and ensure a consistent flow of fuel to the engine.

Choose the right fuel hoses

When selecting fuel hoses, opt for those with an impermeable liner to prevent degradation. Avoid grey-coated hoses (those with UV protection) as they tend to have more complaints. Instead, go for OEM hoses, which will often last longer. It’s also a good idea to keep some spare hose clamps and hoses on board in case of emergencies.

Keep your flame arrestor clean

The flame arrestor stops flames from contacting other fuel sources, preventing fires. However, over time, it can become clogged, affecting the air/fuel mixture. Regularly clean the flame arrestor with a wire brush or carb cleaner to ensure optimal performance.

Use fresh fuel

Ethanol fuels should not be kept in the tank for more than 30 days. If you are having trouble starting the engine, try using fresh fuel and see if that makes a difference.

By following these tips and providing some TLC to your outboard motor throughout the year, you can increase your chances of avoiding costly fuel pump problems and enjoying trouble-free boating.

Frequently asked questions