Replacing Verado Fuel Floats: A Step-By-Step Guide

The fuel float in a Verado engine is prone to getting stuck in the high position, which can cause the engine to shake and misfire. This is a common issue that can be resolved by replacing the fuel float. The fuel float switch is located inside the Fuel Supply Module (FSM) and can be accessed by removing the bolts holding the FSM body to the engine and then dropping the case. The FSM is mounted on the back of the midsection under a heavy aluminium shield, and the chaps must be removed to gain access to it. It is possible to remove the FSM casing without completely removing it from the engine, but it is a tricky process.

Troubleshooting a Verado fuel float

Step 1: Understanding the Issue

Start by understanding the symptoms and any error messages. Common issues include the engine shaking, missing, or cutting out, as well as increased fuel consumption. In some cases, the fuel float may be stuck in the high position, leading to problems with fuel supply.

Step 2: Basic Checks

Check the fuel lines for any kinks, obstructions, or deterioration. Ensure that the fuel tank vent is clear and functioning properly. It is also recommended to check the fuel filters and replace them if necessary.

Step 3: Inspect the Fuel Supply Module (FSM)

The FSM is a critical component of the fuel system. Inspect the FSM for any signs of damage or deterioration, especially the small tube inside, which is known to deteriorate over time. Drain the FSM protector plate to examine the fuel condition. If there is no fuel coming out of the drain plug, it indicates a potential issue with the fuel pump.

Step 4: Diagnose the Fuel Pump

If you suspect the fuel pump is not functioning correctly, refer to the official Fuel Supply Module troubleshooting guide from Mercury. This guide will provide detailed instructions on diagnosing and resolving issues with the fuel pump.

Step 5: Replace the Fuel Float

If the issue is confirmed to be related to the fuel float, replacement may be necessary. It is possible to replace the fuel float without removing the entire FSM from the engine. Remove the bolts holding the FSM body to the engine, then remove the top screws and drop the case. Replace the fuel float, ensuring that the latest version with red wires is installed.

Step 6: Test and Monitor

After making any repairs or replacements, it is important to test and monitor the engine's performance. Pay close attention to fuel pressure, vacuum readings, and engine behaviour at different RPMs. If issues persist, consult a certified Verado technician for further diagnostics and repair.

Remember to refer to official Mercury resources and seek professional assistance if you are uncomfortable performing any of these troubleshooting steps.

Removing the FSM casing

To remove the FSM casing, you will need to access the Fuel Supply Module (FSM) by removing the "chaps" or cowling from the midsection of the engine. This will expose the heavy aluminium shield that covers the FSM.

First, remove the bolts holding the FSM body to the engine. Next, remove the top 10 or so screws and carefully drop the case. You should now have access to the FSM and can proceed with replacing the fuel float, switch, and filter.

It is worth noting that accessing the FSM can be tricky, and you may need to unplug an 8-wire connector inside the lower cowling to check for continuity between the purple and blue wires. This connector can sometimes be challenging to reach.

Testing the float switch

Step 1: Accessing the Float Switch

Start by locating the float switch, which is part of the Fuel Supply Module (FSM). In most cases, you will need to remove the cowling to access the FSM. This may involve removing bolts and screws holding the cowling and FSM in place. Be careful not to misplace any hardware during this process.

Step 2: Disconnecting the Float Switch

Once you have accessed the FSM, you will need to disconnect the float switch. This typically involves unplugging any wiring harnesses or connectors attached to the switch. Make sure to note the orientation and colour of the wires, as incorrect reconnection may cause issues.

Step 3: Testing the Float Switch

To test the float switch, you will need a multimeter or an ohmmeter. Set the device to measure resistance (ohms). Connect the multimeter probes to the terminals on the float switch. A functional float switch should show some resistance, typically in the range of a few ohms to a few hundred ohms. If the multimeter displays "OL" or infinity, the switch is faulty and requires replacement.

Step 4: Replacing the Float Switch (if necessary)

If the float switch is faulty, you will need to replace it. Ensure you source an exact replacement part from a reputable supplier. Follow the manufacturer's instructions for installing the new float switch, ensuring correct wiring polarity and secure connections.

Step 5: Reassembling the Engine

Once you have tested or replaced the float switch, carefully reassemble the engine. Reattach any cowling or components that were removed, ensuring all bolts and screws are tightened securely.

By following these steps, you can effectively test the float switch on your Verado engine and replace it if necessary. Remember to consult a qualified marine mechanic if you are unsure about any aspect of the process.

Replacing the fuel pump

Firstly, you will need to identify the problem with your Verado engine. One common issue is a stuck fuel float, which can cause the engine to shake and miss. If this is the case, you will need to replace the fuel float.

To begin the process of replacing the fuel pump, you will need to gain access to the Fuel Supply Module (FSM). This is located on the back of the midsection of the engine, under a heavy aluminum shield. You will need to remove the "chaps" from the midsection to access it.

Once you have accessed the FSM, you will need to unplug the 8-wire connector on the port side, inside the lower cowl. This connector runs through a grommet down to the FSM. Unplug it and check the continuity between the purple and blue wires on the connector side going to the module. You should see either no continuity or good continuity, like a reading of 0.2 ohms. If you see a reading in the megaohms scale, the switch is most likely faulty and needs replacing.

At this point, you can replace the fuel pump yourself, saving on some labor costs. It is not a particularly difficult job if you are handy with tools. You will need to source a replacement fuel pump that meets or exceeds OEM specifications. Ensure you get the correct part for your specific Verado engine model and year.

After you have the new fuel pump, simply follow the removal process in reverse to install the new pump. Reattach the 8-wire connector, ensuring a secure connection. Then, reattach the FSM body to the engine and replace the top screws and the case. Finally, you can replace the FSM protector plate and you should be good to go!

Signs of a bad float switch

A fuel float switch is a crucial component that helps control the fuel level in the engine. When the switch fails to detect the rising fuel level, it won't shut off the fuel supply, causing the engine to overflow. On the other hand, if the float switch is stuck in the upward position, it won't allow the engine to receive enough fuel. Here are some signs of a bad float switch:

• Engine Doesn't Start: If your engine doesn't start, it could be due to a faulty float switch. The float switch plays a crucial role in initiating the engine’s cycle. If it fails to signal the engine that the fuel level is appropriate, the engine may refuse to start.
• Engine Doesn't Respond : If your engine is running but you notice that it's not responding as it should, it could be due to a faulty float switch. A stuck float switch can cause the engine to run out of fuel, leading to a loss of power.
• Engine Overflow : One of the most obvious signs of a faulty float switch is engine overflow. When the switch fails to detect the rising fuel level, it won't shut off the fuel supply, causing the engine to overflow.
• Strange Noises : If you start to hear unusual noises coming from your engine, it could be due to a faulty float switch. When the switch malfunctions, it may cause the engine’s components to work improperly, resulting in strange and unexpected sounds.
• Visible Damage or Wear : A visual inspection of the float switch can reveal signs of physical damage, such as cracks or broken components. Additionally, check for any buildup of grime, debris, or mineral deposits that may affect its functionality.

Frequently asked questions