Bmw R1200gs Fuel Tank: Negative Pressure Causes

The BMW R1200GS is a motorcycle that has experienced issues with fuel pump controllers, which regulate the voltage supplied to the fuel pump and, consequently, the speed it runs at and the rate of fuel supply. The fuel pump controller failures in the BMW R1200GS are caused by two issues related to the poor design of the fuel tank pump housing module, which allows water to collect around the fuel pump controller unit. Firstly, water ingress past the gasket or seal which the controller is seated on can result in corrosion of the electrical connections or shorting. Secondly, corrosion of the fuel controller's finned alloy heatsink can lead to overheating and failure.

Corrosion of the fuel pump controller's finned alloy heatsink

The corrosion of the finned alloy heatsink can cause the fuel pump controller to overheat and fail. This can result in no fuel getting to the engine, causing the bike not to start, or a loss of power while riding.

To prevent corrosion of the fuel pump controller's finned alloy heatsink, it is recommended to regularly check and clean the heatsink, removing any corrosion. A waterproof or anti-corrosion coating, such as ACF50, can be applied and reapplied after cleaning. It is also important to mop out any water that has collected in the recess where the controller is situated, especially after washing the bike.

In 2008, BMW redesigned the fuel tank for the R1200GS models to address this issue, and water should drain more easily from the more steeply inclined position. However, this redesign does not apply to the 2008 R1200GSA models.

Ingress of water past the gasket/seal

The ingress of water past the gasket/seal on which the fuel pump controller is seated is one of the two causes of failure of the R1200GS fuel pump controller. This issue is due to the poor design of the fuel tank pump housing module, which is recessed and causes water to collect around the fuel pump controller unit.

Water ingress past the gasket/seal can result in corrosion of the electrical connections/contacts beneath or possible electrical shorting. This can lead to no fuel getting to the engine, causing the bike not to start, or a loss of power while riding.

To prevent and address this issue, the following steps can be taken:

• Check that the revised seal/O-ring (item 12 in the schematic) in blue colour has been installed for 2004, 2005, and 2006 R1200GS models.
• Inspect the condition of the seal/O-ring and apply a waterproof grease such as silicone.
• Regularly check and clean the fuel pump controller heat sink, removing any corrosion.
• Apply a waterproof/anti-corrosion coating, such as ACF50, and reapply it periodically, especially after cleaning.
• After washing the bike, mop out any water that has collected in the recess where the controller is situated, especially if the bike won't be used for some time.

Faulty controllers being fitted to 2007/2008 bikes

The BMW R1200GS motorcycles from the 2007/2008 model years experienced issues with faulty fuel pump controllers. These controllers, also known as fuel pump regulators, are responsible for managing the voltage supplied to the fuel pump, thereby controlling its speed and the rate of fuel supply to the engine.

The faulty controllers resulted in either a complete lack of fuel reaching the engine, causing the bike to not start, or a loss of power while riding. This issue was caused by two primary factors:

• Ingress of water past the gasket or seal, leading to corrosion of electrical connections and potential electrical shorting.
• Corrosion of the fuel controller's finned alloy heatsink, causing it to overheat and fail.

BMW acknowledged the issue and released a revised fuel pump controller to address the problem. However, some riders continue to report failures even with the new fuel pump controller.

To prevent issues with the fuel pump controller, the following maintenance steps are recommended:

• Check that the revised blue O-ring has been installed for 2004-2006 R1200GS models.
• Inspect the condition of the O-ring and apply a waterproof grease to it.
• Regularly clean and maintain the fuel pump controller heat sink, removing any corrosion.
• Apply a waterproof and anti-corrosion coating to the heat sink.
• After washing the bike, ensure any water collected in the recess where the controller is located is removed, especially if the bike won't be used for an extended period.
• Consider sealing the vents or slots in the black plastic cover to prevent water ingress (although this is not recommended by BMW).

Additionally, there are workarounds available in case of fuel pump controller failure, such as bypass leads or DIY solutions, that can get you back on the road until a permanent fix is implemented.

Faulty fuel pump

A faulty fuel pump can cause significant issues with your BMW R1200GS, and it is a problem that has plagued many owners of these motorcycles. The fuel pump controller (FPC), also known as the fuel pump regulator, is responsible for regulating the voltage supplied to the fuel pump, which in turn controls the speed and rate of fuel supply to the engine. When the FPC fails, it can result in no fuel getting to the engine, causing the bike not to start or, in the worst-case scenario, a loss of power while riding.

There are two main causes of fuel pump controller failure in the BMW R1200GS:

Water Ingress:

The design of the fuel tank pump housing module is such that it can cause water to collect around the fuel pump controller. Water can enter past the gasket or seal and cause corrosion of the electrical connections and contacts beneath, or possibly lead to electrical shorting. This can result in the fuel pump not functioning properly and, consequently, the engine not receiving the necessary fuel supply.

Corrosion of the Fuel Controller's Finned Alloy Heatsink:

The other common cause of fuel pump controller failure is corrosion and overheating of the finned alloy heatsink. The corrosion can lead to the fuel pump controller failing and, in some cases, overheating. This issue is again attributed to the poor design of the fuel tank pump housing, which allows water to collect and come into contact with the heatsink.

To prevent these issues, it is recommended to regularly check and maintain the fuel pump controller and its components. This includes checking the condition of the seal and applying a waterproof grease or coating, as well as keeping the heatsink clean and free of corrosion. BMW has also redesigned the fuel tank for 2008 models to address the issue of water collection, although this change does not apply to the 2008 R1200GSA models.

In the event of a fuel pump controller failure, there are a few workarounds that can get you back on the road temporarily, such as using a bypass lead or performing a controller bypass. However, these are not permanent solutions, and a faulty fuel pump controller will eventually need to be replaced.

Clogged fuel pressure regulator

A clogged fuel pressure regulator on your BMW R1200GS can cause a range of issues, from difficulty starting the engine to complete loss of power while riding. This critical component regulates the voltage supplied to the fuel pump, controlling the speed and rate of fuel supply to the engine.

The fuel pump controller, also known as the fuel pump regulator, is located on the top left side of the fuel tank, under a vented black plastic cover. It plays a vital role in maintaining the necessary fuel pressure for optimal engine performance.

Over time, the fuel pump controller can become clogged or corroded, leading to reduced efficiency or failure. This is often due to the poor design of the fuel tank pump housing module, which allows water to collect around the fuel pump controller unit. As a result, corrosion may occur on the electrical connections and contacts beneath the controller, or the controller's alloy heatsink may corrode and overheat.

To prevent these issues, it is essential to regularly inspect and maintain the fuel pump controller. This includes checking the condition of the seal and applying a waterproof or anti-corrosion coating to the unit. Keeping the heatsink clean and free of corrosion is also crucial.

In the event of a clogged or failed fuel pump controller, there are workarounds available to get you back on the road. These include creating a bypass power lead or performing a temporary controller bypass by splicing specific wires. However, it is important to note that these are temporary solutions, and a permanent fix requires replacing the fuel pump controller with a new one.

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