Monster Tech. Fuel System by Capo

slob · 03-01-2011, 01:52 PM

DUCATI FUEL SYSTEM

The following is based upon equipment fitted to an 04 S4R 996 Desmoquattro.
Similar equipment is fitted to other steel tank fuel injected models.

Fuel injection systems provide fuel to the engine under control of the Engine Control Unit (ECU) according to a software “map” contained within the ECU, sensors for engine speed and temperature, throttle position, air temperature and barometric pressure variants also provide a mass air flow measurement and exhaust gas analysis via a lambda probe. The ECU compares the inputs to the map and determines the amount of fuel required, the fuel delivered is varied by altering the time the injector is open (Pulse Width).

The subject machine, uses the Webber Marrelli 5.9 ECU and is not equipped with mass air flow measurement or exhaust gas measurement i.e. open loop. The measurement of air flow is calculated by the ECU from throttle position and engine speed.

The ECU is basically non adjustable, a trim facility is provided for slight adjustment of the fuel mixture over the full range of operation.

The fuel pump is controlled by the ECU, when the ignition switch is turned on, the pump runs for a preset amount of time (3 to 5 seconds), and then runs again when the ECU receives a signal from the rotation sensor. It continues to run as long as engine rotation is detected.

Fuel from the pump is delivered via a filter to a fuel distribution header (or rail) in the case of the Ducati the fuel delivery hose forms the header, the pressure in the header (the system pressure) is controlled by the pressure regulator (set at 3bar), fuel supplied by the pump in excess to the requirement of the injectors is returned to the tank.

The fuel injectors take their supply from the header and atomize the fuel into the throttle body under the control of the ECU.

The pump is located in the bottom of the tank secured by a clip. A fine mesh strainer with a large surface area is connected to the pump suction and serves to protect the inner workings.

Tank Interior

The fuel pump bears the Bosh part # 0 580 453 408 it has an operating pressure of 3 bar and a capacity of 160l/h with no delivery head. Shut off head is 5bar

The pump is a positive displacement type, this means that the pump cannot produce pressure unless it is acting upon a restriction. It also has the characteristic of rising power consumption with rising restriction. At a discharge restriction of 3bar the pump is producing 2.5l/m and is consuming 5A (60W). Voltage is critical to the pump output with both pressure and volume raising and falling with voltage. Pump performance data is referenced to 13.4V at the motor terminals.

The pump is both product lubricated and cooled. It is not advisable to run it dry.

Pump manufacturing tolerances are extremely fine. Motor speeds can be as high as 10,000 RPM and the clearances within the pumping elements down to microns. Cleanliness of the fuel system is vital, with an efficient high quality filter as an essential part of the fuel system.

The 8 micron fuel filter is connected to the outlet of the pump by a hose secured with clamps, a round aluminium canister, the filter is retained in a spring clip secured to the tank. The filter is directional and should be installed with the direction arrow pointing away from the pump.

A visual inspection of the filter is not possible but the current draw of the fuel pump, measured in amps, can indicate a blocked or obscured filter. 5 to 6 amps would be a normal reading.

slob · 03-01-2011, 01:53 PM

The current can be recorded by inserting a ameter in series with the circuit, the current recorded will be lower if the systems pressure is less than the quoted specifications and higher if the flow of fuel is restricted in any way, for example: a blocked filter or a damaged fuel line.

When replacing a pump or filter care should be taken to keep the connecting hoses clean.

The systems pressure is the pressure that is seen within the system between the fuel pump and the pressure regulator, the system pressure is determined by the tension of a spring reacting against a diaphragm to which a valve plunger is attached, the relief pressure is set at a nominal 3bar, it is not adjustable. The diaphragm is referenced to atmospheric pressure on the spring side.

When the required pressure is obtained, the fuel pressure overcomes the pressure of the spring, the plunger lifts off its seat and excess fuel is returned to the tank.
This system due to the nature of its operation will automatically compensate for different fuel demands under different conditions. For example if the fuel requirement is low at engine idle, the plunger will lift and return a greater volume of fuel back to the tank than when the demand is higher, when a smaller amount of fuel is returned. The pressure regulation accuracy is dependant primarily on the quality of the spring and can vary between 2.75 bar to 3.25 bar.

The ECU does not have a fuel pressure input and assumes an injector inlet pressure of 3 bar when determining injector pulse widths, a higher pressure will cause more fuel to be injected thus richening the mixture, a lower pressure will weaken the mixture. It is also assumed that each injector delivers exactly equal amount of fuel. The injector contain a fine screen to catch any particles that could cause a blockage.

Throttle body assembly, the fuel pressure regulator is shown in the foreground.

The fuel tank filler assembly is divided into two parts, a base ring and the filler cap. The base ring fits into the tank opening and seals off the tank with an O ring, a second molded rubber ring seals the flange of the base ring to the tank preventing the ingress of water into the base ring cavity. The ring is secured to the tank by eight 4mm grub screws that screw into groove formed in the tank opening locking the ring firmly onto place. The cavity in the base ring will collect spilt fuel and water that can enter around the filler cap hinge plate. Any such fluids are drained through a hole to a hose that runs through the tank and exits to a wye fitting, the vent hose is connected to the other leg of the fitting the third hose exits below the engine.
It is necessary to remove the base ring in order to gain access to the pump and filter.

Base Ring

The hinged filler cap contains the vent valve, latch and lock barrel. The tank is vented to atmosphere via the filler cap which contains a check valve assembly that permits the escape or admittance of air into the tank but prevents the escape of fuel.
When the cap is closed, a hard rubber ring is pushed by four springs into contact with a ridge surrounding the tank inlet aperture effecting the closing seal. Closing the cap also seals the vent valve outlet against a rubber collar in the base ring, sealing the vent tube from the ingress of fluid and completing the vent path to the hose.

Underside of The Fuel Filler Cap

The vent check valves are contained within the filler cap, under the cover plate is a chamber at the base of which are the inlet and outlet ports. The chamber is at the highest point of the fuel tank and has access to the tank void via a small slot and by the generous clearance of the cover plate.

slob · 03-01-2011, 01:53 PM

The check valves are resilient rubber and cover four 1mm drillings, the application a pressure differential in the correct direction is will cause once the elasticity of the valve is overcome, the valve to lift off of its seat relieving pressure or vacuum from the tank.
When closed, the valves prevent fuel from escaping.
While symmetrical in shape, the valves are not identical, the pressure relief being thicker than the vacuum relief. The valve should be assembled with the notch adjacent to the vent channel

Check Valves

The vent channel is formed between the cap body and top cover plate, a molded rubber gasket seals the channel.

A fuel level sensor is located in the base of the tank and is held in place with a union nut and sealed with an O ring. The sensor assembly is also used as sealed conduit for the pump power leads.

The sensor contains a float that rides on a shaft within the sensors tubular body, a coil of wire is molded into the wall of the tube. The passage of the float within the tube, changes the resistance of the coil, this causes the low fuel light to illuminate when the resistance reaches a predetermined setting.

Fuel Level Sensor

Operational Issues.
The fuel pump will quite happily run all day at a discharge head of 3bar, at that point the flow is sufficient to conduct the heat away from the pump. The problem comes with the increase in discharge head caused by a blocked filter. Consider the following pump curve (not the Bosch but very similar) (Bosch data is impossible to find).

It can be observed that as the discharge (head) pressure increases the amps increase and the flow decreases. At 5bar the current has risen by 28% and the cooling flow has been reduced by 20%.the heating effect of the additional current is exacerbated by the reduction in flow of coolant, resulting in a general increase in operating temperature, the life of the pump is reduced when operated under these conditions. Regular replacement of the fuel filter is the obvious way to avoid pump failures. Symptoms of a blocked fuel filter would include poor performance at large throttle openings becoming progressively worse and at lower throttle openings.

As the pump is lubricated by the fuel, running it dry will cause irreparable damage. If you run out of fuel, turn off the ignition and don’t turn it on again until you have replenished the tank.

As stated above, voltage is crucial to the pump operation, as the voltage falls so will the pump output, the symptoms being similar to that described for a blocked filter only the degradation in performance being much quicker.

Fuel pressure is also critical to the fueling of the engine, the closer to the design pressure of the 3bar the regulator can control too, the better will be the performance as the ECU assumes the 3bar figure. Ideally an adjustable regulator could be set to maintain the 3 bar design pressure, reducing the production tolerance of the non adjustable OEM unit. Such adjustable regulators are available on the accessories market. Irrespective, there is a band within which

slob · 03-01-2011, 01:53 PM

the pressure is maintained. It is apparent that this control band is acceptable, however it could be improved.

When replacing internal fuel hoses, make sure you select a hose that is suitable for immersion in petrol, most fuel hoses are not.

When replacing a pump or filter care should be taken to keep the connecting hoses clean. If you have to remove the tank, cap or cover the ends of the hoses immediately after disconnecting them.

The 4mm grub screws that secure the base ring to the tank, are prone to corrosion and can prove difficult to remove, a little anti seize grease should be applied to the screw. It is not necessary to completely remove the screws when removing the base ring from the tank, but they have to be withdrawn clear of the locating groove in the tank.

The filler cap is not sealed from the base ring, water from washing or rain is free to enter the base ring cavity from where it drains. The drain pipe can block, when this happens the cavity fills up and a surprising amount of water will enter the tank next time the cap is opened. If you notice that fluid not draining, clean out the tube.

Another cause of failure to drain is a kink in the hose between the base ring and the steel tube that runs through the tank. This hose and the vent hose can be readily observed through the tank fill aperture

Some models came fitted with quick dry break connectors on the fuel hoses, these make tank removal much easier. Models that are not equipped can be retrofitted. The couplings are manufactured by Colder Products .

When fitting, consider reversing the orientation of one connector, this will make it impossible to incorrectly connect the fuel lines.

Throttle Position Sensor calibration is essential as the ECU uses the feedback to determine mass flow.

When modifying the intake or exhaust systems, it is unlikely that the ECU map would be suitable. As this can not be adjusted, it requires that means of adjustment has to be provided. Several devices exist that fitted into the control circuit can modify the pulse width according to its own inbuilt (and adjustable) map
Replacement ECU’s are also available that give complete and finer control over all parameters.

slob · 03-01-2011, 02:01 PM

Many thanks to Capo (Stewart) for the above.

03-01-2011, 01:52 PM	#1
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,733	Monster Tech. Fuel System by Capo DUCATI FUEL SYSTEM The following is based upon equipment fitted to an 04 S4R 996 Desmoquattro. Similar equipment is fitted to other steel tank fuel injected models. Fuel injection systems provide fuel to the engine under control of the Engine Control Unit (ECU) according to a software “map” contained within the ECU, sensors for engine speed and temperature, throttle position, air temperature and barometric pressure variants also provide a mass air flow measurement and exhaust gas analysis via a lambda probe. The ECU compares the inputs to the map and determines the amount of fuel required, the fuel delivered is varied by altering the time the injector is open (Pulse Width). The subject machine, uses the Webber Marrelli 5.9 ECU and is not equipped with mass air flow measurement or exhaust gas measurement i.e. open loop. The measurement of air flow is calculated by the ECU from throttle position and engine speed. The ECU is basically non adjustable, a trim facility is provided for slight adjustment of the fuel mixture over the full range of operation. The fuel pump is controlled by the ECU, when the ignition switch is turned on, the pump runs for a preset amount of time (3 to 5 seconds), and then runs again when the ECU receives a signal from the rotation sensor. It continues to run as long as engine rotation is detected. Fuel from the pump is delivered via a filter to a fuel distribution header (or rail) in the case of the Ducati the fuel delivery hose forms the header, the pressure in the header (the system pressure) is controlled by the pressure regulator (set at 3bar), fuel supplied by the pump in excess to the requirement of the injectors is returned to the tank. The fuel injectors take their supply from the header and atomize the fuel into the throttle body under the control of the ECU. The pump is located in the bottom of the tank secured by a clip. A fine mesh strainer with a large surface area is connected to the pump suction and serves to protect the inner workings. Tank Interior The fuel pump bears the Bosh part # 0 580 453 408 it has an operating pressure of 3 bar and a capacity of 160l/h with no delivery head. Shut off head is 5bar The pump is a positive displacement type, this means that the pump cannot produce pressure unless it is acting upon a restriction. It also has the characteristic of rising power consumption with rising restriction. At a discharge restriction of 3bar the pump is producing 2.5l/m and is consuming 5A (60W). Voltage is critical to the pump output with both pressure and volume raising and falling with voltage. Pump performance data is referenced to 13.4V at the motor terminals. The pump is both product lubricated and cooled. It is not advisable to run it dry. Pump manufacturing tolerances are extremely fine. Motor speeds can be as high as 10,000 RPM and the clearances within the pumping elements down to microns. Cleanliness of the fuel system is vital, with an efficient high quality filter as an essential part of the fuel system. The 8 micron fuel filter is connected to the outlet of the pump by a hose secured with clamps, a round aluminium canister, the filter is retained in a spring clip secured to the tank. The filter is directional and should be installed with the direction arrow pointing away from the pump. A visual inspection of the filter is not possible but the current draw of the fuel pump, measured in amps, can indicate a blocked or obscured filter. 5 to 6 amps would be a normal reading.

03-01-2011, 01:53 PM	#4
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,733	the pressure is maintained. It is apparent that this control band is acceptable, however it could be improved. When replacing internal fuel hoses, make sure you select a hose that is suitable for immersion in petrol, most fuel hoses are not. When replacing a pump or filter care should be taken to keep the connecting hoses clean. If you have to remove the tank, cap or cover the ends of the hoses immediately after disconnecting them. The 4mm grub screws that secure the base ring to the tank, are prone to corrosion and can prove difficult to remove, a little anti seize grease should be applied to the screw. It is not necessary to completely remove the screws when removing the base ring from the tank, but they have to be withdrawn clear of the locating groove in the tank. The filler cap is not sealed from the base ring, water from washing or rain is free to enter the base ring cavity from where it drains. The drain pipe can block, when this happens the cavity fills up and a surprising amount of water will enter the tank next time the cap is opened. If you notice that fluid not draining, clean out the tube. Another cause of failure to drain is a kink in the hose between the base ring and the steel tube that runs through the tank. This hose and the vent hose can be readily observed through the tank fill aperture Some models came fitted with quick dry break connectors on the fuel hoses, these make tank removal much easier. Models that are not equipped can be retrofitted. The couplings are manufactured by Colder Products . When fitting, consider reversing the orientation of one connector, this will make it impossible to incorrectly connect the fuel lines. Throttle Position Sensor calibration is essential as the ECU uses the feedback to determine mass flow. When modifying the intake or exhaust systems, it is unlikely that the ECU map would be suitable. As this can not be adjusted, it requires that means of adjustment has to be provided. Several devices exist that fitted into the control circuit can modify the pulse width according to its own inbuilt (and adjustable) map Replacement ECU’s are also available that give complete and finer control over all parameters. Last edited by slob; 03-01-2011 at 02:01 PM..

03-01-2011, 02:01 PM	#5
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,733	Many thanks to Capo (Stewart) for the above. Last edited by slob; 03-01-2011 at 02:03 PM..