In this session we will discuss the 2010 & 2013 ISX15 Engine Fuel System. Upon completion of this session you will be capable of: 1. Identifying ISX15 CM2250 & 2350 engine fuel system components, 2. Identifying fuel system component functions, 3. Describing fuel system flows 4. Demonstrating knowledge of fuel system diagnostics.
1
2
3
4
5
6
7
8
The ISX15 CM2250 & 2350 incorporates the Cummins XPI Fuel System. The designation “XPI” identifies the Cummins Common Rail Fuel System from other fuel systems used on various Cummins Engines. Pictured above is the 3 plunger pump. On the ISX15 CM2250 & 2350 engines Cummins uses a 2 plunger pump with diamond like coated steel plungers.
9
Low Pressure Side Functions: Primary Fuel Filter- The OEM must supply a remote mounted, cartridge style suction side fuel filter. The suction side fuel filter must be rated at 10 micron filtration and have a water-in-fuel sensor. Fuel Lift Pump - A fuel lift pump is optional with this engine and will run for one minute following key on at 12 to 14 psi (0.83 to 0.97 bar). Fuel Gear Pump -The fuel pump gear pump, mounted on the high pressure pump, contains an internal valve to regulate its output pressure to 150 psi (10.4 bar). Gear Pump Max Inlet Restriction is 10inHg at Rated Flow With Dirty Filter (6inHg with Clean Filter) Gear Pump Pressures (Typical) 1.9 Bar (Cranking @ 80 RPM), 10Bar (“Rated”), 17 Bar (Maximum Peak Pressure) Allowable Gear Pum p Aux Flow (for doser) 13.7cc/sec Fuel Return Plumbing The new fuel system requires that return fuel returns below fuel level. This is a new requirement for Cummins Heavy Duty engines, but is consistent with medium duty product. The fuel return plumbing is routed to the fuel drain manifold and then to the tank.
10
11
12
13
Air is vented from the fuel system through a vent orifice in the fuel pump actuator housing. If the vent orifice becomes plugged by debris, over pressure faults may occur during engine deceleration. Previous XPI fuel pumps used a venturi air bleed. Always verify that the correct part number is used when replacing the fuel pump head. Fuel is used to cool and lubricate the pumping plungers. Fuel passes through this 50 psi check to provide cooling fuel to the barrel and plungers. Failure of this check valve may cause lower than normal fuel pressure during cranking. The cooling circuit fuel exits the fuel pump through the drain orifice. This cooling circuit was added to the high pressure pump in 2013. Always verify that the correct part number is used when replacing the fuel pump head.
14
FC 3741. Injector Metering Rail 1 Pressure - Data Valid But Above Normal Operating Range - Least Severe Level. A self pumping condition has been detected in the fuel system. Possible causes of this fault code include: High fuel drain line restriction or a plugged fuel pump actuator mounting adapter FC1911 - Injector Metering Rail Number 1 Pressure - Data Valid But Above Normal Operating Range - Most Severe Level. The engine control module (ECM) has detected that fuel pressure in the rail fuel is higher than the commanded pressure. Conditions that can cause Fault Code 1911 or 4727: 1.
Purging air through the fuel system can cause a pressure overshoot, therefore causing Fault Code 1911 to log. A few bubbles exiting the line during the air-in-fuel test is expected. A foamy appearance is an indication of a leak that allows air to enter, a severe inlet restriction that causes cavitation, or a system that is not yet primed. If fuel inlet restriction is not excessive (go to Procedure 006-020 in the applicable service manual), the source of air entry can probably be isolated to one of the following: suction fuel lines, OEM fuel lines, suctionside fuel filter assemblies, or stand pipe(s) in the fuel tank(s).
2.
Sustained periods of very low pressure under load followed by pressure recovery overshoot. This can be caused by high restriction due to plugged filters (Fault Code 559 and 2372).
3.
A tampered fuel pressure sensor that reads low, a biased pressure sensor, or a poor electrical connection.
4.
If an intermitte nt electrical circuit problem with the fue l pump actuator circuit exists, it is possible for Fault Code 1911 to become active, then inactive during normal engine operation. ECM Fault Code 2311 is designed to detect electrical circuit issues with the actuator. Therefore, it is only necessary to inspect for bad connectors or harness issues for Fault Code 1911 if no other fault codes exist. An electric fuel control actuator with excessive leakage will result in high rail fuel pressures at idle or light load.
5.
Other conditions include ECM wiring harness issues such as poor grounds, battery voltage spikes, electrical noise, low alternator output, and large disturbances of battery voltage, as when jump-starting the vehicle or the activation of a large grid heater load.
6.
The fuel rail pressure sensor must also be checked. When checking the fuel rail pressure sensor accuracy, make sure the high-pressure fuel rail is not pressurized. The fuel pump, high-pressure fuel lines, and fuel rail contain very high-pressure fuel. Do not loosen any fittings while the engine is operating. Wait at least 10 minutes after shutting down the engine before loosening any fittings in the high-pressure fuel system to allow pressure to decrease to a lower level. There can be a significant amount of time waiting on the rail to depressurize to zero on some engines. In such cases, it can become necessary to manually relieve the pressure from the high-pressure fuel rail.
15
16
17
18
19
High Pressure Side Function: High Pressure Pump -The high pressure pump has three high pressure pumping chambers and provides high pressure fuel to the high pressure common rail. The high pressure pump raises the fuel pump gear pump output pressure to 35,000 psi (2,413 bar) injection pressure. Maximum Commanded Rail Pressure: 2600 Bar (37709 PSI) at 1800RPM and Higher. Maximum Rated Speed (Automotive):2100 RPM Fuel Rail -The high pressure fuel rail is supplied high pressure fuel by the high pressure fuel pump. The rail acts as an accumulator for pressurized fuel. Due to the high pressure, the fuel actually compresses by about 7 percent. This compression assists in maintaining pressure in the rail during injection, providing minimal pressure fluctuations Fuel Pressure Relief Valve - The high pressure fuel rail and other high pressure components are protected from pressure spikes by a high pressure relief valve mounted on the fuel rail. Injector Supply Lines (High Pressure)High - pressure fuel is transferred from the high pressure fuel rail to the fuel injectors by injector supply lines and head mounted fuel connectors. Injectors -The engine uses electronic fuel injectors, controlled by the ECM. The injectors are equipped with a solenoid that controls the start and end of the injection cycle based on commands from the ECM. Fuel Return Plumbing The new fuel system requires that return fuel returns below fuel level. This is a new requirement for Cummins Heavy Duty engines, but is consistent with medium duty product. The fuel return plumbing is routed to the fuel drain manifold and then to the tank.
20
21
22
23
24
25
26
27
28
CLFC – Close Looped Fuel Control is a function of the CM2350 control system.
29
30
31
32
33
34
35
36
37
38
39
40
41
