Fuel System Checks for No or Hard Starting
Check as follows:
To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.
- Check fuel level and correct if necessary.
- Use DDDL to check for stored or active codes and repair if necessary.
- Using DDDL, monitor the rail pressure while cranking the engine.
- During cranking rail pressure should be above 150 bar.
- If rail pressure is not above 150 bar, go to next step.
- If rail pressure is greater than 150 bar, check for other related engine concerns causing a no start condition (i.e. Camshaft Position Sensor failure).
- If the rail pressure reading is not high enough, look for internal leaks. Refer to "5.1 External and Internal Low Pressure Fuel Leaks" , “Diagnosis External and Internal Low Pressure Fuel Leaks.
- Use DDDL to monitor quantity control valve current while cranking engine.
- If the current measures less than 2800 mA, go to next step
- If the current measures greater than 2800 mA, check for a short to power between pin 1 of the quantity control valve and pin 1 of the 120–pin MCM connector.
- Crank engine for 20 seconds and monitor “LPP Outlet” pressure. Refer to “Low Pressure Fuel System Pressures”.
- If the gauge does not reach 30 psi; go to next step.
- If the gauge is above 30 psi, but below 40 psi; go to step 8 .
- If the gauge is above 40 psi, replace filters.
- Crank engine for 20 seconds and monitor “LPP Inlet” suction pressure. Refer to "5.3 Monitoring Low Pressure Fuel System Pressures"
, “Monitoring Low Pressure Fuel System Pressures.”
- If the gauge does not reach -3 in. Hg; go to next step.
- If the gauge is less than or equal to -3 in. Hg; go to step 9 .
- Check for external fuel leakage and repair if necessary. Refer to "5.1 External and Internal Low Pressure Fuel Leaks" , “Diagnosis External and Internal Low Pressure Fuel Leaks.”
- Check flow from the pressure limiting valve (PLV). Refer to "5.8.2 PLV Leakage Flow Test"
, “PLV Leakage Flow Test.”
- If no flow is noted, go to next step.
- If flow is noted; replace the PLV.
- Install fuel system tool J-48707 and J-48708. This allows the engine to be isolated from the chassis.
- Fill the single container with clean fresh fuel and prime the fuel system using the hand primer.
- Crank the engine for 20 seconds.
- Does the engine start and run?
- If yes, check for loose connections, kinked fuel lines, or issues related to the fuel tank. Repair or replace as necessary.
- If no, go to next step.
- Watch the fuel from the J-48708 tank to the inlet of the fuel filter module. Is fuel reaching the fuel filter module?
- If yes, go to step 16 .
- If no, go to the next step.
- Check the following components
- Check for kinked LPP inlet and outlet lines between filter module and pump.
- Remove and inspect the low pressure pump for wear or broken oldham connection.
- Replace fuel filter module and retest system.
- Watch the return fuel going to the tank.
- Are there large amounts return fuel as soon as the engine cranks?
- If yes, check the three filter caps for proper torque and seating. If this is OK, go to step 17b .
- Remove prefilter, coalescer, and final filters. Check for damaged or missing seals at the bottom of the filters.
- Check the prescreen for debris.
- If all steps have been followed and a starting difficulty condition still exists, call the Detroit Diesel Customer Support Center at 313–592–5800 for help and to decide if you need to replace the high pressure pump.
|DD15 Fuel System Technician's Guide - DDC-SVC-MAN-0037|
|Generated on 10-13-2008|