Section 81.3
SPN 1077/FMI 14

The fault condition is typically related to an internal or external leakage of the high pressure fuel system (too high, Leak Down Test). The MCM monitors rail pressure during engine shut down and compares it to a stored learned value. If the bleed down rate has changed, due to leakage, and it is below the learned value, the code will set.‪

Check as follows:‪

1. Check for multiple codes.
   1. If additional fault codes are present with 1077/14, service the additional fault codes first.
   2. If only 1077/14 is present, go to the next step.
2. Turn the ignition OFF
3. Inspect the following fuel system components for external leakage: high pressure pump, lines to fuel rail, fuel rail, pressure limiting valve (PLV), and fuel lines from rail to injector
   1. If leakage was found, repair as necessary. Refer to "81.3.1 Verify Repairs" .
   2. If no leakage was found, go to next step.
4. Perform PLV leakage test. Refer to "16.10 Pressure Limiting Valve Leakage" , “Pressure Limiting Valve Leakage.”
   1. If the PLV test passed; go to next step.
   2. If the PLV test failed; replace pressure limiting valve. Refer to "81.3.1 Verify Repairs" .
5. Perform amplifier/needle return measurements. Refer to "16.6 High Amplifier/Needle Return Flow (Version 4 Fuel System)" , “High Amplifier/Needle Return Flow”.
   1. If the amplifier/needle return flow test passed; no problem found.
   2. If the amplifier/needle return flow test failed; fix as necessary. Refer to "81.3.1 Verify Repairs" .

Section 81.3.1
Verify Repairs

Verify repairs as follows:‪

1. Turn ignition OFF.
2. Reconnect any electrical connections that were disconnected to perform the diagnosis.
3. Clear codes with DDDL 7.0 or latest version.

   ENGINE EXHAUST ‪
   To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

4. Start and bring engine up to operating temperature (over 140°F/60°C).
5. Verify operation is satisfactory and no warning lamps illuminate. If warning lamps illuminate, troubleshoot the codes. If assistance is required, call the Detroit Diesel Customer Support Center at 313–592–5800.