blown99 Posted August 4, 2019 Share Posted August 4, 2019 I had a 2011 F550 flatbed wrecker towed in from a customer that bought this not running. Someone put a new high pressure fuel pump on it. Looks like the return hoses are changed as well. Could only get about 1200psi of rail pressure. Began diag, found fuel gushing out of the pressure relief on the left fuel rail. Replaced the relief actuator, retest, still leaking, replaced the rail and high pressure lines to the injectors for that rail. Truck started. took it for a road test, the fuel return hose at #6 blew off the barb fitting. Reattached, had a fuel leak at #6 return tube connection, replaced the injector, plastic return tube. Ran the engine in the shop, commanded rail pressure at idle to 16,000psi, the engine stalls. I can free rev the engine and power brake the engine and hit 20,000psi no issue, no stalling. Take it for a road test, #6 return hose blows off again, reattach and run a zip tie over the hose, still blows off. Questions are- Should I be looking for something causing a restriction on the return side? Should I be able to command rail pressure to 25K at idle?? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted August 4, 2019 Share Posted August 4, 2019 The common findings on this are DEF contamination and restrictions in the return or an injector with an internal high pressure leak. Quote Link to comment Share on other sites More sharing options...
blown99 Posted August 4, 2019 Author Share Posted August 4, 2019 If I remove all the return hoses and clamp off the rubber lines, run the engine, I will see which one is leaking excessively correct? Quote Link to comment Share on other sites More sharing options...
lmorris Posted August 6, 2019 Share Posted August 6, 2019 My guess is it was run with DEF in the tank and not properly flushed before replacing anything. Remove the lines from the upper filter and let them sit for a few hours and see if DEF crystals are evident in the line. If it's a leaking injector, you only need to run the low pressure pump to see which one is leaking. Here is the procedure: M15 : CHECK FOR FUEL INJECTOR RETURN LEAKS Ignition OFF. Wait 2 minutes. Disconnect the low pressure fuel supply line from the fuel injector return line fitting. Disconnect the fuel injector return line fitting from the secondary fuel filter. Using a suitable clear container, catch any fuel that pours from the fuel return line. Connect the low pressure fuel supply line to the secondary fuel filter. Ignition ON, engine OFF. Access the PCM and control the FPL_CMD (MODE) PID. Command the fuel pump ON. Does fuel come out of the fuel return line? M16 : CHECK THE LEFT BANK FUEL INJECTOR RETURN LINE FOR A LEAKING FUEL INJECTOR Find where the fuel injector return line from the left bank and right bank meet together and using hose locking pliers, pinch the line from the right bank. Access the PCM and control the FPL_CMD (MODE) PID. Command the fuel pump ON. Does fuel come out of the fuel return line? Yes DISCONNECT the fuel injector return lines from the left bank of fuel injectors. CONNECT four suitable fuel hoses to the fuel injector return ports on all of the fuel injectors on the left bank. Using a suitable clear container, catch any fuel that pours from the fuel injector return hoses. Run the low pressure fuel pump while observing which fuel injector is leaking from the fuel injector return hose. INSTALL a new Fuel Injector for the cylinder in which the leaking fuel injector was observed. REFER to the Workshop Manual Section 303-04, Fuel Charging and Controls. CARRY OUT the Reset And Clear The Specified Function Reset Minimum Fuel Mass Adaptions For Cylinder X on the scan tool for the affected cylinder. REFER to Section 2, Clear The Continuous Diagnostic Trouble Codes (DTCs) And Reset The Emission Monitors Information in The Powertrain Control Module (PCM). No DISCONNECT the fuel injector return lines from the right bank of fuel injectors. CONNECT four suitable fuel hoses to the fuel injector return ports on all of the fuel injectors on the right bank. Using a suitable clear container, catch any fuel that pours from the fuel injector return hoses. Run the low pressure fuel pump while observing which fuel injector is leaking from the fuel injector return hose. INSTALL a new Fuel Injector for the cylinder in which the leaking fuel injector was observed. REFER to the Workshop Manual Section 303-04, Fuel Charging and Controls. CARRY OUT the Reset And Clear The Specified Function Reset Minimum Fuel Mass Adaptions For Cylinder X on the scan tool for the affected cylinder. REFER to Section 2, Clear The Continuous Diagnostic Trouble Codes (DTCs) And Reset The Emission Monitors Information in The Powertrain Control Module (PCM Courtesy of Ford. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted August 7, 2019 Share Posted August 7, 2019 Ohhhh that is such a fun test to run sometimes. Quote Link to comment Share on other sites More sharing options...
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