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Current status 25 Nov 2018 - FIXED
I live on the Oregon coast near Florence where our summer has been 50-90F degree temperatures. For past six months, my JL has been stalling when driving over a low pass to reach an inland city. I found all I needed was to restart the motor and resume with a lower gear. Often, I noted the loaded engine going into a limp mode as if the turbo was turned off by the #$%^& computer. Then two months ago upon cold starts in the morning, the engine was wimpy again as though the turbo was kept off. After five minutes, a restart of the engine gave me back full power. As time passed, the stalling on the road happened more and more frequent especially if the engine had not warmed up yet. I attributed this to the fuel being heated by the filter head to reduce fuel flow resistance. Now, I can not get out my driveway without the engine quitting; forget about going anywhere! Ultimately, it appears the issue is the fuel rail pressure that normally increases with rpm and load would instead decrease to below the 2500psi operational threshold of the injectors causing the engine to become fuel starved. It turned out to be a dirty Fuel Quantity Regulator (also called Fuel Pressure Regulator (FPR), Fuel Control Actuator (FCA), Magnetic Proportional (M-PROP), Fuel Inlet Metering, etc...) that is attached to the injection pump.
July 2016 – installed after market kit removing the wasteful EGR/FCV system, MAF, intercooler, and related plumbing
Aug 2018 – 103,000 miles - replaced engine oil and filter while checking all fluid levels per maintenance schedule
Oct 2018 – frequency of engine stalling (quitting) increasing looking more at why in vain
Nov 2018 – barely made it home, no longer useable, and expanded diagnostics to find problem
Posts indicating similar problems have suggested the following while none the Fuel Quantity Regulator; guess it can now be added to the list of possible problem sources: crank sensor, MAF, positive wire from battery to starter, computer box ground screw, 02 sensors (shorted heater will cause random stalls)
So far:
.....replaced fuel filter
.....filled empty tank with 10 gallons fresh diesel from local gas station
.....got aftermarket reader since odometer display gives erroneous codes (see codes below)
.....installed temporary inline diesel pump between filter and engine and pulled/discarded gallon of fuel
.....routed inline pump output into gallon jug and put gravity fed tube out to feed injection pump to eliminate air bubble issues
..........bubbles possible from leaks or the vacuum pulling dissolved air out of the diesel, some but not much noted
..........since the injection pump's lift pump portion routes excess to the tank return, most air should bypass
.....MAP (Manifold Absolute Pressure) sensor totally clogged; cleaned it out with special electronic cleaner spray.
.....GreenDieselEngineering says "0093 code is when pump is not able to deliver enough fuel to pressurize the fuel rail properly.
...............Main causes: air leakage in fuel, stuck open injector, leakage on high pressure side, and PCV deviation from expected."
.....Plug in reader shows Fuel Rail Pressure goes from 5K to 13K as I rev the engine to 3Krpm in idle (see below)
..........Aha! discover prior to stall the FRP decreases to below the injector 2500psi threshold starving the engine of fuel = quits
..........stalls happen when engine rpm is steady or increasing; also, when engine is being loaded like driving 100 feet
..........engine starts up without hesitation in my garage; even after a stall/quit situation - in past it occassionally took 10 seconds
.....Per GreenDieselEngineering, routed rubber hose fuel return from backend of rail be routed into my gallon jug
..........found normal operation of 10 seconds small steady flow then reduced to steady minor stream of drips
..........indicates the high pressure side of the injector pump is appropriately only pressurizing that needed by the engine (see below)
.....Per GreenDieselEngineering, then disconnected fuel temperature plug at fuel filter, no change in behaviors noted
.....GreenDieselEngineering suggested could be a sticking Fuel Pressure Regulator on the high pressure fuel pump from Bosch. It is the first part in the fuel system exposed to bad fuel or air and can stick if worn. It is also called the fuel metering inlet valve and controls how much fuel is delivered to the pump. It is attached with 3 torx bolts and a pain to get to.
..........YES - I got it out, cleaned it with spray electronic cleaner, and reinstalled to find the issues appear to be gone. I will be test driving the JL to see if there is any lingering stall issues. It is difficult to remove; but, I was able to without taking anything else apart.
Got engine codes off odometer using ignition key procedure. Ignition switch has Aux-Off-On-DashOn-Starter; so, performed Off->On->DashOn-<On->DashOn-<On->DashOn-<On with codes displayed on the odometer readout. Update using info provided by Flash7210 - I have a plug in reader; but the last two numbers were different in some cases to the odometer readout. Flash7210 pointed out the JL software is programmed to give false data where the last two digits are often switched. Now using the competently programmed inexpensive aftermarket plug in reader for codes and live data.
Engine codes after reset show:
0088 - FUEL RAIL PRESSURE TOO HIGH {only get from erroneous odometer not from aftermarket reader}
.....Flash7210 says Related to the p0093 code.
0093 - FUEL RAIL PRESSURE MALFUNCTION POSITIVE PRESSURE DEVIATION {shows up after engine stalls/quits.}
.....Flash7210 says This will definitely put you into limp mode. Could be a bad fuel rail pressure sensor or loose/bad connection.
0403-EGR SOLENOID CIRCUIT OPEN CIRCUIT
.....Flash7210 says This is because of the EGR delete.
1140-VACUUM RESERVOIR SOLENOID OPEN CIRCUIT
.....Flash7210 says This is because of the FCV that you removed with the EGR delete.
1263 - glow plug #2 control circuit low {code shows up after using car before it stalls}
.....Flash7210 says Bad glow plug. Not a show stopper. But you should replace all your glow plugs if you are still using the factory original ceramic plugs.
Fuel Rail Pressure using inexpensive aftermarket reader live data feed:
.....RPM PSI
.....760 5100 idle
.....1000 6000
.....1500 8700 GreenDieselEngineering confirms these are within expected readings
.....2000 11400
.....2500 12000
.....3000 12400
Function of the Injection Pump gleaned from the Forum posts and elsewhere on the web:
.....The IP consists of both a lift pump to suck fuel (up to 20in mercury at high RPM) from the tank/filter/heater(runs 45F on 85F off) and a pressure pump (4,400-23,000psi) to feed the fuel rail for the injectors. The lift output feeds the pressure pump, pump lubrication, and pump cooling with exceess out a 58psi (73psia) relief valve at the end of the fuel rail. The fuel quantity regulator mounted on the injector pump is controled by the ECM to meter just the fuel needed by the engine sending this onto the high-pressure stage. The radial 3-piston (CP3) pressure pump elevates this feeding the Common Rail Diesel manifold. The operational threshold of the fuel injectors fed from the rail is 2,500psi; below that and the engine is starved for fuel. As engine RPM goes up, both the fuel sucked in and the high-pressure out also increases. {In my situation, it sometimes would go the other way from 5,000 down past 2,500psi causing the engine to stall/quit.} The higher pressures are needed since with the increase in engine RPM there is a reduction in the clock time available to inject the fuel; plus, as the load increases so does the fuel flow down the narrow passages of the injectors.
.....Lifted fuel not needed for the Fuel Quantity Regulaor is sent back to the tank providing some injection pump cooling and lubrication on its way. Most injection pumps can pass minor air bubbles out the return line since vacuum fuel lift systems notoriously suck air into the hoses and cause dissolved gasses to come out of solution. Diesel fuel can be dirty which can damage a pump submerged inside the fuel tank. One solution used in large diesels is an air pump pressurizing the fuel tank pushing the fuel through to the injection pump. Many modify their passenger diesel vehicles with an inline pump between the fuel filter and the injection pump going to a "T" connector placed so air bubbles climb up into a hose along with excess pressure to connect with the fuel tank return line via a check valve. This reduces the load on the IP's lift pump and damage from air in the lines. It also makes changing the fuel filter easier when an engine-off manual-on/off switch is installed. (see below) {I am planning to install such a simple fix to this manufacturer's bean counting shortcoming.}
.....To the tank return line are connected hoses from the injection pump, the fuel rail, from each of the injectors; and soon one from the inline lift pump addition. The injection pump's lift stage generates a pressure with a 58psi relief valve connected to the return (see below warnings). Then there is a Fuel Quantity Regulator held by three bolts located on the side of the injection pump hidden by the alternator. This allows just enough fuel needed by the injectors to go from the lift stage output to the pressure stage input. Once pressurized and in the fuel rail, there is a fuel pressure solenoid off the rear end of the rail to pass excess out via a hose nearby. On middle of the rail is a fuel pressure sensor for computer to monitor. Each of the injectors use the pressurized fuel to both inject fuel into the cylinders and to operate the injection process before going out to the return line.
.....Excess fuel fed from the inline lift pump modification not used by the IP lift pump is returned without fanfare in a quantity dependent upon what pump is used. Excess fuel from the injection pump's lift stage is substantial at idle as I noted it passed into the return line a good gallon per minute. There is little excess fuel from the pressurized rail; I noted a stream for the first ten seconds of operation and then it reduced to just a steady drip. Excess fuel from each injector is very small though consistent since it is used to operate the injection process. To test, connect clear tubing to each injector return, run the engine for one minute, and confirm the length of fuel in each line is similar (some say under an inch). When the excess flow is greater, this could mean a failing system.
gmctd Adding an electric inline pump:
.....The under-hood Fuse Center contains a fuse and relay for an electric lift pump. Relayed power wiring is supplied in the vehicle wiring harness for mounting the pump in or near the fuel tank. {Me - better do it between filter and injection pump}
.....Fused power to the relay is supplied when the IGN switch is in the ON position. ECM controls the relay in two modes, prime and run - a safety feature helps prevent fire in event of accident or other emergency. At power-ON, during WTS, ECM closes the relay to prime the low-pressure fuel system to the Inj Pump - if ECM does not sense pulses from the Crank Position Sensor within 15 seconds, the relay is powered down - relay is powered up again when CPS senses crankshaft rotation, indicating START in progress
Power is maintained until crankshaft stops, which is a saftey feature, or when IGN is switched OFF.
.....pressures ~5-9psi and flow rates ~30gph appear to work best in street installations - bigger is not better, here.
Fuel return line cooler
.....Another cause of air bubbles in the fuel is from overheated diesel common in high temperature environments and near empty fuel tank. This can cause additional damage to the injection pump unless an air bubble removal means is provided. I have noted a charge of air coming from the fuel filter when engine was parked to go into a store; perhaps from the filter head heater.
.....gmctd says "Because of the compact fuel system in the Liberty CRD, an air-over cooler should be installed in the fuel-return line. Return fuel can be at engine coolant temperature and higher as it leaves the injectors and mixes with excess fuel being returned from the Injection Pump. The oem return line in the short-wheelbase KJ does not provide enough surface area required for proper fuel cooling to reduce these high temperatures prior to re-entering the fuel tank. Fuel aeration increases as Diesel fuel temperature increases - in-tank fuel temperature increases even more rapidly as fuel level drops, thus making the Jeep Liberty CRD a prime candidate for an auxilliary fuel cooler. Bosch indictates an in-line return-fuel cooler is necessary in some CRD systems.
GordnadoCRD says; "A CP3 from our jeeps uses an "internal pressure" limit of 58psi.
.....This is the pressure that the gearotor pump supplies to all 3 of it's ports once the engine is running. (the first 2 are prioritized internal supply for lubrication, cooling, and protection of the CP3 unit it's self.) Yet the very same (presumably) CP3 on a dodge Cummins is 180psi, and yet again, on a GM Duramax it is 200psi. Mercedes applications have their own and there is another that I forget that has another internal pressure value yet. This is something that is never outlined on all the Ebay deals where most people think CP3=CP3. It doesn't!"
Last edited by KeithOfOhio on Sun Nov 25, 2018 11:43 pm, edited 34 times in total.
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