When starting first thing in the morning, I noticed over a 3 month period that the cranking time (before the engine fired) was getting longer and longer. The fuel pump in the tank was operating OK so I changed the fuel filter to improve the fuel supply to the HP pump. Starting improved for a week or so but, finally, it refused to start after sitting on the drive for a couple of days. My battery is in good condition and was spinning the engine over satisfactorily. I decided to put the battery on charge overnight and investigate further the next day.
The next morning my engine did start but only after cranking for about 15-20 seconds. With the engine now running, I connected my Planet2000 laptop to the diagnostic socket and checked the "Parameters 1 & 2" measurements. Everything seemed normal, the engine was running sweetly and there were no DTCs. I then went for a 10 mile run with Planet2000 still connected to the diagnostic socket and was able to observe the parameters with the car under load. The pressure regulator and 3rd piston de-activation solenoid (on the HP Pump) appeared to be function normally. Also, the common rail pressure seemed to be varying normally in response to throttle changes, ranging from about 275 bar at idle to 1200+ bar under heavy load/acceleration. The instantaneous MPG reading on my RT3 screen was normal and the car's performance was fine. Once started and warmed up, restarting the car was no problem. I decided to leave the car on the drive overnight and do some more checks the next day.
Before trying to start the engine, I removed the outlet hose from the top of the fuel filter (the one going to the HP pump inlet) and pushed a short length of hose onto the filter outlet connector. The open end of the hose was put into an empty plastic water bottle. My wife turned on the ignition so that I could observe the fuel flowing into the bottle. The pressure at the outlet of the filter is supposed to be about 2.5 bar and, although I didn't have the means to measure it accurately, placing my thumb on the end of the hose gave me the sense that it was probably OK. Next, I replaced the connection on the fuel filter and connected up my Planet2000 to the diagnostic socket with "Parameters 1" selected. This enabled me to observe the common rail pressure reading when I tried to start the engine. After 10 seconds of cranking it failed to start and the rail pressure was only about 130 bar. At this point I suspected HP pump failure or a leaking injector. However, whilst researching the Bosch EDC15C2 injection system on the internet I came across an exploded diagram of the CP1 pump which shows a small check valve in the HP Pump inlet pipe. I wondered whether it might be sticking and preventing fuel from reaching the HP pump pistons. My next move was to remove the rubber hose from the HP pump inlet connection. Using a very clean allen key which just fitted inside the inlet pipe, I pressed down on the valve and found it to be quite stiff, but 30 seconds or so of manipulation with the allen key and I could feel the valve moving freely. It has a spring return which is supposed to allow the valve to open when the input fuel pressure exceeds 0.8 bar. I replaced the inlet hose on the HP pump using a new jubilee clip, turned the ignition key and 'Hey presto' the engine fired first time. After a week, the car is still starting first time in the morning as it always used to do.
If your engine becomes difficult to start, but once started runs well with no diagnostic fault codes, a sticking HP pump inlet check valve may be the culprit.
The next morning my engine did start but only after cranking for about 15-20 seconds. With the engine now running, I connected my Planet2000 laptop to the diagnostic socket and checked the "Parameters 1 & 2" measurements. Everything seemed normal, the engine was running sweetly and there were no DTCs. I then went for a 10 mile run with Planet2000 still connected to the diagnostic socket and was able to observe the parameters with the car under load. The pressure regulator and 3rd piston de-activation solenoid (on the HP Pump) appeared to be function normally. Also, the common rail pressure seemed to be varying normally in response to throttle changes, ranging from about 275 bar at idle to 1200+ bar under heavy load/acceleration. The instantaneous MPG reading on my RT3 screen was normal and the car's performance was fine. Once started and warmed up, restarting the car was no problem. I decided to leave the car on the drive overnight and do some more checks the next day.
Before trying to start the engine, I removed the outlet hose from the top of the fuel filter (the one going to the HP pump inlet) and pushed a short length of hose onto the filter outlet connector. The open end of the hose was put into an empty plastic water bottle. My wife turned on the ignition so that I could observe the fuel flowing into the bottle. The pressure at the outlet of the filter is supposed to be about 2.5 bar and, although I didn't have the means to measure it accurately, placing my thumb on the end of the hose gave me the sense that it was probably OK. Next, I replaced the connection on the fuel filter and connected up my Planet2000 to the diagnostic socket with "Parameters 1" selected. This enabled me to observe the common rail pressure reading when I tried to start the engine. After 10 seconds of cranking it failed to start and the rail pressure was only about 130 bar. At this point I suspected HP pump failure or a leaking injector. However, whilst researching the Bosch EDC15C2 injection system on the internet I came across an exploded diagram of the CP1 pump which shows a small check valve in the HP Pump inlet pipe. I wondered whether it might be sticking and preventing fuel from reaching the HP pump pistons. My next move was to remove the rubber hose from the HP pump inlet connection. Using a very clean allen key which just fitted inside the inlet pipe, I pressed down on the valve and found it to be quite stiff, but 30 seconds or so of manipulation with the allen key and I could feel the valve moving freely. It has a spring return which is supposed to allow the valve to open when the input fuel pressure exceeds 0.8 bar. I replaced the inlet hose on the HP pump using a new jubilee clip, turned the ignition key and 'Hey presto' the engine fired first time. After a week, the car is still starting first time in the morning as it always used to do.
If your engine becomes difficult to start, but once started runs well with no diagnostic fault codes, a sticking HP pump inlet check valve may be the culprit.
