Yesterday at work i got a ford focus 1.8 diesel (common rail) to do a sales service on. I went out to the car on the sales pitch and used the glow plugs as it was very cold. It started straight away but when i went to drive it into the workshop it died after setting off, at first i thought i had stalled the engine as quite abit of snow was in front of the wheels. I attempted to restart but it just spun over. It had fuel in but was only just above empty. A salesman put approx £7 of diesel in and tried to start again...no luck... now with a flat battery.
Pushed into the workshop and battery put on charge. Checked for any signs of fuel leaks and also plugged my obd scanner in with pulled up no dtcs. Spoke to another tech at ford down the road who informed me that they had no in tank electric pumps. Removed the return off the high pressure pump and forced fuel through using compressed air down the filler neck, reconnected the pipe once fuel was there and eventually it started and ran fine.
Changed the oil and filter this morning and it started straight up and ran fine for approx 3 mins. Went to drive off the ramp and it cut out and wouldnt restart...
I then connected my picoscope! used the preset sensor...fuel pressure...common rail
Read the waveform notes and backprobed the sensor signal wire. On this engine it had a distributor type 'rail' rather than the conventional rail i'm used to with kia and vauxhall.
First question... when i pressed the space bar and started the live reading on the scope, it automatically had channel B on (i had this on the other day with a canbus fault). How do i reset so it doesnt turn its self on?
I dont think i had enough time on the screen which could be throwing me off in totally the wrong direction. But basically once i rebled the sytem and got the engine running again the sensor matched the case notes almost exactly apart from at idle when the engine was switched off, the voltage just dropped straight off and not gradually (10 seconds approx)
Could this be a leaking injector or pump? If it was on the low pressure side ie fuel filter then surely it wouldnt start straight up?. I figured something was causing the problem as i accelerated off the pitch and my ramp...
My next plan was to scope the injectors but the salesman booked it into ford and i had to come away from it. This afternoon i was told that the fuel filter was replaced as it was blocked??? only time will tell if the fault is fixed and the car runs ok.
What do you think to what i've captured with the scope, am i barking up the wrong tree. It was very interesting to say the least...