Diesel injection

Hey, guys. Just a wee question.
UK car.
2005 Renault Trafic 1.9 dci
Driving along and cut out. Now a non-start.
Only code is fuel rail pressure sensor.
Scanner reads 0 on fuel pressure PID.
Put verus on (first day using it so I'm VERY inexperienced) and, using component tester, I checked the 3 wires to the sensor.
Ign on. Good ground one wire. Constant 5v, another. No signal on 3rd.
Checked injector pulse on both wires and there was no signal on either.
My question is if the pressure sensor doesn't detect fuel pressure will the ecu not send signal to injectors?
Thanks for any replies.

It will use the last known pressure as a reference,but usually on these systems the ecu looks for a .5volt koeo,its a plausibility check for the sensor,it wont trigger the injectors until it sees a pressure rise to approx 1.3v @sensor,equal to roughly 240bar. disconnect metering valve on high pressure pump it will go fully open to allow max fuel into high pressure pump.
diconnect injectors electrically and watch for a pressure rise at the sensor,Providing the primary side supply is correct,

Failure of the high pressure sensor is a very common crank no start on modern diesels, the high pressure side of the system has to work under extreme conditions. The cam and crank sensors are also major crank no start suspects but if you aren't seeing pressure when cranking then you are on the right track

Yes you are quite right Andy about the crank cam signals being relavent,I was just replying to the suspected rail pressure problem ,I have to say I haven’t seen more than two rail sensors go bad in over all the years of common rail it’s usually some other problem usually a low pressure problem or crank /cam

Landroverman1958 wrote: Yes you are quite right Andy about the crank cam signals being relavent,I was just replying to the suspected rail pressure problem ,I have to say I haven’t seen more than two rail sensors go bad in over all the years of common rail it’s usually some other problem usually a low pressure problem or crank /cam

Yes thankfully you can pick through a lot of the common rail no start faults with just a multimeter. Engine bay low pressure pumps are the most common issue I have seen.
I just bought new seals for a spare Bosch Common Rail BMW-Rover HP pump I intend to overhaul in the next few weeks first time for everything I learned my diesels on big old school marine two strokes that you could climb into the cylinders of.

Well I can’t compete with climbing inside the cylinders,frank Massey always says that most of the common rail fuel issues are on the low pressure part of the fuel system,interesting this week I had to replace an piezo injector in a Citroen berlingo 1.6 which was shorted to negative side of the wafer stack and a drivability issue on a Hyundai 2.9 terracan which was black smoking -2 codes for air flow meter p0100 and p102, replaced after checking air flow signal all my tests are carried out using a verus ,now got an edge,

Maybe it is just me but I find troubleshooting high pressure diesels hard work. So many variables with high/low pressure fuel, turbos, DPF's, emission control systems etc.

Hi to everybody

Would it be possible to check if fuel is flowing on the return side on cranking, would this indicate that low pressure fuel is being supplied at least.

To make the edu pulse the injectors it must receive a minimum pressure signal from the rail pressure sensor. A faulty pressure regulator/solenoid might impede pressure built up...

You could introduce a regulated voltage into the pressure sensor signal wire, read the pressure value with the scanner and try to start the engine. It should start if there was only a fault with the pressure sensor; at least yo'ull have inyector pulse which you can observe in the data stream as well.

Try introducing a fuel source through the intake,if it runs you have a fuel delivery issue or just do a cranking back leakage test.

Thanks for the replies, guys.
I looked at rpm PID on scanner and it read around 200rpm.
I know there was no signal from High sensor so my concern was no fuel in the rail so i disconnected return from rail and turned over. Some fuel came out but i expected more (maybe that is a poor test).
A wee squirt of easy into the intake and it ran so fuel is the problem.
A big reason for suspecting the high sensor is that there was water lying inside the connector around the sensor pins (which sits vertically) and maybe it seeped inside the sensor itself.

Landroverman1958 wrote: Well I can’t compete with climbing inside the cylinders,frank Massey always says that most of the common rail fuel issues are on the low pressure part of the fuel system,interesting this week I had to replace an piezo injector in a Citroen berlingo 1.6 which was shorted to negative side of the wafer stack and a drivability issue on a Hyundai 2.9 terracan which was black smoking -2 codes for air flow meter p0100 and p102, replaced after checking air flow signal all my tests are carried out using a verus ,now got an edge,

Interesting ....

This the test on the low pressure sensor on the Bosch system on BMW M47R in a Rover

www.scannerdanner.com/forum/diagnostic-t...instruction-pdf.html

when the air flow sensor was inspected,i found it was physically melted,,,,,,,,,,,,never seen one melt before,the sensor fitted was the origonal hyundai,i was supplied with a non enuine sensor as the oem replacement was over£300.00+,fitted and no smoke but plot thickens as now thre is still two codes p100 and p102,but we have an extra code p1119 imv fault.
I hate non genuine parts especially critical sensors,so re check readings off new sensor at component and also at pcm,wiring daigram info off haynes pro,but no ecu pin outs,marvellous,,,found wires at ecu which is located in ns behind kick panel,not os as per haynes pro,same readings at pcm as at sensor,the sensor is a bosch unit so off to supplers and got a bosch unit with the same part number,checked air fow body,some one has been making there own diffuser mesh-great,fit complete air flow meter and housing,road test no smke no drivability issues,conclusion,,,,,,,