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Old 04-12-2018, 03:18 PM
chris1973 chris1973 is offline
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Default Non Starting Diesel Doblo 1.9 Multijet

Hi Everyone, just looking for a bit of advice as I have a Diesel Fiat Doblo 1.9 Cargo Multijet on a 55 plate, which refuses to start and of which i've now been trying to fix for some months. I tried replacing the most obvious and easiest things first, replacing the fuel filter, Fuel pump relay and then the Battery, but the problem still wasn't solved.

The in-tank pump is running and there is a good flow of diesel being pumped through the filter and into the intake side of the HP pump, but according to the running parameters the rail isn't seeing the requested pressure it needs to open the injectors during cranking. The rail pressure seems to peak at the start of the cranking, then slowly drops away even as the cranking continues and the RPM is constant.

So as a process of elimination I've replaced the following:-

Rail Pressure Sensor
New Fuel Pressure Regulator on the HP pump
Checked and tightened all injector unions and pipes on the common rail
Removed and cleaned EGR Valve
Removed the in-tank fuel pump and cleaned the filter insert.
Cleaned ECU connector pins

I've also done a physical leak off test on each injector and all fill slowly to within one mark of each other, there is no huge gush of fuel to indicate that there is an injector are stuck open.

Non of the above have got it running, but now there is a P2294 "Invalid Signal" error code logged after each crank attempt, which I believe relates to the Fuel Regulator on the HP pump, which has already been replaced.

I also notice that during cranking the Battery Voltage hovers around 10.5v and often dips under 10v, after a couple of starting attempts from being fully charged. The replacement battery was a cheap Calcium battery to replace the one which was on the Van when I bought it, but it has the same Capacity (60AH) and CCA (540A) and is the same size and type (075) and i'm now wondering if its not up to the Job despite the starter motor managing to crank at 230 - 240RPM. I have charged and refitted the old battery and even tried them both together (linked via Jump Leads) but the results are the same.

I've attached three screenshots showing the various parameters logged by the Diagnostic Software during cranking sessions to see if anybody has any suggestions?. Any advice would be appreciated





A few people have mentioned replacing the Cam Angle Sensor and Crank Sensor, but I am seeing an RPM being displayed and there are no error codes for any of these. The '0' RPM in the data are the result of breaks between cranking, rather than a loss of RPM reading from a sensor.
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Old 04-12-2018, 04:55 PM
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Timbo Timbo is offline
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Hi Chris and first welcome to the site, with common rail the main thing of a no start is the fuel pressure.

You look to be saying that most things check ok, and no major codes.

So lets look at what you can do that will tell you something.

Look at the pressure switch, three wires. with the plug on, use a dc volt meter on say 20 volts, pin it into one of the pressure switch wires with the plug still fitted.

Turn the key on, one wire next wire and the next, one should read 5v, that's the supply, next 0.5 volt this is the output, next about 0v that is the ground, this will say the switch and ecu is ok for a key on test.

The power realy will need to be on for this test, so you may need to turn key off and on if the realy switches off over time.

When you find the 0.5v output wire and your key on test is apx: ok, do a crank test, on the output wire, you need to see 1.2 volt min or more and a fast rise, 1.2 volt here is = to 250 bar of fuel pressure, and is a min: to get the engine to start.

You can do this and let me know what you get.

If we can see the right pressure, we can see what to do next, have you thought about the fuel it's self, has it got petrol, or other in it?

Remember over high pressure will also give rise to a no start, and canbe due to a pump in trouble, if it is it will damage the new reg in a matter of seconds and the injectors as well

Your 10v cranking is fine, if the motor is turning at 200 rpm +.

This will give you something to go at, and will tell you where to start testing, remember 99% of the time a common rail no start is fuel pressure trouble of some kind.

What make of HP pump do you have, some break up, and how did the no start come about, from running or starting after it had been stopped?
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Old 04-12-2018, 07:18 PM
chris1973 chris1973 is offline
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Hi Timbo, Thanks for your prompt and helpful reply.

I'm only getting one related fault code which keeps coming back and that is P2294 which in Fiat Speak on their software translates to "Fuel Regulator 2 Invalid Signal". Having just googled the number in its generic form it basically seems to mean loss of a meaningful signal from the fuel pressure regulator.

It was this P2294 code which led me to replace the FPR on the side of the Injection pump but since the same code remains even with a new regulator fitted, i'm wondering if its worth spending an hour replacing the wiring between the FPR connector and the ECU?. I have had some other wiring problems occurring around the neck of the multiway Tyco connectors which plug into the ECU and i'm now wondering whether the FPR wires might have broken or corroded in the loom too?.

I will test the voltages from the Common Rail sensor tomorrow with a DMM, and report back the voltages, the rail has a brand new Bosch sensor fitted as part of the 'parts darts' exercise, so hopefully it will be OK!.

The injection pump is a Bosch CP3 with the FPR mounted on the side. I did check for signs of swarf in the fuel filter and a sample of fuel taken from the tank and haven't found any obvious metal particles, so *if* it does turn out to be the pump then hopefully it won't have broken up internally, fingers crossed!.

The problem first happened as a hard start, the van which normally started first turn of the key suddenly was taking several seconds of cranking before it fired up, after which it would run fine all day until the next morning, no smoke no loss of power and no sign that there was anything wrong until it wouldn't start again!. I replaced the leak off pipes and the problem went away for about a week, until one morning when it wouldn't start at all and that was back in May! and it hasn't started or moved since, and it became a 'project'. I've spent several months trying to get to the bottom of it.

Unless the Fuel has been contaminated in the Forecourt tanks then it has only been run on diesel, it currently has Shell Nitro+ in it at the moment.

Last edited by chris1973; 04-12-2018 at 07:20 PM.
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Old 04-12-2018, 07:52 PM
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Timbo Timbo is offline
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Sure Chris, wires breaking in the loom is common, but I have never had the FPR wires break, but there is always a first time, the wires from the FPR, go back to the ecm, so you could Bleep them out.

We would use a scope and look at a changing square wave at the FPR, not sure if you can do that or not?

If the FPR is not working it will be seen in the pressure at the switch, i have seen a case where the wrong plug was fitted to the FPR, that's why it ask how it went wrong.

The loom is pulled onto reels and pulled with pins in the cable every 3ft or so, it is this small pin hole that damp gets in and the wire will break off

In every case check at the switch, to see what is going on with the pressure, it is real world and not some made up info from the ecu, that could be missleading.

If wires break most times it will say open or short by the code, not sure what code reader you are using, some will do a lot, others just codes, a code that keeps coming back is a good place to start, but not sure what items make that code with out looking at some ecu data.
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Old 04-12-2018, 08:25 PM
chris1973 chris1973 is offline
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Hi Timbo

It will probably be Thursday before I can work on it again but I will check the continuity between the ECM Connector and FPR connector to see if a wire is broken

I will also check the rail pressure switch voltages, at the switch

I work for an Electronics Manufacturer so I could probably get permission to borrow a scope over the Weekend and also check the FPR signals this way.

I will post back and let you know what I find. I am using the paid version of Fiat multiecuscan software for the data and codes.

Thanks again.

Last edited by chris1973; 04-12-2018 at 08:29 PM.
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Old 04-12-2018, 10:34 PM
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You are most Welcome
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