Technical 2013 2.3 Ducato turns over then cuts out almost immediately

[ducato23hymer]

Can anyone help with this?

I have a 2013 2.3 Ducato Chassis Hymer motorhome. I have owned for 5 months and done 12k miles with no issues. It has done 53k miles in total. It was previously owned by 2x individuals and is excellent condition. It went for a full service 3 weeks ago. I have driven a few hundred miles since the service.

During a road trip, a problem presented itself. We had pulled over for a toilet stop. When restarting the engine... The engine started but cut out 2 seconds later. The engine light came on and dash warning "check engine". I persisted, and managed to get engine running again (and stayed running) by just turning the key and trying a few times. I drove to a nearby garage 10 miles away. After parking up and switching off the engine the problem came back.

The AA
The AA came out. Read the fault codes - common rail sensor fault.
He tapped the EGR and the engine ran. BUT, when i tried to rev the engine it then cut out.
We then disconnected and reconnected the common rail sensor. The engine ran, and this time i could rev the engine. We left it running idle for 2 minutes. Switched engine off, then tried to run the engine again. Problem was back again. It just kept cutting out after a couple of seconds tick over.
We changed the common rail sensor - no change. We put back the original.

Fiat dealer
Hymer was transported on back of truck to nearest Fiat dealer. They ran diagnostics and said the crank speed sensor was faulty. They replaced the sensor and cleared the fault codes. No improvement, problem still happens - cuts out after 2 seconds.

The aftermarket immobiliser was checked and eliminated as a source of the issue. This was done by a professional who installed it. We did this because the Fiat dealer said it could be this, so i wanted to eliminate this straightaway.

Does anyone who is an ace mechanic on these engines know what this could be please? Frankly, is seems like a fuel starvation or airflow related issue, but I'm no mechanic.

Thank you.

 

[Anthony489]

Hi ducato23hymer

I'm more armchair mechanic than ace mechanic but I'll have a go !

I think its rather unlikely to be an intake air supply issue, the amount of air needed at idle is quite small and the engine would only cut out if the air supply was completely restricted and it's hard to imagine this happening. A fuel supply problem seems more likely.

The AA read a code related to common rail fuel pressure. This could mean that A) The sensor (or its wiring) is faulty and the pressure is OK, or B) The sensor is OK and the pressure is not OK. Either way, the ECU will stop the engine running if it thinks the pressure is too high or low. Not unreasonable to try a new sensor, but that didn't seem to clear the fault. This sensor gives a variable voltage related to pressure, i.e. a continous reading not just an on/off or good/bad reading. The pressure is controlled up and down by the ECU according to engine fuel demand.

The fact that the engine consistently runs for a couple of seconds suggests that the pressure starts off high enough but for some reason is not maintained (at least at idle), and once a small amount of fuel has been consumed then the pressure drops too low and the ECU cuts off the engine. A faulty crank sensor can also certainly stop the engine, and they often fail only when hot. However I don't feel your consistent behaviour symptoms fit with a bad crank sensor. I'm not aware of any immobiliser that would cut off an engine after a couple of seconds, but I guess it's reasonable to disconnect it just to eliminate that remote possibility.

The fuel system has a submerged low pressure electric pump in the tank, a fuel filter and a mechanical (engine driven) high pressure pump. The LP pump is controlled by the ECU via Relay T10. I think all these elements need to be checked, especially to check if the LP pump is running and the filter and pipework aren't partially blocked. I don't have definitive information, but I believe that the LP pump must run under all engine conditions to supply the HP pump, i.e. it's not just needed to prime the system before startup and for use at low revs.

Possibly worth noting that the diagnostic equipment used by a main dealer, or even available on the open market as MultiECUscan is capable not just of reading and clearing error codes but also plotting and saving graphs of multiple parameters like desired and actual fuel pressure versus time. In the right hands, this ought to reveal just what's going on in the critical few seconds between starting and cutoff.

I attach a primer on CR Diesel sytems which will probably tell you more than you want to know !

 

[ducato23hymer]

Thank you very much Anthony.... useful to know. I appreciate you taking the time to respond.

 

[lancepar]

"2013 2.3 Ducato turns over then cuts out almost immediately"​

Not the same year or engine management but.........
This describes exactly one of faults when my Ducato was playing up recently. I first thought it was fuel related but after cleaning a connector in the injector wiring, it seems to be behaving itself.

 

[Communicator]

========================================================================The fuel system has a submerged low pressure electric pump in the tank, a fuel filter and a mechanical (engine driven) high pressure pump. The LP pump is controlled by the ECU via Relay T10. I think all these elements need to be checked, especially to check if the LP pump is running and the filter and pipework aren't partially blocked. I don't have definitive information, but I believe that the LP pump must run under all engine conditions to supply the HP pump, i.e. it's not just needed to prime the system before startup and for use at low revs.
========================================================================

My experience is with my earlier 2.8 JTD. I can confirm that on my vehicle, the LP pump should be able torun under all engine operating conditions.

The following quote is from the opening post on another forum, and relates to a 2,3 Multijet.
"Engine starts but cuts out after 30;seconds and throws out the warning light."
That seems very similar to the OP's problem. He may wish to note that the fault was eventually traced to a faulty LP pump.

Here is a link to the thread on the Motorhome Fun Forum.

 

[BurntMarmite]

Dunno if its too old, but MultiECUScan on the new vans can graph pressures and flow for fuel and air, desired against actual.
I'd have thought that'd be a useful starting block?
Airflow, for testing, you can just remove the odd airpipe and allow direct intake - but I'm sure you'd know it was airflow related by the behavious
Could be blocked exhaust (maybe) - just check airflow out.
Could be blocked/leaking injectors?
Any smoke out the back?

Does *sound* fuel related

/armchair nonexpert

edit to add from similar/google: Most likely the engine is starved for fuel. There’s enough to idle but no more. All diesel engines have fuel filters; that’s the first thing to check and replace. Some diesels have a small “lift” pump that transfers fuel from the tank to the injection pump. Confirm the lift pump is working. Check all the fuel lines between the engine and tank. Cracked lines between the pump (or lift pump) and tank can leak air into the fuel lines. If replacing the filter and checking the lift pump and fuel hoses doesn’t get it going,