Technical Newbie - Having Starting issue with Ducato

[Bradshah]

Hi

I'm just wondering if this could be a problem with the 'throttle' pedal itself. Although unlikely, I think it should be eliminated as a cause. See K055 on the attached diagram. The 'drive by wire' throttle pedal has two potentiometers ('pots') to signal its position to the ECU. Each pot has 3 wires, so a total of 6 wires go back to the ECU. The ECU will check that it gets more or less the same reading from both pots, as a safety feature. I don't know what strategy it uses if this is not the case, but it might prevent running. The pots can be independently checked with an ohmmeter after disconnection.

Thank you kindly for your clear explanation on the throttle pedal and assembly.

We will look to strip this down tomorrow and test.

 

[varesecrazy]

We’ve not tested this yet. All we’ve done so far is open each injector and cranked it, and they all shoot out a load of diesel very powerfully (I know it’s not very scientific l)

If its reliably injecting fuel at cranking speeds - then the pressure is obviously high enough

 

[Communicator]

If its reliably injecting fuel at cranking speeds - then the pressure is obviously high enough

This is a 2.0jtd engine with electromagnetic injectors. Opening the supply line does not prove that the ECU is seeing sufficient pressure to allow injection. It only proves that there is pressure in the common rail. Or have I misunderstood?

DO NOT GET IN THE LINE OF FIRE. Diesel can be injected into the body, causing blood poisoning.

 

[varesecrazy]

My concern was there was 'a bleed' on the rail fittings

Meaning it couldnt sustain rail pressure despite an effective HP pump.

My understanding was it needed to meet a certain pressure before the ECU could trigger injection

 

[Bradshah]

Diagnostic kit plugged into the OBD port should tell you what Rail pressure the ECU is seeing..

If it sees 'low' pressure it will not allow the injectors to fire

(Pressure is Massive.. so this is the safest way of investigating it)

So we are able to check fuel rail pressure from the OBD Port? This is another Avenue we will look into. What would you say is good pressure? Thanks

 

[Communicator]

I have previously posted the eLearn description of the 2.0jtd fuel system on another current thread, and it may be found here. The minimum working pressure is quoted as 150 bars, with engine shutdown at 120 bars.

 

[Bradshah]

I have previously posted the eLearn description of the 2.0jtd fuel system on another current thread, and it may be found here. The minimum working pressure is quoted as 150 bars, with engine shutdown at 120 bars.

Thank you for this information. We will test this and report back with outcome.

 

[varesecrazy]

Thank you for this information. We will test this and report back with outcome.

A figure Cranking

And a figure at @1200 rpm would be helpful

Motor revs spin the pump faster..upping the pressure

Why slow cranking motors will run on a whiff of spray ( not your problem..as they will run : idle ok once warm )

 

[Bradshah]

**UPDATE**

So for the delay in getting back to you all.

We finally managed to test the injectors and 3 were leaking back very badly.

These have now been replaced and it’s started on the first turn of the key.

I want to take this opportunity to Thank the Forum Members for all the Help & Advice.