Technical 2019 Ducato 2.3 140 Swift Escape Compact C502 not starting

[NickoftheDales]

Hi
Althought its a MH I think this is Ducato issue. Had MH 3.5years with no issues during 10k miles. Two months ago after a 50+mile journey stopped for about 1.5hrs. Went to start but turned over but did not start after many tries. Called breakdown. Said something about fuel temp sensor might be faulty and check when get home, bled air from fuel pipe into filter and did a code reset. It started so we continued and arranged to pickup part ordered over phone. Went to Fiat main dealers but part wrong and diagram did not show part. Continued with holiday without issue. Concluded that the Fuel temp. sensor should not prevent engine starting.

Last week came back from trip round yorkshire and stopped at home to empty out. Went out and hour later to move engine turned over but did not start after repeated tries. No fault lights showing (or glow plug or padlock) when ignition turned on and Autel Maxilink ML329 showed no codes for two modules seen. Mobile mechanic got a COA38 code but did not go further as no access to code info. Assumed no diesel getting through which I confirmed when removing filter-in pipe and no diesel. Pump relay removed and tested ok. Fuel pump power shows 5v but assume thats meter on minimal load. Resistance across the pump power supply was 2ohms so not sure if that is ok.

So not sure if I need to remove fuel pump or take to garage to see if its a bigger problem. Still not sure what COA38 means as internet search returned nothing.

Thanks for any further advice as running out of options and next step could be expensive.

 

[varesecrazy]

It there definitely reliable power at the 'lift pump' tank pumps terminals ?

Only temp related vehicle issue Ive had was a dodgy relay ( immobilised)

 

[NickoftheDales]

Hi
Just put a 12volt battery across the pump terminals and it ran ok so think you may be right. Will try a new one and potentially save a fortune. Will keep updated.

Cheers.

 

[theoneandonly]

Hi
Just put a 12volt battery across the pump terminals and it ran ok so think you may be right. Will try a new one and potentially save a fortune. Will keep updated.

Cheers.

will try a new one what battery or pump or relay? the fuel temperature sensor is part of the pump.
please advise when sorted.

 

[Communicator]

Hi
Althought its a MH I think this is Ducato issue. Had MH 3.5years with no issues during 10k miles. Two months ago after a 50+mile journey stopped for about 1.5hrs. Went to start but turned over but did not start after many tries. Called breakdown. Said something about fuel temp sensor might be faulty and check when get home, bled air from fuel pipe into filter and did a code reset. It started so we continued and arranged to pickup part ordered over phone. Went to Fiat main dealers but part wrong and diagram did not show part. Continued with holiday without issue. Concluded that the Fuel temp. sensor should not prevent engine starting.

Last week came back from trip round yorkshire and stopped at home to empty out. Went out and hour later to move engine turned over but did not start after repeated tries. No fault lights showing (or glow plug or padlock) when ignition turned on and Autel Maxilink ML329 showed no codes for two modules seen. Mobile mechanic got a COA38 code but did not go further as no access to code info. Assumed no diesel getting through which I confirmed when removing filter-in pipe and no diesel. Pump relay removed and tested ok. Fuel pump power shows 5v but assume thats meter on minimal load. Resistance across the pump power supply was 2ohms so not sure if that is ok.

So not sure if I need to remove fuel pump or take to garage to see if its a bigger problem. Still not sure what COA38 means as internet search returned nothing.

Thanks for any further advice as running out of options and next step could be expensive.

Hi
Just put a 12volt battery across the pump terminals and it ran ok so think you may be right. Will try a new one and potentially save a fortune. Will keep updated.

Cheers.

Hi Nick,

Your seem to have localised your problem to the LP or lift pump 12V power supply. Perhaps you noticed that the pump was not running when switching the ignition on?

I see no mention of checking the inertia switch. This is normally connected in the pump negative connection. I think that in the x250, the inertia switch is located in the footwell. Worth checking. For a guide only I am attaching a photo of the under bonnet inertia switch on my x244, but I have seen exploded diagrams of the workings. There is a reset button on top.

I am not happy with your electrical measurements. 5V is totally inadequate for a 12V pump supply. How was this reading taken? The only definative test would be across the pump connections, when the pump should be running. Not easy to do, but perhaps by back probing the connector.

Was your reading of 2 ohms across the pump when disconnected, if so the pump has been proven by your applied 12V testing. 2 ohms does not seem unreasonable for the resistance of the pump motor.

 

[NickoftheDales]

Hi
Update.

Did check the inertia switch which was not activated.

Decided not to bare the pump 12v supply wire so found a under bonnet Fuse/relay diagram in the 2006 e-training manual from this site download which appear to apply to mine because the shape and position of the fuses and relays relate. My Fiat manual only identifies the fuses. The Red fuel pump relay T10 appears to be next to the fuel pump fuse F21. Not the big T07 I was told by the second mobile mechanic which is in fact the Fan relay which makes sense at 50amps. So I just swapped the T10 with the spare T20 and hey presto the pump ran when I turned on the ignition and the engine started straight away. Only problem now is finding a replacement spare as Mopar don't show one and ebay has ones at £2.89 which sounds like they will last about 5mins if they work at all.

As a side note there appears to be a temperature sessor (Not sure what else it could be) embedded at 90 degrees into the rubber hose with a rubber surround that then connects into the top of the fuel filter bolted to the bulk head behind and above the fuse box. So the advise from the breakdown guy that the sensor was faulty was misleading.

Still not sure what the COA38 fault code was but assume it was a fiat specific one.

 

[varesecrazy]

Hi
Update.

Decided not to bare the pump 12v supply wire so found a under bonnet Fuse/relay diagram in the 2006 e-training manual from this site download which appear to apply to mine because the shape and position of the fuses and relays relate. My Fiat manual only identifies the fuses. The Red fuel pump relay T10 appears to be next to the fuel pump fuse F21. Not the big T07 I was told by the second mobile mechanic which is in fact the Fan relay which makes sense at 50amps. So I just swapped the T10 with the spare T20 and hey presto the pump ran when I turned on the ignition and the engine started straight away. Only problem now is finding a replacement spare as Mopar don't show one and ebay has ones at £2.89 which sounds like they will last about 5mins if they work at all.

Good to hear it was the relay


It shouldnt be make specific..

The layout is normally shown on the plastic body of it..

And an I.D number ;-)

You just need a good shop..

Worth trying Halfords..??

Ask at the parts counter with your own for reference



Do let us know how it goes..

Could look it up for you on Monday

 

[Communicator]

Most important. If purchasing a replacement relay, you need to select one with a resistor supression resistor across the coil. This to protect the ECU from spikes when relay is switched off. Do not use one with diode, as Fiat do not adhere to standard coil polarity.

I am pleased that you have found the fault.
Be assured that in about 75 years of playing, working with, and using relays, I have found that failures are rare. Yours is only the second Ducato relay fault that I have seen on this and several other forums. Other faulty relay was for a heater fan which is quite a high load, also that failure may have been due to the connections rather than the relay itself.

Do not be too critical of relays sold on Ebay. Vendors such as "3 way components" and "Switch Electronics" sell quality components.

 

[varesecrazy]

Most important. If purchasing a replacement relay, you need to select one with a resistor supression resistor across the coil. This to protect the ECU from spikes when relay is switched off. Do not use one with diode, as Fiat do not adhere to standard coil polarity.

I am pleased that you have found the fault.
Be assured that in about 75 years of playing, working with, and using relays, I have found that failures are rare. Yours is only the second Ducato relay fault that I have seen on this and several other forums. Other faulty relay was for a heater fan which is quite a high load, also that failure may have been due to the connections rather than the relay itself.

Do not be too critical of relays sold on Ebay. Vendors such as "3 way components" and "Switch Electronics" sell quality components.

Just checked..

vehicleproducts.co.uk

List their 30 Amp diode type relays at
£5.32 for the 4 blade
£5.98 for the 5 blade

 

[Communicator]

Just checked..

vehicleproducts.co.uk

List their 30 Amp diode type relays at
£5.32 for the 4 blade
£5.98 for the 5 blade

Sorry, perhaps I did not express myself with sufficient clarity. Do not use relays fitted with a diode on any Fiat base vehicle, instead use one fitted with a resistor in parallel with the coil.

Diode equipped relays follow the Bosch terminal connection standard, where the coil terminal 86 is positive. Fiat do not follow this convention, and actual testing on my x244 has confirmed that both terminals 85, and 86 may be used as the positive.

Plugging a diode fitted with a diode into a socket where 85 is positive, will either blow the fuse or the diode, or both. If the diode is destroyed, and a blown fuse is replaced then any electronics controlling the relay will be at risk of damage.

 

[varesecrazy]

Thank you
@Communicator

I was more offering a view of sellers and prices than the finer details

Your instructions were clear

 

[NickoftheDales]

Yesterday started MH ok to go on trip but stopped after 7miles to check rattle. Would not restart so needed breakdown and as could not be fixed recovery to my local garage after about 6hrs. Garage cannot do anything for a week so will report when I can. Did get replacement relays with resistors. Suspect either bad relays unlikely both or fuel pump issue.

 

[NickoftheDales]

Final Update hopefully. Garage electrical diagnostics found a high resistance in the pump circuit and eventually traced it to a connector behind the passenger door vertical foot recess panel. Not sure if it was disturb during swift coachwork or original assembly. Suspect former as pump access panels missing some retainers probably done when fitting captains chairs as pump cable run appeared strained.

 

[varesecrazy]

Thanks for the update

Looks like a proper conclusion..
And still enough good weather to get out and enjoy it