Technical Puzzling stalling problem

[moodrater]

I just want him to bypass the OEM immobiliser but he won't do it because of the cost to him. It looks now as though I might be moving towards litigation.

The cost to him my bum, if you're very careful and use a dremel to cut off the cover it might take and hour the average mechanic will use a chisel and the job is done in 15 mins.

[edit] later model will need a grinder rather than a chisel

 

[moodrater]

Cobra immobiliser could be cuttin g power to the solenoid too but it sould just as well be a seal in the pump thats letting air in.

 

[fenman]

It's possible but it depends on how the Fiat immobiliser works. The Cobra immobiliser section seems to be hooked into the Key Code Unit, probably in series with the sensing coil, because if I don't disarm it before turning on the ignition the 'Code' warning light comes on. However it doesn't come on when the engine cuts out. It happened again last weekend and I managed to restart it, by declutching and using the starter, whilst still rolling.

I would have thought, from a safety standpoint, that the Fiat immobiliser would only check the code at start-up and not whilst the engine is running (to avoid the exact situation I'm currently suffering from) so that would mean the Cobra couldn't cause the problem.

The problem seems too random to be a faulty pump seal. I'll be taking it on holiday next month when it will probably cover over 1000 miles and I've also started using Millers in the fuel so it will be interesting to see if it gets any better, or worse, with regular use. Once I get back I've arranged for the dealer to have it for an extended period so he can see the fault for himself. Watch this space!

 

[beauxreflets]

It's possible but it depends on how the Fiat immobiliser works. The Cobra immobiliser section seems to be hooked into the Key Code Unit, probably in series with the sensing coil, because if I don't disarm it before turning on the ignition the 'Code' warning light comes on. However it doesn't come on when the engine cuts out. It happened again last weekend and I managed to restart it, by declutching and using the starter, whilst still rolling.

I would have thought, from a safety standpoint, that the Fiat immobiliser would only check the code at start-up and not whilst the engine is running (to avoid the exact situation I'm currently suffering from) so that would mean the Cobra couldn't cause the problem.

The problem seems too random to be a faulty pump seal. I'll be taking it on holiday next month when it will probably cover over 1000 miles and I've also started using Millers in the fuel so it will be interesting to see if it gets any better, or worse, with regular use. Once I get back I've arranged for the dealer to have it for an extended period so he can see the fault for himself. Watch this space!

It may be worth checking that air is not entering through any fuel pipe connections.

While not the same vehicle - I found that a tiny bit of air was creeping in on a loose snap on connector to the diesel filter on a Doblo 1.9 - The engine vibration was breaking the seal sufficiently and periodically so that air blips in the supply would finally gather to create a bubble in the fuel line, to cause "a slight rise in rev's followed by a stall".

The quick fix I used - Was to unclip the connector, slide a small rubber 'O ring' down over the spigot pipe until it sits on the flange; Gently and firmly press the connector back oover the flange, so that when reconnected the O ring seals and takes up the slack.

 

[fenman]

The nature of the fault doesn't chime with it being an air leak. The fact that it can be re-started more or less immediately using the starter but can't be bump-started points to an electrical issue.

 

[moodrater]

The nature of the fault doesn't chime with it being an air leak. The fact that it can be re-started more or less immediately using the starter but can't be bump-started points to an electrical issue.

Actually the top shaft seal gives very similar symptoms in the cutting out department but usually only on older pumps pre 1996 that had plain rubber seals, the later ones are viton and not as prone to failure. Doesn't explain not being able to bump start it.

From an electrical point of view I always start with the aftermarket stuff. I'd be doing is diconnecting that cobra immobiliser to rule that out. Then its hammer time.

 

[fenman]

I see what you're saying but, for the reasons outlined in my post #23 , I think if it is an immobiliser issue it's much more likely to be in the Fiat one.

If I can get the Fiat unit bypassed and it cures the problem I'd then seriously think about having the existing Cobra immobiliser/alarm replaced with a new one (as it's now over ten years old) and set up to provide an alternative immobiliser with alarm.

 

[moodrater]

I see what you're saying but, for the reasons outlined in my post #23 , I think if it is an immobiliser issue it's much more likely to be in the Fiat one.

If I can get the Fiat unit bypassed and it cures the problem I'd then seriously think about having the existing Cobra immobiliser/alarm replaced with a new one (as it's now over ten years old) and set up to provide an alternative immobiliser with alarm.

Call around you local independents / auto electricians tell them you want the immobiliser bypassed on an old bosch ve mechanical pump. Its literally a 15min job to someone thats done one before.

 

[fenman]

Apparently it isn't. I've just taken it to a local diesel specialist and he says that on my pump the immobiliser/fuel solenoid is protected behind a steel bracket fitted with shear bolts. It would need an angle grinder to get to it and the pump would need to be removed due to restricted access. It would take him about 2 hours after the pump was removed. He thinks it might even need a new solenoid because the connections on the old one might be inaccessible.

He agreed that the immobiliser is the only logical explanation for the problem I've been having.

Tomorrow I've arranged to take it to the local independant that did the MOT and service on it last year to see what they say.

 

[moodrater]

Apparently it isn't. I've just taken it to a local diesel specialist and he says that on my pump the immobiliser/fuel solenoid is protected behind a steel bracket fitted with shear bolts. It would need an angle grinder to get to it and the pump would need to be removed due to restricted access. It would take him about 2 hours after the pump was removed. He thinks it might even need a new solenoid because the connections on the old one might be inaccessible.

He agreed that the immobiliser is the only logical explanation for the problem I've been having.

Tomorrow I've arranged to take it to the local independant that did the MOT and service on it last year to see what they say.

I have personally seen a mechanic take off the steel cover with a cold steel chisel and a couple of well placed blows, granted the vehicle was only worth about 500 quid so the owner was willing to risk damage to the pump rather than pay for recovery. I still reckon you can cut the cover off with a dremel without removing the pump grinder is far too unwieldy. You could probably do the top half with an air cutoff tool.

 

[fenman]

Yes, well we're talking a considerably larger value for this van!

I took it to the local independant today. They seem a good bunch and I trust what they say. The guy said he would try using an air tool to grind off the heads of the bolts in situ but the chances are the pump would have to come off. He looked up the time for this which was about 3.5 hours. He also confirmed what the other guy said about possibly needing to fit a new solenoid. All in, worst case, we're looking at around 300 quid.

 

[moodrater]

That's fair enough for the time dremel isn't something most garages would have the only reason I have one is I got it for 15 quid in a bargain bin in b&q and a boat load of cut off wheels for at 15c each very nifty for tight spaces

 

[hymerhobo]

I took it to the local independant today ... we're looking at around 300 quid.

May I ask what happened? Did you have the solenoid replaced? Did that solve the problem?

I've had an intermittent power problem for some time now, and one of the many theories advanced by many mechanics is a dodgy solenoid connection.

 

[fenman]

Nothing's been done yet. The van is going back in to the dealer this week.

 

[fenman]

Re: Puzzling stalling problem - resolution at last?

Just an update. I took the van in and received a call to say it was ready about a week later. I collected it today and confirmed that they've removed the Fiat immobiliser and fitted a brand new fuel cut-off valve. They've also rejigged the Cobra alarm/immobiliser to disable the glow plugs. They've covered about 260 miles without it cutting out. That's not conclusive because on one occasion it went over 500 miles between incidents but I'm pretty confident that it will have sorted the problem.

The only issue now is that, whatever they did with the Cobra, I can't now arm the alarm because it bleeps continuously!

 

[fenman]

Re: Cutting-out problem

Another quick update. The van has now done nearly 800 miles and had no further problems with cutting out so that has pretty well proved the Fiat/Bosch immobiliser was the cause. I sorted the alarm problem which turned out to be a broken door switch.

I found the engine could be cold-started without the glow plugs in the recent hot weather so I've now had the immobiliser correctly configured by a Cobra installer to cut both fuel and starter. In the process he discovered that when the dealer bypassed the Fiat/Bosch immobiliser he ran a feed directly from the ignition circuit and therefore also bypassed the inertia switch, which I'm not very happy about.