intermittent non starting - again!

[straggler]

I have a 1996 406 XUDT. Beginning in October last year there has been an intermittent starting problem. The engine will turn over but will not fire. The first suspect was the cut out switch (the one on the bulkhead that pops if you have an accident). I replaced that and it seemed to cure the problem.

But a couple of months ago it did it again. I checked fuses, connections to the ECU etc but the engine would eventually fire into life as if nothing was wrong and then run faultlessly. I suspected the anti theft as it seemed to be more likely to do it if I had moved the car with the ignition off or once when I popped the cigarette lighter fuse before trying to start the car. But it would still occasionally do it even if I just got in and did nothing apart from turning the key in the ignition.

It has started doing it regularly now and through a process of elimination, frustration and desperation I discovered that if I left the ignition on and deliberately tripped the cut out switch (by whacking the housing with some pliers) and then reset it a few times I would hear a click from somewhere on the front offside of the engine bay. The car then fires up and I can switch off and back on again with no problems (and once it's running it never cuts out). There seems to be no pattern to it apart from the length of time the car has been standing, and even that is not a regular pattern eg if the car refuses to start I fiddle around, get it going and it will then fire up with no problems after switching it on and off half a dozen times. But the next morning it could be dead.

Any idea as to what it might be? I'm in Germany at the moment and am heading back to the UK next weekend so could do with some pointers! Although I am planning to just keep it running as much as I can once I've got it going but would prefer to avoid getting on and off the ferry embarrassments!

[jasper5]

Check the fuel cut off solenoid on the fuel pump. The pin inside could be sticking.

[straggler]

Is it possible to get at the solenoid without removing the pump?

[jasper5]

On one type the solenoid is right on top of the pump, you just unscrew it....the other type I forget how it fits.

On the one that screws out...the test for the solenoid is to remove the pin and then try to start it, if it starts fine then make sure the pin is nice and clean, switch the ignition on then touch the solenoid to earth...the pin should click back and forth as you touch and release earth.

Be warned that if you remove the pin to test the solenoid the only way to stop the engine is to stall by putting the car in high gear, let the clutch out with the brake on.

This is the difficult type....https://www.youtube.com/watch?v=LZN6X0RIQhY

[straggler]

Cheers for the info. I'll go and have a shuftie and see what I can see (the car is parked away from where I'm staying). I suspect it will be the type that's difficult to get at as the car has an immobiliser.

I can always get the car running (so far, anyway!) and it will do Berlin to Dunkirk on a tankfull so will just cross my fingers next Sunday. And if I do need to turn it off I'll stall it and leave the ignition on. Any idea if leaving the ignition on for a long time with a non-running engine is an issue? Might have to do it at the ferry port.

[straggler]

Just had a look and the surprising news is mine has the solenoid on top of the pump. Looks reasonably straightforward to get to but as long as the car is sort of going I'll wait until I get back to the UK to start messing with it.

And, sod's law applied - the car started with no problems so I couldn't mess around with the cut out switch to see if the solenoid was the problem. But I did cycle the switch multiple times and got the click each time. And I (accidentally) got it to "bounce" when the switch was half-in/half-out. Made a noise like a woodpecker on speed so maybe that will have cleared any gunk that was making it stick.

Will drown the top connection in WD40 later. Watch this space....

[jasper5]

Yes, take off the top connector and make sure it's clean.

Good luck with it

[PeterN]

You could try driving it without the needle valve in the pump but you would have to stall it to stop, but it might prove something.

Peter

[straggler]

Yeah, I will do that if it reoccurs before I get back to the UK. But I'm a great believer in sod's law - in this case a "simple" matter of removing the solenoid to test it/remove the pin - so will leave it alone for now, if I can. Once I'm back home I can break things without it being a disaster!

[straggler]

Ok, so I got back to the UK no problem. The car even started ok to get me off the ferry, which saved a lot of potential embarrassment!

So it conveniently failed to start a little bit later. I did the trick with whacking the fuel cut out and then resetting it and the car fired up straight away. The problem now is - what exactly is wrong?! The solenoid always kicks in when I use the fuel cut out switch, and the cut out switch is not tripping so I am not sure where the fault is. The car never fails to switch off on the key so I am not sure why the solenoid would only stick in one position (and then come back to life immediately when switched on and off with the cut. Might it be a fault somewhere in the circuit from the key to the solenoid eg the ignition is turning on but power is not reaching the solenoid until I reset it?

Cheers!

[straggler]

And back to square one - car has refused to start a couple of times and the cut off switch thing seems to no longer work. Spent about 30 minutes yesterday fiddling around before the car fired into life. The only thing I noticed was the fuel pump made a strange noise just before the car started. A sort of rapid tapping noise for about half a second. This has happened before and I thought it was the solenoid.

Any ideas?

[straggler]

Have discovered I have a sticky heater plug solenoid. If I give it a tap it will click into life. Will see if that is the issue by regular use of a screwdriver handle....

[dirtydirtydiesel]

HDi's don't really need the glow plugs to start, lot's out there have relay issues but run absolutely fine.

[straggler]

Mine's an XUDT

[GingerMagic]

My old 306 was an Xud and it always needed glow plugs - even in the middle of summer, even with a warm engine..!!
Never failed to start in 13 years though, and only replaced the glow plugs twice in that time...
Never had an issue like yours though, sorry...