Technical multijet sometimes not starting. Low voltage at solenoid trigger.

[Paul Jaggard]

After 190k miles in 17 years, finally a serious problem.
A few weeks ago, catastrophic clutch failure...required a new gearbox too.
A severe thumping, using a solid towing-bar, resulting in the towing hook tearing off the metal mounting, and plastic bumper.
Usual garage too busy, so neighbour replaced clutch and box.
Everything seemed ok, (although there was a very small thumping sound just as the engine caught)
OK for a time, then after a long hot journey, wouldn't start.
The fault has recurred sometimes since. After waiting a few hours it starts again.

I've since added a secondary earth from battery to engine, and thought that this had solved my problem

Now, usually it starts fine, but sometimes it acts as if there is only a low voltage getting to the solenoid trigger.
I've noticed that the tank fuel pump doesn't turn off after a few seconds like it should.

I've had 1 blown 20a ignition switch, fuse a week or two ago. (maybe I left the ignition switch on too long when the engine wouldn't start?)
Today, I've discovered that if I put on the interior light, then turn the ignition switch to its second position, if it dims slightly then the engine will start.
However if it dims a lot (to around 6v) and the solenoid sounds feeble, then it won't start.
I've had the starter off, and it always works fine on the bench (though I have to push the interior solenoid button with something harder than my finger to give continuity at the main contacts.
My Haynes circuit diagram takes 2 wires from the second position of the switch. One via engine compartment fusebox, and "short circuit coupling" (whatever that is), to the ECU.
And the other via passenger fusebox to Body Control Unit.
The interior light seems to get its power from the body control unit.

Why would my ignition switch give this low voltage, and will I have to dismantle the steering wheel to get at it?
Or is the problem elsewhere? ECU? BCU? Relay?
I noticed that my neighbour was much rougher manhandling the ECU cables than I would dare be, but unplugging, and reinserting them didn't help.

After 17 years virtually trouble free, it has come as a bit of a shock to have these problems all at once!

Has anyone else experienced anything similar, or have any suggestions?

 

[koalar]

How many volts while cranking

The fuse that blows which one, important they rarely go unless there is a fault.

Do you have a volt / multi-meter

Do you have a scan tool

It's will probably just be down to checking, battery, power and feeds

are we talking about not cranking? Or not starting

The bang on startup needs sorting also, I suspect the rear engine mount considering the dog bone was off for the gearbox replacement, although it needs proper diagnostic

 

[Paul Jaggard]

First of all thank you so much for bothering to reply, and so unexpectedly promptly.
As you've probably gathered, I'm no mechanic, but do like to know what's going on

Scan tool (cheap) says egr (but it has done for years)
Fuse has only blown once. f23 ignition switch. I've swapped it for the cigar lighter one. All my spare fuses are the old fashioned larger sized ones!
Haven't tested volts when cranking.
My multimeter is complete rubbish on dc volts I'm afraid.
But after the battery has charged overnight, I'll use the clarke meter, and see what cranking volts is.


Why would the fuel pump keep going?

I'm beginning to suspect the battery.
While in France, a battery company tested it at 420cca new should be 470, said it should be fine. This was at a time when it wouldn't crank. Then a few minutes later it started ok.
I have an old fashioned clarke tester, and a few days ago it tested around 450cca

Yesterday, having dismantled, and cleaned the starter, and put the extra earth strap on, I thought we had it sorted, but drove 10 miles, then stopped for 1 hour, and it only just started again.
However today, I fully charged it, and started the car a number of times over several hours with no problem. (only 2 or 3 seconds cranking)
Then suddenly, it quickly lost all cranking power, and tested dead.
Rather naughtily, I've just put it on a 5minute fast charge, and the car starts again. But just the once.
Its a Bosch battery, still under guarantee.

We have a petrol panda, with a nearly new bosch battery, 400cca, I think. Would it be a good idea to swap them over and see what happens?

 

[koalar]

.
Its a Bosch battery, still under guarantee.

We have a petrol panda, with a nearly new bosch battery, 400cca, I think. Would it be a good idea to swap them over and see what happens?

Yes

Subscription is by far the most relieble way

400cca is enough for the 1.3D


We also need to be sure it's charging properly

Need to do some investigation on the fuse back shortly

 

[Paul Jaggard]

Forgot to say, if it cranks at a reasonable speed it starts quickly.
BUT The first time it let us down, in France, on a hot day, after 100+ miles, towing 250kg, at mostly 50mph. We stopped for maybe 20 minutes, and then it cranked effectively, but would not start. tried several times, but not enough to run the battery down. 2 or 3 hours later it started ok.

 

[Paul Jaggard]

With regard to charging. I put my multimeter across the battery, and when the engine was running, the voltage rose by over a volt. I really must invest in a better digital meter!

 

[koalar]

With regard to charging. I put my multimeter across the battery, and when the engine was running, the voltage rose by over a volt. I really must invest in a better digital meter!

Should be 14.1V give or take a bit

And around 14.0V with the Blowers on full and headlights on

Cheap m/m normaly pretty accurate at the level of voltage

 

[Paul Jaggard]

Would that be at normal tickover, or with a little more welly?
I have a good quality analogue, but it is either 10v or 50v full scale, so not very easy, or accurate at the 0.1v level.
however, when I can start it again, I'll give that a try.

 

[koalar]

Would that be at normal tickover, or with a little more welly?
I have a good quality analogue, but it is either 10v or 50v full scale, so not very easy, or accurate at the 0.1v level.
however, when I can start it again, I'll give that a try.

Idle

 

[koalar]

How to Perform a Voltage Drop Test

Insufficient pressure and flow are an indication that a fuel pump is under-performing, but do not necessarily mean that it is failing.

www.delphiautoparts.com

The dimming more than normal internal lamp is pointing to a battery failing, however it's worth checking everything else

I am slightly concerned about F23 it's too much of a coincidence after the starter has just been out

A visual check of the smaller lead going to the starter is highly recomended, trapped or damaged

 

[Paul Jaggard]

OK have a decent meter, I think.

Battery charged overnight, tested at over 500cca on clarke tester , steady for 10secs.
recharged until charger said full.
Battery voltage now 12.78v
turn key to second position, and battery volts (at the battery terminals), drops to 11.55v
fuel pump keeps going.
turn key to start position, car starts almost immediately, the lowest voltage that I see is 9.9v

with no electric load, with engine at tickover, 14.2v
with full beam, and blower 14.09v

 

[Paul Jaggard]

I took the fuel pump fuse out, and the voltage, when ignition turned to that second position changed from 11.55 to 11.6.
So presumably it is not the pump causing such a big voltage drop.

Regarding the blown fuse f23. I spent so much time trying to remove the starter, removing the solenoid in-situ, connecting, and reconnecting the leads, leaving them dangling....It is very possible that at some point the feed cable was touching earth, when the key was turned. The fuse has only blown the once.

Although I tried to take a photo of the solenoid connections, I was never certain that I put the leads, and nuts on in the same order that they came off.
though with my socket depths, I think there was only one possible way. And anyway, the symptoms have not changed since the removal, and replacement.
When I get a chance, I'll run the car back up the ramps, and have a look to see if there is any damage to that wire.

 

[koalar]

OK have a decent meter, I think.

Battery charged overnight, tested at over 500cca on clarke tester , steady for 10secs.
recharged until charger said full.
Battery voltage now 12.78v
turn key to second position, and battery volts (at the battery terminals), drops to 11.55v
fuel pump keeps going.

This does not sound correct

I don't have the deisel, I have a poorly battery and needs recharging

It starts at 12.2V and at ignition on it drops to 11.8V

The pump should come on for a few seconds then the ECU should detect the engine has not been started and switch it off again

turn key to start position, car starts almost immediately, the lowest voltage that I see is 9.9v

Its hard to measure on a multimeter as it drops within a third of second

Here is an example of a petrol car that only just started, it fell from 12.6V to 7V in roughly the same time as a blink of an eye

On a multi meter you would have to disconnect the injectors and crank it for a few second to give the meter time to staberlise the reading

with no electric load, with engine at tickover, 14.2v
with full beam, and blower 14.09v

That's great the body computer is controlling the alternator output perfectly

All that's left is to check it's belt and we can cross the altetnator off the list

Swap the battery and see how much the other drops at ignition on

 

[AndyRKett]

While the engine earth might be good its probably worth making sure your neighbor has tightened up all the connections on the starter motor properly as a loose connection there can also cause similar problems to having a bad earth.

I know it sounds like there are other potential issues going on but that is something to check. I seem to recall on the multijet the starter attaches to the gearbox bell housing or there is some cross over with the starter and bell housing I must admit its been about 9 years since I worked on one.

 

[koalar]

While the engine earth might be good its probably worth making sure your neighbor has tightened up all the connections on the starter motor properly as a loose connection there can also cause similar problems to having a bad earth.

Interior light goes dim, when it failing

Unlikely to be a loose starter wire

I know it sounds like there are other potential issues going on but that is something to check. I seem to recall on the multijet the starter attaches to the gearbox bell housing or there is some cross over with the starter and bell housing I must admit its been about 9 years since I worked on one.

It should just unbolt and move out of the way, no need to undo the connector

No way of knowing what was done

I am worried that F23 blew, too much current is usually a faulty part or a short in the wiring

The excessive drop in voltage at the battery terminals at ignition on is still pointing to a short or faulty battery (most likely)

 

[DaveMcT]

The symptoms look like battery. However, starter power and trigger connection are "unusual" (at least in my opinion). A complex plastic block aligns a large diameter lug on the trigger wire against the motor end of that block. The two heavy lugs are aligned by the rest of the black. You have to get two lumps of plastic and three electrical items all lined up before the M8 retaining nut is tightened. Its a real pain in the arse but definitely makes a difference to starting performance when it's not right.

 

[AndyRKett]

The symptoms look like battery. However, starter power and trigger connection are "unusual" (at least in my opinion). A complex plastic block aligns a large diameter lug on the trigger wire against the motor end of that block. The two heavy lugs are aligned by the rest of the black. You have to get two lumps of plastic and three electrical items all lined up before the M8 retaining nut is tightened. Its a real pain in the arse but definitely makes a difference to starting performance when it's not right.

I remember it being a real pain to sort out.

 

[AndyRKett]

Interior light goes dim, when it failing

Unlikely to be a loose starter wire

If there is a high resistance because of a poor connection to the starter it pushed up the current demand and you will get diming or a voltage drop in other areas.

It is simple to check to make sure connections to the starter are good and it should not be ruled out.

It should just unbolt and move out of the way, no need to undo the connector

I seem to remember is is not as straight forward on the Multijet and removal of the gearbox basically requires removal of the starter. there isn't room to hang it out the way,

I am worried that F23 blew, too much current is usually a faulty part or a short in the wiring

The excessive drop in voltage at the battery terminals at ignition on is still pointing to a short or faulty battery (most likely)

A big voltage drop on the battery could still be an issue with the starter so that should be checked and is relatively easy to do.
If a fuse blows once and not again then it can just be a one off, old fuse or some odd one off spike, but if its replaced and doesn't blow again then I would normally move on and ignore it. If it had blown multiple times either straight away or after a short period of time it might warrant further investigation.

 

[koalar]

If there is a high resistance because of a poor connection to the starter it pushed up the current demand and you will get diming or a voltage drop in other areas.

Are you sure?

Poor connection on the starter equals higher resistance, higher resitance equals less current. Less draw from the starter means there's more capacity for the rest of the system, Bulb should be brighter as it fails if the earth or power feed to the starter were the fault.

That's how I see it

 

[koalar]

I took the fuel pump fuse out, and the voltage, when ignition turned to that second position changed from 11.55 to 11.6.
So presumably it is not the pump causing such a big voltage drop.

Sound like a weak battery, try your other

Regarding the blown fuse f23. I spent so much time trying to remove the starter, removing the solenoid in-situ, connecting, and reconnecting the leads, leaving them dangling....It is very possible that at some point the feed cable was touching earth, when the key was turned. The fuse has only blown the once.

Makes sense, dangle live wires is never good idea. And potentially expensive, fingers cross just a fuse it was the last time someone forgot to refit the small cable and left it touching the engine block, so the odds are good

Although I tried to take a photo of the solenoid connections, I was never certain that I put the leads, and nuts on in the same order that they came off.

There only two wires as its spinning I would assume they are okay

though with my socket depths, I think there was only one possible way. And anyway, the symptoms have not changed since the removal, and replacement.
When I get a chance, I'll run the car back up the ramps, and have a look to see if there is any damage to that wire.

Great