Rover V8 - starting issue

[Ranger 6]

Scenario:

Drove the car in and stopped - switched off and walked away - it was running completely normally

Came back to the car a few days later - won't start - turns over freely

The car is a factory built one - not a conversion, and all parts are standard

Symptoms:
There is only one spark (tested with a plug) at the start of turning the key and another spark when turning the key off
Otherwise the engine will not run

Tested/changed:
New Ignition module (tested and changed) - it's a two pin module fixed to the side of the distributor
Distributor - std fit electronic ignition - hall effect sensor checked
HT leads - resistance check
Ignition switch bypassed to coil
New coil
Earth checked (bypassed with HT lead)

Stumped a couple of experienced mechanics who have had a look

Next thing to change is the HT leads and try that - we have swapped them to see if the king lead has died, but no difference

So, what could be the 'fix' here?

[richhead]

Does it have a ballast resistor?
If voltages at the coil are ok, either 6v or 12v depending on the set up.
If ok i would be looking at the ignition barrel.

[Ranger 6]

When you say ballast resistor - is that also known as a condenser?

Doesn't have one as it's electronic ignition.

Bypassed the ignition with a cable direct to the coil.

[richhead]

Ranger 6 said:

When you say ballast resistor - is that also known as a condenser?

Doesn't have one as it's electronic ignition.

Bypassed the ignition with a cable direct to the coil.

No its normaly in the supply feed to the coil, often close to the coil.
It may not have one.
be worth measuring the voltage at the coil, and also if its switching the coil earth as it turns over.
What car is it?

[Ranger 6]

OK - thanks - checked on the ballast resistor and it doesn't have one

He did a load of check on the coil - I'll have to check if he did the switching.

Land Rover 90

[littleredrooster]

My money's on the Hall Effect sensor. The fact that it sparks when the circuit is energized/de-energized probably suggest that the Module and coil are both working.

I had one fail on a BMW bike some years back - it started being a bit awkward when hot, then stopped working altogether. I initially blamed coils, but it was the sensor.

[richhead]

littleredrooster said:

My money's on the Hall Effect sensor. The fact that it sparks when the circuit is energized/de-energized probably suggest that the Module and coil are both working.

I had one fail on a BMW bike some years back - it started being a bit awkward when hot, then stopped working altogether. I initially blamed coils, but it was the sensor.

I would agree, but the op does say this has been checked, Best way to check is as i said, an easy way can be a old fashioned test light across the coil termilals and see if it flashes on cranking, that rules out everything apart from coil/leads/plugs.
Also op you say you changed the coil, is it the same one, there are 12v coils and 6v coils, often not obvious which is which. But if there is no ballast then most likely a 12v one.
If its a 2 wire module and a hall sensor, there isnt really alot to go wrong tbh and easy to test.

[stevieturbo]

Ranger 6 said:

Scenario:

Drove the car in and stopped - switched off and walked away - it was running completely normally

Came back to the car a few days later - won't start - turns over freely

The car is a factory built one - not a conversion, and all parts are standard

Symptoms:
There is only one spark (tested with a plug) at the start of turning the key and another spark when turning the key off
Otherwise the engine will not run

Tested/changed:
New Ignition module (tested and changed) - it's a two pin module fixed to the side of the distributor
Distributor - std fit electronic ignition - hall effect sensor checked
HT leads - resistance check
Ignition switch bypassed to coil
New coil
Earth checked (bypassed with HT lead)

Stumped a couple of experienced mechanics who have had a look

Next thing to change is the HT leads and try that - we have swapped them to see if the king lead has died, but no difference

So, what could be the 'fix' here?

Perhaps give us a clue as to what car ? what age ? And these checks....exactly what and how are you "checking" ?

You're only talking about a distributor, so is it a carburettor car ? fuel injection ? other ?

[Ranger 6]

richhead said:

littleredrooster said:

My money's on the Hall Effect sensor. The fact that it sparks when the circuit is energized/de-energized probably suggest that the Module and coil are both working.

I had one fail on a BMW bike some years back - it started being a bit awkward when hot, then stopped working altogether. I initially blamed coils, but it was the sensor.

I would agree, but the op does say this has been checked, Best way to check is as i said, an easy way can be a old fashioned test light across the coil termilals and see if it flashes on cranking, that rules out everything apart from coil/leads/plugs.
Also op you say you changed the coil, is it the same one, there are 12v coils and 6v coils, often not obvious which is which. But if there is no ballast then most likely a 12v one.
If its a 2 wire module and a hall sensor, there isnt really alot to go wrong tbh and easy to test.

How do you check a hall effect sensor – we took the dizzy apart enough to check the magnet on the sensor. I think it’s pulsing enough to trigger a spark.

Short of a new distributor – what would you buy to fix it?

Coil – yes – swapped with a new one – the same as was fitted – 12v

Yes the ignition amplifier is a two pin one that’s fitted on the side of the dizzy – new Intermoto one and pulses when checked

stevieturbo said:

Perhaps give us a clue as to what car ? what age ? And these checks....exactly what and how are you "checking" ?

You're only talking about a distributor, so is it a carburettor car ? fuel injection ? other ?

Car – as mentioned above, it’s a Land Rover 90
1988 CSW – 3.5 on SU carbs

Checks done using a multimeter and ‘module checking box’ – pulled out of the back of a cupboard as no one uses stuff this old any more

[richhead]

Ranger 6 said:

richhead said:

littleredrooster said:

My money's on the Hall Effect sensor. The fact that it sparks when the circuit is energized/de-energized probably suggest that the Module and coil are both working.

I had one fail on a BMW bike some years back - it started being a bit awkward when hot, then stopped working altogether. I initially blamed coils, but it was the sensor.

I would agree, but the op does say this has been checked, Best way to check is as i said, an easy way can be a old fashioned test light across the coil termilals and see if it flashes on cranking, that rules out everything apart from coil/leads/plugs.
Also op you say you changed the coil, is it the same one, there are 12v coils and 6v coils, often not obvious which is which. But if there is no ballast then most likely a 12v one.
If its a 2 wire module and a hall sensor, there isnt really alot to go wrong tbh and easy to test.

How do you check a hall effect sensor – we took the dizzy apart enough to check the magnet on the sensor. I think it’s pulsing enough to trigger a spark.

Short of a new distributor – what would you buy to fix it?

Coil – yes – swapped with a new one – the same as was fitted – 12v

Yes the ignition amplifier is a two pin one that’s fitted on the side of the dizzy – new Intermoto one and pulses when checked

stevieturbo said:

Perhaps give us a clue as to what car ? what age ? And these checks....exactly what and how are you "checking" ?

You're only talking about a distributor, so is it a carburettor car ? fuel injection ? other ?

Car – as mentioned above, it’s a Land Rover 90
1988 CSW – 3.5 on SU carbs

Checks done using a multimeter and ‘module checking box’ – pulled out of the back of a cupboard as no one uses stuff this old any more

Those old module checking things we never much good, takes me back, nothing a good multimeter will tell you really.
That said, if the module is sending a pulse, then that kind of says the distributer is doing its job, but is it switching the coil? Could even be a wiring fault between the two.
Like i said before, is the coil being switched? Very easy to check.

[Ranger 6]

Yes, the old module took him back too - I had to find a new battery to get the thing working properly.

Some of the wiring between the ignition amplifier and coil has been replaced as it was looking bad. the rest is ok and has been checked with a meter.

The coil is being switched

The shopping list is currently a new King lead and a new sensor for the dizzy

[richhead]

if the coil is being switched then try testing for a spark at the distributor end of the king lead, if there is one, all good, if not its either the coil or the king lead , it cant be anything else. If there is a spark at the end of the lead, then its either the rotor arm or cap, or all the plug leads(unlikely)
tbh this is all fairly simple diagnosis

[Ranger 6]

Yes - we've done all that and are only getting the one spark at the turn of the key

[richhead]

Ranger 6 said:

Yes - we've done all that and are only getting the one spark at the turn of the key

Done what?

[Getragdogleg]

Does it have an oil pressure sender unit that tells the ignition side of things all is well ?

I have had similar faults on other cars that turned out to be this system being broken, the pressure gauge still worked but the other circuit in the sender was goosed.

[richhead]

Getragdogleg said:

Does it have an oil pressure sender unit that tells the ignition side of things all is well ?

I have had similar faults on other cars that turned out to be this system being broken, the pressure gauge still worked but the other circuit in the sender was goosed.

That , and all other safety systems would be rulled out it the coil is getting a voltage and the coil earth being switched, it sounds like the op has tested this

[Belle427]

Is the rotor arm actually spinning around properly?
Not uncommon for the drive gears to strip teeth.

[Ranger 6]

richhead said:

Ranger 6 said:

Yes - we've done all that and are only getting the one spark at the turn of the key

Done what?

This

richhead said:

try testing for a spark at the distributor end of the king lead,

Used the plug lead from No: 1 to check

Going to get a new king lead anyway as we've broken the connector pulling it and shoving it through all the testing.

richhead said:

If there is a spark at the end of the lead

Yes - again just the one spark at each turn of the key

richhead said:

Getragdogleg said:

Does it have an oil pressure sender unit that tells the ignition side of things all is well ?

I have had similar faults on other cars that turned out to be this system being broken, the pressure gauge still worked but the other circuit in the sender was goosed.

That , and all other safety systems would be rulled out it the coil is getting a voltage and the coil earth being switched, it sounds like the op has tested this

I've got a spare sender which we can try - but I doubt it. A 90 isn't that clever and it's run with the pressure warning light on in the past (cheap eBay senders!)

Belle427 said:

Is the rotor arm actually spinning around properly?
Not uncommon for the drive gears to strip teeth.

In a V8? They're all metal

But yes, everything is turning correctly and timed

[Ranger 6]

@richhead - where are you?

Fancy coming round and having a look

[littleredrooster]

Do you have a different rotor arm you could try? I have recollections of a batch of counterfeit (i.e. crap) Lucas rotor arms coming from China. Looked the part, but sent the spark straight to earth through a hairline crack.