Club 80-90 Forums

Finally got the camper on four wheels after a full engine rebuild. Got the engine running before installation to see if there were any issues and it fired up great.

http://youtu.be/HCIXXKuCSYk

I have tried to fire her up today and she turns over fine. I know compression is good and fuel is fine. After a while trying to trace the issue I used some 'HT lights' on the spark plugs to see if the ignition was working properly and found that the spark plugs were firing for the first few turns of the engine and then stopping whilst it's turning over. If I try again straight away I get no spark at all. I have a standard ignition set up and have tried with & without the idle stabilizing unit but no difference.

If I pump a little extra fuel into the carb, it will fire briefly before the sparks stop. I've had a look in the Wiki but can't find anything relating to a problem like this. I'm pretty sure I have the electrics connected correctly. The Green coil wire on connector 1 and the black wires on 15. I am also powering my electric choke and fuel pump off of the black wire connection, but trying with these disconnected also made no difference. Is there something obvious I could be missing as I'm suspecting it's something to do with the electronic ignition maybe

Can't remember for sure but there should be some kind of ballast resistor in the circuit to boost voltage when starting. When a ballast resistor goes the engine will run whilst key is in start position but as soon as key is released from start pos. to normal running it will cut out. It may be this or I could be totally wrong (again) google ballast resistor and see what you can find.

blacky wrote:Can't remember for sure but there should be some kind of ballast resistor in the circuit to boost voltage when starting. When a ballast resistor goes the engine will run whilst key is in start position but as soon as key is released from start pos. to normal running it will cut out. It may be this or I could be totally wrong (again) google ballast resistor and see what you can find.

^^ This happened on my MkI Scirocco, with the same symptoms.

Ian

I know what you're saying. Although I had a second go at my issue this afternoon which discounts that issue. I used a connection from the alternator (Which runs directly from the battery) to power the ignition components directly with +12V. This lead to the same issue, so discounts the electrics on the camper. I must be an ignition component issue.

I substituted in a different coil - no change
I had previously applied heatsink paste between the black electronic unit and heatsink. I cleaned it off thinking it could have been an earthing issue - no change
I have shorted out the idle stabilisation unit - no change

I'm suspecting the black box may be the issue as there's not a lot else left it could be? Has anyone had anything like this in the past?

Haha! Sussed it.

Embarrasingly I had connected the ignition unit's earth wire to the oil pressure sensor, not to the earth blade terminal hidden away under the dizzy. This would explain why I only got an initial spark as once oil pressure was achieved the earth for the ignition would be disconnected!

D 'OH

She's running sweetly now for the first time since I bought her last Feb!

Well done. And also for admitting to the advanced muppetry too

Ian

Cunning - an oil pressure operated ignition immobiliser.

Footprint wrote:Cunning - an oil pressure operated ignition immobiliser.

People have accidentally created a similar carb heater version on the 1.9 WBXer engines by crossing the wires to the fuel cut-off solenoid

Ian

Footprint wrote:Cunning - an oil pressure operated ignition immobiliser.

Then there is the opposite way round, as used on some big Diesels (caterpillar etc), where the engine cannot fire up until oil pressure is present. A good idea I always thought.


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ghost123uk wrote:

Footprint wrote:Cunning - an oil pressure operated ignition immobiliser.

Then there is the opposite way round, as used on some big Diesels (caterpillar etc), where the engine cannot fire up until oil pressure is present. A good idea I always thought.


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I could be wrong but I've a feeling that my MkI Scirocco and a mate's Audi GT Coupe 5 pot 2.0 used to crank without firing till a certain pressure was reached. (?)