Help needed,,, please !!!!

Hi all
Sorry for the intusion I know what its like to be part of a forum and have people coming on just to ask for free advise and then dissapear as I am a member of a trike forum and an area rep and we get it all the time.

BUT

I run a small garage in Anlaby near Hull and a customer and very good friend of mine has an alpine gta v6 turbo, I have had it in my workshop now for about 9 months, doing it up, painting it lowering it etc.
When I first worked on it a year ago the owner would go to it, sometimes it would start and some times not. He had been told by an AA guy that he ignition switch was a common problem on the renault 19s etc so we fitted him a new switch had it in the workshop and there it has been until last month when he got it back all painted and looking lovely.
But it still has the same fault, Ive onlyseen it not start twice and as soon as I start probing anywhere it goes again.
I have been able to work out whats stopping it from starting,,, No spark, but there is fuel.
The fuel pump and ignition curcuit are on the same ignition switch curcuit so it cant be the switch.
The only problem is that I can have the car for a week and start it a dozzen times a day without it missing a beat, as soon as I give it back to the owner it wont start again.
I am running out of options and things to check.
Have any of you out there had a similar fault or can anyone point me in the right direction as this car is driving me mad.
Any help would be much appriciated.

Thank you in advance
Dave

Check your earths or crank sensor

Check your earths or crank sensor

Yeh I thought possibly crank spped sensor , Earths.. I would have thought they would take the starter and fuel pump out first before the ignition wouldnt they ?.

Dave

You say you have fuel but no spark - the fuel pump priming is not the same as the injectors firing when you crank. Check with an LED across one of the injector plugs to see if it flashes while cranking. The rev counter will flicker during cranking if the spark signal is getting as far as the coil driver.

Does he keep it outside? You keep it inside? = HT stuff?

Hi stunned monkey

Yes he keeps it out side but so do I.
That is a very good point about the injectors, now the only prob is getting it to not start with me.
If the injectors dont fire what would you sugest, also if they do, what would you sugest??.

Cheetrs

Dave

Have you checked the dizzy cap and rotor yet?. They are prone for corrosion, and have to be regularly changed.

The way to check is pull the king lead off the coil pack and see if you get a spark direct from there on cranking. If you do and the car still doesnt run then its the dizzy etc..

If there is no spark at the coil, then its the coil itself, or the earth strap to it, or its not getting a signal from the TDC sensor, but the way you can check this is crank the car, put a screw driver to the body of a fuel injector and listen if its clicking to see if fuel is flowing (and thats only if your sure the pump is priming )

ECU uses the TDC sensor then drives Coil pack and injectors. If both injectors AND ignition fails then it may well be upstream of the ECU, ie TDC sensor, if the injectors are firing but no spark, then you know the TDC sensor is fine and it must be HT stuff - leads, plugs, cap, rotor etc

Have you got an hall effect timing light? Mine is a godsend to troubleshoot ignition stuff - pulling a lead off only tells you if there's a spark at one atmosphere, not under compression, a hall effect timing light will tell you that the spark plugs are actually sparking. So for eg if the rev counter moves (driver stage remember) but the timing light doesn't pick up a spark then it's defo HT stuff.

I think you need to give your customer some test to try hmself - eg does the rev counter rmove when cranking, can you do the injector test Dave suggests (if you don't know what you're listening for, probably bes tto use an LED under cranking conditions)

Lots of ideas, could write all night!

- pulling a lead off only tells you if there's a spark at one atmosphere, not under compression, a hall effect timing light will tell you that the spark plugs are actually sparking. !

Lol, or common sense. If you deffo have fuel, and spark at the lead, and it still doesnt run, then you can just deduce there is a problem at the plug end under compression.

ECU uses the TDC sensor then drives Coil pack and injectors. If both injectors AND ignition fails then it may well be upstream of the ECU, ie TDC sensor, if the injectors are firing but no spark, then you know the TDC sensor is fine and it must be HT stuff - leads, plugs, cap, rotor etc

!

As I mentioned above, don't forget the coil pack, or the power supply to the coil pack, or the amplifier on the coil, or the main earth to the turret, or even the 3 pin plug in the coilpack itself.

can you do the injector test Dave suggests (if you don't know what you're listening for, probably bes tto use an LED under cranking conditions)

But an LED doesn't prove the injectors are working though, just that power is getting to them. Stuck injectors won't click, though they will still be pulsed.

And if you have a voltage or earth problem to known working injectors, and LED will still light due to low current demands, though there might not be enough power to actually open the injectors.

Hi all

Thanks for all the advice but I think we are going a bit of track.
The injectors I would asume work fine with no faults because the car does run there fore all 6 injectors wont fail at once. I do need to check power supply to them when it wont go though.
HT leads are all fine although it could be the king lead again I have checked more than one lead, with a plug in it when it wont go.
Coil and tdc sensor where top of my list. Until I have just found out from my customer, when it wont go (always on the key) the car will push off straight away and start fine until the next time it decides not to go. Surlly that points to ignition switch again doesn't it????
MMMM, starting to lose the plat now. Where are the earthing points on these cars ??, I also need to check them I think.

Thanks for all your help so far, what do you think about the being able ro push the car off???

Dave

Hi all

Thanks for all the advice but I think we are going a bit of track.
The injectors I would asume work fine with no faults because the car does run there fore all 6 injectors wont fail at once. I do need to check power supply to them when it wont go though.
HT leads are all fine although it could be the king lead again I have checked more than one lead, with a plug in it when it wont go.
Coil and tdc sensor where top of my list. Until I have just found out from my customer, when it wont go (always on the key) the car will push off straight away and start fine until the next time it decides not to go. Surlly that points to ignition switch again doesn't it????
MMMM, starting to lose the plat now. Where are the earthing points on these cars ??, I also need to check them I think.

Thanks for all your help so far, what do you think about the being able ro push the car off???

Dave

But if the car turns over and doesnt run, then It can't be the ignition switch, or does it not turn over at all? If it doesnt turn over, then its nothing to do with the ECU/sensors etc..

All 6 injectors will stop together as they are batched all on one output. If the voltage is low, or badly earthed, they will still light an LED, but not open. One of the fuel rails should be eathed to the engine. Temporarily hook an earth from the engine to the suspension turret.

The earth for the coil pack is a fat strap type going to the drivers side turret.

There is also a main earth to check from the gearbox to the transmission tunnel.

I would really check the dizzy cap before doing anything, and its not a tricky job like the TDC sensor. The centre carbon pins are prone for breaking off...

Hi

Yes have had the cap of a couple of times and its like new.
Yes the car turns over but wont fire but theses ignition switches have a supply to the starter and a supply to the ignition curcuit dont they ??.
Do these cars have any relays to the engine ignition curcuits ???


cheers Dave

Two relays next to ecu .One is fuel pump other injectors ( big brown,big red wires ) This could be at fault see if it's getting really hot .give it a tap if it wont start and see .

Hi

Yes have had the cap of a couple of times and its like new.
Yes the car turns over but wont fire but theses ignition switches have a supply to the starter and a supply to the ignition curcuit dont they ??.
Do these cars have any relays to the engine ignition curcuits ???


cheers Dave

Yes, there are two relays next to the ECU inbetween the rear seats.

One for the fuel pump/injectors and for the ignition system.

The fuel pump should prime for 3 seconds on when turning the key (pre-starting) This is triggered by the ecu, so If this happens you know both the ecu and relay are getting power.

The other relay is just triggered by ignition. So you need to check both of these are working, try a known working relay, or just swap the two over.

If the car will always go on a push start, then this doesnt really point to the relays etc, moreso a TDC sensor issue. Ive had cars in the workshop with a slightly tired starter, and a bad TDC sensor that won't start, but will when bumpstarted, simply because the slower than usual cranking and weak signal isnt enough to start it.