850 T5 intermittent starting

[mike 850]

As in you dont hear the icv buzzing with the ignition on?

just double check this too:

http://www.davebarton.com/relay1323592diagram.jpg

[Sparkysparks]

No, this is the problem, sometimes it will connect the relay (ICV will buzz) and this will start. If I manually make this connection on the relay the ICV buzzes but it will not start still.

[mike 850]

ah ok, i think you can rule this relay out then? as if the icv is buzzing its getting its signal from the ecu and the relay is doing its job, can you have someone hold the icv while you crank on put a multimeter on it to see if the voltage dies when you crank?

[Sparkysparks]

Yes ive tried this relay and a spare on another 850 actually and they were fine. But my wiring is all back to being good now anyway.
I can check that next yes. What will that show though. Current draw from the starter? Its not firing the relay to begin with. Its got to be something controlling that relay

[mike 850]

exactly, thats the main injector relay so would definately cause a non start by testing if this is dropping during cranking will tell you the draw is too much so definately an earth/starter fault. if it doesn't drop the you need to go back to the cam and crank sensors and wiring.

Does it stink of fuel when it just cranks?

[mike 850]

https://www.volvoclub.org.uk/tech/se...sicTesting.pdf

A handy link for testing the other bits if needed

[Sparkysparks]

Sorry mike im getting confused. If the problem is before cranking it cant be the starter. Unless the starter is taking too much current on just ignition.
The relay only works properly when i manually shut the contact or earth the orange black wire. But even then the car wont start.
It doesnt stink of fuel no. No leaks, pressure is fine at 45psi at the rail.
The cam sensor was showing normal resistance and the crank sensor is new. We have issue with the crank sensor showing 0.7 volts on ignition though.

[mike 850]

here is what I think is happening, please correct me though as I have a habit of misreading sometimes

if you have pressure at the rail the main fuel pump relay is working enough to start.
the cam and crank sensors appear to be with their ranges.

when you turn the ignition on the ICV buzzes evertime?
If it does he relay and ecu signal to the fuel injection circuit is working, which should mean everything for the injectors to fire is in place?

so if its not firing the injectors i think its the draw from a bad earth/ starter when cranking is effecting this and maybe other signals stopping the injectors etc, hence no fuel smell.

Thanks what i am thinking..

[Sparkysparks]

Almost.
When I turn on ignition, fuel pump primes every time. But the ICV wont buzz, unless I physically take the lid off the main ignition relay and push the contacts together.
If I turn on ignition and fuel pump primes, and the ICV miraculously buzzes, it will start no problem. But that hasn't happened for a few weeks now.
This is why I'm leaning towards the ECU not doing its job properly now.

[mike 850]

Right so it's not the starter then, it must have something to do with that circuit ! I would check the voltage coming from the ecu to the relay, I can check mine to tell you what it should be with ignition on, if yours is the same and the icv is not buzzing there must be a fault after this relay, at least it should rule out ecu problems

[Sparkysparks]

That would be fantastic. Its got to be before the relay though. Either that or its not getting earth from elsewhere.

[mike 850]

Cool, I'll register what voltage the signal wire kicks out tomorrow evening. You could also check to see if you have 12v on the wire From pin 87? That would be the next check I think

[Blackdog]

Do the 850s have the same immobiliser system as the X70s?

If so it could be as simple as the antenna around the ignition barrel failing.

[Sparkysparks]

It could be. I have wiggled the key in the barrel to see if that helps.
I also visually checked the barrel connector and it all seemed fine.

[Blackdog]

Take the key out turn it over and then try. Repeat a few times if necessary. We had two ring antennas fail on our V70. The symptoms were simular to what you are describing.

[Sparkysparks]

I dont think the key is coded on mine.

[Sparkysparks]

Ill try to get a picture of it

[Sparkysparks]

http://www.michaelhyde.com/assets/im...RACK-KEY-2.jpg
Similar to that with volvo written on it.

[Blackdog]

Looks the same as our Ph1 V70s.

[Sparkysparks]

It would be lovely if thats the solution. Turn the key over. Somehow i dont think it will be though.