Volvo 850 not starting

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Sun 21 Dec 2003 18:52
Volvo 850 not starting - Ivor E Tower
Help: We have a 1995 850 2.5 10-valve that occasionally won't start - engine turns over OK, just will not fire up. Usually but not always this happens after a journey of 5 to 10 miles, then car is left for up to 1 hour. Strange thing is that if, after trying to start, the car is then left for a further half hour, it usually starts first time. No faults logged by ECU. Someone who has experienced this type of problem has suggested the "ignition amplifier".
Anyone else able to confirm or rule this out, or have any other ideas?
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Sun 21 Dec 2003 19:02
Volvo 850 not starting - Aprilia
Ign. amplifier is well known problem on this car. It is mounted on the inner wing IITC. Take it off and clean up connections thoroughly and then put a little copper grease on earthing contact to chassis. Then try it again.
If you're not getting any sparks after doing this then the amp needs to be replaced (£££)

IIRC there is also a big multiway conenctor in the engine compartment up against the firewall. This can suffer water ingress - so worth checking there.
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Mon 22 Dec 2003 08:44
Volvo 850 not starting - Cliff Pope
Be very careful with the amplifier. Certainly clean off any corrosion, but be cautious about screwing it back onto its heat sink - they are very sensitive to distortion from overtightened bolts.
If it is like the one on the 240/740 then there is no electrical connection to earth, but you should use a special heat-conducting grease between the module itself and the heat sink. Vaseline seems OK. Check its connector too.
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Mon 22 Dec 2003 10:00
Volvo 850 not starting - Aprilia
I'm working from memory, but I think on the 850 unit there *is* a earthing connection (one of the bolts). Endorse the comment about using thermal grease (get it from Maplins, if you don't already have some).
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Mon 22 Dec 2003 10:13
Volvo 850 not starting - Peter D
Vaselene is not suitable and is not termally conductive The is a proper conpoud for this but usually you do not need it as long as you do not clean it off. I would venture that the fault it is the fly wheel pick up that is at fault. Its output is a little low ( Common Fault ) at cranking a warmish engine it just is not producing enough output. This fault does not trigger an ECU fault but I think no output from the amp does. That is if you can mead the ECU Fault Mapping. Regards Peter
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Mon 22 Dec 2003 10:17
Volvo 850 not starting - Aprilia
Yes, it could be crank pickup. In fact it could be a few other things as well.
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