For all those who have starting problems with their 850, my story may be of interest:
My 1994 - 850 GLT ( 20Valve) had starting problems now and then. After cranking-up it ran for a split second but fel to zero r.p.m. This could happen anytime, with or without cold engine. The engine could be restarted by crancking-up for more than a minute (!) and keeping the throttle all the way down (and keeping it there). My Volvo dealer could not make any sence of it and I got used to it. Then one day I had starting problems again but was not able fix the problem as decribed above. The car was at my dealers garage for more than 3 days to find out what the problem was. It turned out to be that the starting engine was producing a current far higher than normal (because current increases as lifetime of the device increases they sad) . Now how can that be of any influence on strating the engine ? The cable from the starting engine runs (for several centimeters) in parallel to the cable of the very sensitive management port that looks at the movement sensor. Thereby it was blocking the information coming from the movement sensor thus no spark was produced. As soon as the cables were more than 15~20cm away from each other the engine ran fine after cranckin up. Of course this was not the permanent solution, although I think it is bad design to combine cables of different order. No Volvo design to me ! My dealer replaced the starting engine and I was offered a 50 % discount on labour finding the cause of this problem. (and I payed the bill of course). Grtz !Ron Bakker.