Volvo: 1986 volvo wont start, air pressure regulator, fuel pump relay

Question
volvo starts when it wants to.Things I did.new fuel pumps and filters.new distr and rotor,new plug wires.cleaned throttle body and adjusted throttle switch,took an air pressure regulator off of an 86 that runs perfect,also I took off the the control module,computer,air mass meter assembly from good running car,fuel pump relay,and coil,and temperature sensor.There is fire at all plugs,and fuel comes out of fuel line at injector rail.The few times it did decide to start,I'd let it run until it reached operating temp,then I'd shut it off and restart it several times and it ran find,so I thought it was find.Then i'd let it sit for 30 min.and then it wouldn't start.It would just spin over.When it did start and checked the timing,it was perfect.I'm obsessed with this problem because I'm tryiong to sell it,I have two other volvos,86 and 87 240s.Please help,I thought I knew a lot about these cars but this problem has me very frustrated.Working one day and not the next.If I dont respond right away it's because I'm working offshore for 7 DAYS AT A time and I'm leaving on the 27th and will be back in 7 DAYS.                   Thanks,Lee Le Blanc

Answer
You mentioned just about everything I would have thought of to tackle this problem.  Here are a few other things you can check.  I know you confirmed fuel comes out at the rail, but also check the injectors and the rail itself for clogs.  Also, check your cold start valve.  You have the right idea, but in practice, when the engine turns over and over without catching, there are only 3 possibilities, A)there is no spark B)there is no fuel C)the timing is out so bad the spark and fuel aren't arriving at the right times.  Considering you checked A and B, I might also suggest you check the frequency valve, which controls the timing and should produce an audible buzz when the car is running.  A partial electrical short to this could cause start failures.  Speaking of shorts, your car falls into the year range of engine wire harness rot; have you replaced your harness or noticed flaking insulation?  These harness' literally dissolve over the years, causing numerous electrical issues that are almost impossible to track down.  I would scour your harness looking for breaks or bare wire.  Finally, if none of my tips worked, I recommend you go to www.brickboard.com and post a free question in the 240 forum.  You should get great answers from numerous fellow owners that will know more than me, esepcially about your particular year.  Good luck!