Volvo: intermitant starting problems, fuel pumps, hall effect switch

Question
My wife has a 1984 Volvo 240dl.  It has began having a problem  starting and has quit on her a few times.  It has been to the shop a few times with no luck.  We replaced the spark plug leads as they were corroded.  Though it seems it has not done the trick.  Usually it turns over with out catching, though this morning she tells me only the breaklight bulb indicator light came on, and it didn't turn over at all.  Not sure if it is related but we were having problems with the break lights last summer and we took it to an electrical shop.  He bypassed a control box of some type.   The breaklights worked again but the indicator light would remain on.  

Thanks for your time
M

Answer
M,
Check when you crank it to see if the fuel pumps are coming on. Do you have spark when this happens? The dist has a "Hall Effect" switch in it that goes bad. No spark would likely be the fault.  Also the connection at the ignition control unit becomes loose. There are sleeves that can be added to make a tight connection. Is it possible that the engine is so worn the compression it too low to fire? Is the fuel pressure too low/high? Fuel filter clogged?