Volvo Repair: 1987 Volvo 240, 2 different things, volvo 240

Question
Hi i am working on a 1987 volvo 240 with a 4cyl. ans it has a problem where if you drive it for about 20 minuits and turn it off then let it sid for a cuple minites it wont start agian... but its starts fine after a few hours. and some times it will die when your driving and wont start agian for quite some time.... i thought it was ignition but it still has spark when it dies and seems to have fuel pressure to the fuel rail. i am stumped. and i havent worked on volvo's much

Answer
seems to have and having fuel pressure can be 2 different things.if it has fuel to the fuel rail and has good pressure and spark.then there may be a problem in the control unit ground signal to the injectors.you would need to check for power to the injectors and for an oscillating ground signal when tryig to start the car.