Volvo Repair: Occasionally not able to start my 1991 Volvo 740, volvo 740, mechanical shop

Question
Hi Roger
I have a 1991 740 GL sedan and have lately had occasional problems with starting. The first time it did this I could not start it and a local mechanical shop where they replaced the coil, and it worked fine for a few months. Now it is doing it again. Approximately once a week it has trouble starting. I had it towed back to the shop and, sure enough, they found it started every time for them (cold or hot) and suggested it might be a sensor or something. The engine is getting lots of cranking power (I even tried battery boosting) and there is lots of clean gas (new filter). Lately when I first turn the key and it sounds like it might not start, I then put the gas pedal to the floor and hold it there and it starts up. The problem usually occurs after it has been sitting for a while or overnight, and once it has been running without being turned off for more than 3 or 4 hours there is seldom a problem. Any ideas? Thanks, Murray

Answer
Murray, depends on what fuel system you have.  If its the regina/rex system, then there may be an issue with the fuel pump.  If its a bosch system, there may be a faulty impulse sensor or ignition power stage issue.  Its frustrating for me as a tech to have a car not duplicate the problem.  I dont just swap parts and send the customer on their way.  On this issue, I would have to have the car do the problem, then perform tests to see whats going on.  I hope this helped.  Roger