I have just purchased a 1990 Volvo 740. On a number of occasions the engine has suddenly shut down - sometimes when driving at speed and other times when stationary. At other times it runs for hours with no problem whatsoever. There is no jerkiness or other warning signs prior to shutdown. In addition what may be related is that the brake light sometimes only intermittently works (and so far the engine shut down problem has only occurred while this brake light is not working well - though this may be a coincidence since it is something I have only recently started monitoring) Anyone have any ideas?

I drive an '88 740 wagon, no turbo. I have had two different problems that caused the motor to shut down. First is the infamous fuel pump relay. If its old replace it. Second is a soft spongy intake air hose (between the air filter box and the throttle body). My would hose collapsed when the vacuum reached some level, usually around 3000 RPM, especially when the thing was hot. Drove me nuts for a year. Cutting out without any warning at 3000 rpm then restarting like nothing happened only to do it again. Needless to say, I learned to pull out cautiously! The fix I used was to insert a 2-7/8 hose from the parts store inside the thing. The replacement part is $45, the hose was $8, besides the cheap hose was steel reinforced.... Worth a try.

Does the tachometer keep indicating engine speed while it is still turning over? If it does not work, that would indicate a problem in the ignition system.

Hi Richard,

Sounds like maybe the fuel pump relay? I'm not quite sure, but I know it has happened to others. Check the 700/900 FAQ section.