740 Sedan stalls while driving Topic is solved

[Foot15]

1990 740, w/FI and auto, (UK model), stalls while driving. No pattern to when it happens. Can take from 1 to 15 minutes to get restarted. All lights, radio, accessories, etc. still work after stalling.

[760ti]

Couple things to check. Next time it stalls and doesn't restart, watch the tach. If it suddenly drops to 0, or doesn't budge when you try to restart, suspect the ignition. Either the Hall effect sensor or ignition power stage module. If the tach doesn't drop off suddenly, check the FI relay. The tach will at least bump up and off the stop if you try and restart if it's the FI relay.

[Terry]

My '92 740 does the exact same thing. And I have spent $2500 and stumped 3 volvo mechanics to no avail. It first starting shutting off at the end of my back up out of the driveway. Recently, for no reason, (after replacing all gas tank items and fuel pump, plus tune up), accelerating up a slight hill. I can feel power failing under my foot then all lights come on. It immediately restarts and drives fine. But what a white knuckler in heavy traffic. One mechanic blamed use of too high octane fuel, so I have switched to low octane, but still get the 'check engine' light when I reverse out of driveway which usually prefigures another shut down. I have printed out the response about the ignition, but if anyone else has any possible solution I will welcome them!

[760ti]

Your 92 has an OBD1 port (under the hood, driver's side strut tower). If you take the cap off module "a" that and put the plug on the outside of that little box into either port 2 or 6, and press the little button for 2 seconds, it will flash engine trouble codes. (little LED will flash) a code of 131 means there is a wiring fault or the rpm sensor is bad. I'm not sure if the '90 model year (or the UK versions) have the same OBD or computer setup.