My1990 740gl will start fine, and run well for about a half hour at idol, and a few miles , and stalls. Starts right up and runs well. Cleaned the aic, sensor in the air filter box, all connections, swapped radio suppression relay with fan relay, both seemed to work. Checked intake for leaks, and was fine. Aux fan wouldn't come on when I engaged a/c. Temp gage was reading just above half. Wat is next. Trying to sell it, and need it 100%.

 

a faulty fuel pump/ fuel pump relay will show similar symptoms - as the relay passes more current it warms up and opens up shutting off fuel. This can be caused by a fuel pump on its way out - drawing more current than the aged relay can handle. Start by replacing or jumpering the relay to see if that helps. if it does, expect to replace the pump as well.

 

Crankshaft Position Sensor would be my first choice... Fuel relay, distant second, pump, doubtful.

 

Thanks lev. I should have mentioned what I replaced thus far .Crank sensor, TPS, rotor, distributor, plugs, and fuel filter. Checked intake for leaks at temp.

 

did you use quality parts for all those things ? volvo OEM or parts made by the volvo OE ?

the TPS is just a microswitch, I've never seen one go bad, and it could have been easily tested with a multimeter in ohms mode. 0 ohms at idle, open circuit as soon as you manually move the throttle a hair off idle.