What would make a 1989 Volvo 760 turbo stalls whenever it stops?

Answer 1

I'm having a very similar problem with my 1988 Volvo 760 with the B230F/T engine.

We troubleshot the problem down to the ignition system.

We have tested the car as best we can with this intermittent problem and feel it is either the impulse sender in the distributor cap (Volvo repair shop says is most replaced part involved in this problem), the power stage or the ignition ECU.

If it would just fail consistently we could figure out which is the actual problem.

Now in case your problem is different than mine (It seems it is, somewhat, as mine stalled "SOMETIMES" when it stopped and also would have two other symptoms - it would have a momentary loss of power that would be revealed as a brief dip in RPM and a slight lurch or a more lingering similar loss that would see the RPM drop to zero and would be similar to downshifting in a manual to save your brakes, but it would recover.) you need to go back to basic troubleshooting:

Air

Fuel

Spark

Check your idle speed. Make sure your air filter is good and your air/fuel mixing is not having problems like with a stuck butterfly valve. See if you've got any loose vacuum lines. Could your fuel filter be clogging? Is your fuel pump weak? Dirty injectors? Have you done a tune up (plugs, wires and maybe distributor cap & rotor) lately? Check your timing.

I decided to do a tune-up starting with plugs and wires. When I went to take the #1 wire off it came apart in my hands! (I bought this car 2nd hand and haven't had it that long. The wires LOOKED good, but clearly they were not.)

Does it run rough in idle?

Anyway, that should get you started. If you have any manuals they have other suggestions (Chiltons, Haynes)

I had a similar problem with my 88 760 Turbo Wagon...it turned out to be the fuel pump which was beginning to fail and overheat at low flows which were caused by a failing pressure regulator (not bypassing enough fuel). This combination of failing parts worked well under load, but as soon as I got off the gas, it would stall - cool down - restart and run fine - so long as I was not idling.